# coding: utf-8
from enum import IntEnum
from collections import namedtuple
from struct import calcsize, unpack, pack
from typing import Union, Any
from collections.abc import Callable
from multiprocessing import Queue, Event
from multiprocessing.managers import Namespace
from time import time
from .._global import OptionalModule
try:
from usb import util
from usb.core import find, USBError
Ftdi_req_out = util.build_request_type(util.CTRL_OUT,
util.CTRL_TYPE_VENDOR,
util.CTRL_RECIPIENT_DEVICE)
Ftdi_req_in = util.build_request_type(util.CTRL_IN,
util.CTRL_TYPE_VENDOR,
util.CTRL_RECIPIENT_DEVICE)
except (ModuleNotFoundError, ImportError):
util = OptionalModule("pyusb")
find = OptionalModule("pyusb")
USBError = OptionalModule("pyusb")
Ftdi_req_out = 0x40
Ftdi_req_in = 0xC0
# Todo:
# Check Windows compatibility (is kernel driver active)
# Add fast FT232H mode ?
ft232h_cmds = {'write_bytes_PVE_MSB': 0x10,
'write_bytes_NVE_MSB': 0x11,
'write_bits_NVE_MSB': 0x13,
'write_bytes_PVE_LSB': 0x18,
'write_bytes_NVE_LSB': 0x19,
'read_bytes_PVE_MSB': 0x20,
'read_bits_PVE_MSB': 0x22,
'read_bytes_NVE_MSB': 0x24,
'read_bytes_PVE_LSB': 0x28,
'read_bytes_NVE_LSB': 0x2C,
'rw_bytes_PVE_NVE_MSB': 0x31,
'rw_bytes_NVE_PVE_MSB': 0x34,
'rw_bytes_PVE_NVE_LSB': 0x39,
'rw_bytes_NVE_PVE_LSB': 0x3C,
'set_bits_low': 0x80,
'get_bits_low': 0x81,
'set_bits_high': 0x82,
'get_bits_high': 0x83,
'loopback_start': 0x84,
'loopback_end': 0x85,
'set_tck_divisor': 0x86,
'send_immediate': 0x87,
'disable_clk_div5': 0x8A,
'enable_clk_div5': 0x8B,
'enable_clk_3phase': 0x8C,
'disable_clk_3phase': 0x8D,
'enable_clk_adaptative': 0x96,
'disable_clk_adaptative': 0x97,
'drive_zero': 0x9E}
ft232h_sio_req = {'reset': 0x00,
'set_event_char': 0x06,
'set_error_char': 0x07,
'set_latency_timer': 0x09,
'set_bitmode': 0x0B,
'read_eeprom': 0x90,
'write_eeprom': 0x91}
ft232h_sio_args = {'reset': 0,
'purge_RX': 1,
'purge_TX': 2}
Ftdi_vendor_id = 0x0403
ft232h_product_id = 0x6014
ft232h_latency = {'min': 1,
'max': 255}
ft232h_clock = {'base': 6.0E6,
'high': 30.0E6}
ft232h_tx_empty_bits = 0x60
ft232h_max_payload = 0xFF
ft232h_mpsse_bit_delay = 0.5E-6
ft232h_port_width = 16
ft232h_eeprom_size = 256
ft232h_eeprom = {'has_serial_pos': 0x0A,
'str_table': 0x0E,
'str_position': 0xA0}
ft232h_pins = {'SCL': 0x01,
'SDAO': 0x02,
'SDAI': 0x04,
'SCL_FB': 0x80,
'SCK': 0x01,
'DO': 0x02,
'DI': 0x04,
'CS': 0x08}
ft232h_i2c_timings = namedtuple('I2CTimings',
't_hd_sta t_su_sta t_su_sto t_buf')
ft232h_modes = ['SPI', 'I2C', 'GPIO_only', 'Write_serial_nr']
ft232h_pin_nr = {pin: index for pin, index in zip(
['D{}'.format(i) for i in range(8)] +
['C{}'.format(i) for i in range(8)], [2 ** j for j in range(16)])}
ft232h_i2c_speed = {100E3: ft232h_i2c_timings(4.0E-6, 4.7E-6, 4.0E-6, 4.7E-6),
400E3: ft232h_i2c_timings(0.6E-6, 0.6E-6, 0.6E-6, 1.3E-6),
1E6: ft232h_i2c_timings(0.26E-6, 0.26E-6, 0.26E-6, 0.5E-6)}
[docs]class Find_serial_number:
"""A class used for finding USB devices matching a given serial number, using
the usb.core.find method."""
def __init__(self, serial_number: str) -> None:
self.serial_number = serial_number
def __call__(self, device) -> bool:
return device.serial_number == self.serial_number
[docs]class ft232h:
"""A class for controlling FTDI's USB to Serial FT232H.
Communication in SPI and I2C are implemented, along with GPIO control. The
name of the methods for SPI and I2C communication are those of :mod:`smbus`
and :mod:`spidev` libraries, in order to facilitate the use and the
integration in a multi-backend environment. This class also allows to write a
USB serial number in the EEPROM, as there's no default serial number on the
chip.
Note:
The FT232H does not support clock stretching and this may cause bugs with
some I2C devices. Lowering the ``i2c_speed`` may solve the problem.
Important:
If using Adafruit's board, its `I2C Mode` switch should of course be set to
the correct value according to the chosen mode.
Important:
**Only for Linux users:** In order to drive the FT232H, the appropriate
udev rule should be set. This can be done using the `udev_rule_setter`
utility in ``crappy``'s `util` folder. It is also possible to add it
manually by running:
::
$ echo "SUBSYSTEM==\\"usb\\", ATTR{idVendor}==\\"0403\\", \
MODE=\\"0666\\\"" | sudo tee ftdi.rules > /dev/null 2>&1
in a shell opened in ``/etc/udev/rules.d``.
Important:
For controlling several FT232H from the same computer, it is first necessary
to set their USB serial numbers. Otherwise an error will be raised. This can
be done using the crappy utility ``Set_ft232h_serial_nr.py``.
"""
[docs] class BitMode(IntEnum):
"""Commands for changing the bit mode."""
RESET = 0x00 # switch off alternative mode (default to UART)
BITBANG = 0x01 # classical asynchronous bitbang mode
MPSSE = 0x02 # MPSSE mode, available on 2232x chips
SYNCBB = 0x04 # synchronous bitbang mode
MCU = 0x08 # MCU Host Bus Emulation mode,
OPTO = 0x10 # Fast Opto-Isolated Serial Interface Mode
CBUS = 0x20 # Bitbang on CBUS pins of R-type chips
SYNCFF = 0x40 # Single Channel Synchronous FIFO mode
[docs] def __init__(self,
mode: str,
serial_nr: str = None,
i2c_speed: float = 100E3,
spi_turbo: bool = False) -> None:
"""Checks the arguments validity, initializes the device and sets the locks.
Args:
mode (:obj:`str`): The communication mode, can be :
::
'SPI', 'I2C', 'GPIO_only', 'Write_serial_nr'
GPIOs can be driven in any mode, but faster speeds are achievable in
`GPIO_only` mode.
serial_nr (:obj:`str`, optional): The serial number of the FT232H to
drive. In `Write_serial_nr` mode, the serial number to be written.
i2c_speed (:obj:`str`, optional): In I2C mode, the I2C bus clock frequency
in Hz. Available values are :
::
100E3, 400E3, 1E6
or any value between `10kHz` and `100kHz`. Lowering below the default
value may solve I2C clock stretching issues on some devices.
spi_turbo (:obj:`str`, optional): Increases the achievable bus speed, but
may not work with some devices.
Note:
- **CS pin**:
The CS pin for selecting SPI devices is always `D3`. This pin is
reserved and cannot be used as a GPIO. If you want to drive the CS line
manually, it is possible not to drive the CS pin by setting the SPI
parameter :attr:`no_cs` to :obj:`True` and to drive the CS line from a
GPIO instead.
- ``mode``:
It is not possible to simultaneously control slaves over SPI and I2C,
due to different hardware requirements for the two protocols. Trying to
do so will most likely raise an error or lead to inconsistent behavior.
"""
if mode not in ft232h_modes:
raise ValueError("mode should be in {}".format(ft232h_modes))
self._ft232h_mode = mode
if mode == 'Write_serial_nr' and serial_nr is None:
raise ValueError("Cannot set serial number if it is not specified !")
if i2c_speed not in ft232h_i2c_speed:
try:
if not 10E3 <= i2c_speed < 100E3:
raise ValueError("i2c_speed should be in {} or between 10E3 and 100E3"
.format(list(ft232h_i2c_speed.values())))
except TypeError:
raise TypeError("i2c_speed should be a float or an int !")
self._gpio_low = 0
self._gpio_high = 0
self._gpio_dir = 0
self._retry_count = 8
self._usb_write_timeout = 5000
self._usb_read_timeout = 5000
self._serial_nr = serial_nr
self._turbo = spi_turbo
self._i2c_speed = i2c_speed
self._initialize()
if mode == 'Write_serial_nr':
self._set_serial_number(serial_nr)
self.close()
def _initialize(self) -> None:
"""Initializing the FT232H according to the chosen mode.
The main differences are for the choice of the clock frequency and
parameters.
"""
# FT232H properties
fifo_sizes = (1024, 1024)
latency = 16
# I2C properties
if self._ft232h_mode == 'I2C':
timings = ft232h_i2c_speed[self._i2c_speed if self._i2c_speed in
ft232h_i2c_speed else 100E3]
frequency = self._i2c_speed
self._ck_hd_sta = self._compute_delay_cycles(timings.t_hd_sta)
self._ck_su_sto = self._compute_delay_cycles(timings.t_su_sto)
ck_su_sta = self._compute_delay_cycles(timings.t_su_sta)
ck_buf = self._compute_delay_cycles(timings.t_buf)
self._ck_idle = max(ck_su_sta, ck_buf)
self._ck_delay = ck_buf
self._i2c_mask = ft232h_pins['SCL'] | ft232h_pins['SDAO'] | \
ft232h_pins['SDAI']
self._i2c_dir = ft232h_pins['SCL'] | ft232h_pins['SDAO']
# SPI properties
elif self._ft232h_mode == 'SPI':
frequency = 400E3
self._bits_per_word = 8
self._cshigh = False
self._no_cs = False
self._loop = False
self._lsbfirst = False
self._max_speed_hz = 400E3
self._mode = 0
self._threewire = False
self._spi_param_changed = True
self._cs_bit = ft232h_pins['CS']
self._spi_dir = self._cs_bit | ft232h_pins['SCK'] | ft232h_pins['DO']
self._spi_mask = self._cs_bit | ft232h_pins['SCK'] | \
ft232h_pins['DO'] | ft232h_pins['DI']
else:
frequency = 400E3
# Finding the matching USB devices
if self._serial_nr is not None and self._ft232h_mode != 'Write_serial_nr':
devices = find(find_all=True,
idVendor=Ftdi_vendor_id,
idProduct=ft232h_product_id,
custom_match=Find_serial_number(
self._serial_nr))
else:
devices = find(find_all=True,
idVendor=Ftdi_vendor_id,
idProduct=ft232h_product_id)
# Checking if there's only 1 device matching
devices = list(devices)
if len(devices) == 0:
raise IOError("No matching ft232h connected")
elif len(devices) > 1:
raise IOError("Several ft232h devices found, please specify a serial_nr")
else:
self._usb_dev = devices[0]
try:
self._serial_nr = self._usb_dev.serial_number
except ValueError:
self._serial_nr = ""
# Configuring the USB device, interface and endpoints
try:
if self._usb_dev.is_kernel_driver_active(0):
self._usb_dev.detach_kernel_driver(0)
self._usb_dev.set_configuration()
except USBError:
print("You may have to install the udev-rules for this USB device, "
"this can be done using the udev_rule_setter utility in the util "
"folder")
raise
config = self._usb_dev.get_active_configuration()
interface = config[(0, 0)]
self._index = interface.bInterfaceNumber + 1
endpoints = sorted([ep.bEndpointAddress for ep in interface])
self._in_ep, self._out_ep = endpoints[:2]
endpoint = interface[0]
self._max_packet_size = endpoint.wMaxPacketSize
# Invalidate data in the readbuffer
self._readoffset = 0
self._readbuffer = bytearray()
# Drain input buffer
self._purge_buffers()
# Shallow reset
if self._ctrl_transfer_out(ft232h_sio_req['reset'],
ft232h_sio_args['reset']):
raise IOError('Unable to reset FTDI device')
# Reset feature mode
self._set_bitmode(0, ft232h.BitMode.RESET)
# Set latency timer
self._set_latency_timer(latency)
# Set chunk size and invalidate all remaining data
self._writebuffer_chunksize = fifo_sizes[0]
self._readoffset = 0
self._readbuffer = bytearray()
self._readbuffer_chunksize = min(fifo_sizes[0], fifo_sizes[1],
self._max_packet_size)
# Reset feature mode
self._set_bitmode(0, ft232h.BitMode.RESET)
# Drain buffers
self._purge_buffers()
# Disable event and error characters
if self._ctrl_transfer_out(ft232h_sio_req['set_event_char'], 0):
raise IOError('Unable to set event char')
if self._ctrl_transfer_out(ft232h_sio_req['set_error_char'], 0):
raise IOError('Unable to set error char')
# Enable MPSSE mode
if self._ft232h_mode == 'GPIO_only':
self._set_bitmode(0xFF, ft232h.BitMode.BITBANG)
else:
self._set_bitmode(self._direction, ft232h.BitMode.MPSSE)
# Configure clock
if self._ft232h_mode == 'I2C':
# Note that bus frequency may differ from clock frequency, when
# 3-phase clock is enabled
self._set_frequency(3 * frequency / 2)
else:
self._set_frequency(frequency)
# Configure pins
if self._ft232h_mode == 'I2C':
cmd = bytearray(self._idle)
cmd.extend((ft232h_cmds['set_bits_high'], 0, 0))
self._write_data(cmd)
elif self._ft232h_mode == 'SPI':
cmd = bytearray((ft232h_cmds['set_bits_low'],
self._cs_bit & 0xFF,
self._direction & 0xFF))
cmd.extend((ft232h_cmds['set_bits_high'],
(self._cs_bit >> 8) & 0xFF,
(self._direction >> 8) & 0xFF))
self._write_data(cmd)
else:
cmd = bytearray((ft232h_cmds['set_bits_low'], 0, 0))
cmd.extend((ft232h_cmds['set_bits_high'], 0, 0))
self._write_data(cmd)
# Disable loopback
self._write_data(bytearray((ft232h_cmds['loopback_end'],)))
# Validate MPSSE
bytes_ = bytes(self._read_data_bytes(2))
if (len(bytes_) >= 2) and (bytes_[0] == '\xfa'):
raise IOError("Invalid command @ %d" % bytes_[1])
# I2C-specific settings
if self._ft232h_mode == 'I2C':
self._tx_size, self._rx_size = fifo_sizes
# Enable 3-phase clock
self._write_data(bytearray([True and
ft232h_cmds['enable_clk_3phase'] or
ft232h_cmds['disable_clk_3phase']]))
# Enable drivezero mode
self._write_data(bytearray([ft232h_cmds['drive_zero'],
self._i2c_mask & 0xFF,
(self._i2c_mask >> 8) & 0xFF]))
# Disable adaptative clock
self._write_data(bytearray([False and
ft232h_cmds['enable_clk_adaptative'] or
ft232h_cmds['disable_clk_adaptative']]))
@staticmethod
def _compute_delay_cycles(value: float) -> int:
"""Approximates the number of clock cycles over a given delay.
Args:
value (:obj:`float`): delay (in seconds)
Returns:
Number of clock cycles
"""
bit_delay = ft232h_mpsse_bit_delay
return max(1, int((value + bit_delay) / bit_delay))
def _set_latency_timer(self, latency: int) -> None:
"""Sets the latency timer.
Sets the latency timer, i.e. the delay the chip waits before sending the
data stored in the buffer to the host. Not applicable when a send
immediate command is issued, in which case the buffered data is returned
immediately.
Args:
latency (:obj:`int`): latency (in milliseconds)
"""
if not ft232h_latency['min'] <= latency <= ft232h_latency['max']:
raise ValueError("Latency out of range")
if self._ctrl_transfer_out(ft232h_sio_req['set_latency_timer'], latency):
raise IOError('Unable to set latency timer')
def _set_frequency(self, frequency: float) -> float:
"""Sets the bus frequency.
Sets the FT232H clock divisor value, according to the desired bus
frequency. The actual bus frequency is then as close as possible to the
desired value, but may still be slightly different.
Args:
frequency (:obj:`float`): Desired bus frequency (in Hz)
Returns:
Actual bus frequency
"""
# Calculate base speed clock divider
divcode = ft232h_cmds['enable_clk_div5']
divisor = int((ft232h_clock['base'] + frequency / 2) / frequency) - 1
divisor = max(0, min(0xFFFF, divisor))
actual_freq = ft232h_clock['base'] / (divisor + 1)
error = (actual_freq / frequency) - 1
# Calculate high speed clock divider
divisor_hs = int((ft232h_clock['high'] + frequency / 2) / frequency) - 1
divisor_hs = max(0, min(0xFFFF, divisor_hs))
actual_freq_hs = ft232h_clock['high'] / (divisor_hs + 1)
error_hs = (actual_freq_hs / frequency) - 1
# Enable if closer to desired frequency
# =====================================================================
if abs(error_hs) <= abs(error):
divcode = ft232h_cmds['disable_clk_div5']
divisor = divisor_hs
actual_freq = actual_freq_hs
# FTDI expects little endian
cmd = bytearray((divcode,))
cmd.extend((ft232h_cmds['set_tck_divisor'], divisor & 0xff,
(divisor >> 8) & 0xff))
cmd.extend((ft232h_cmds['send_immediate'],))
self._write_data(cmd)
# validate MPSSE
bytes_ = bytes(self._read_data_bytes(2))
if (len(bytes_) >= 2) and (bytes_[0] == '\xfa'):
raise IOError("Invalid command @ %d" % bytes_[1])
# Drain input buffer
self._purge_rx_buffer()
return actual_freq
def _set_bitmode(self, bitmask: int, mode: BitMode) -> None:
"""Sets the bitbang mode.
Args:
bitmask (:obj:`int`): Mask for choosing the driven GPIOs.
mode (:class:`BitMode`): Bitbang mode to be set.
"""
mask = sum(ft232h.BitMode)
value = (bitmask & 0xff) | ((mode.value & mask) << 8)
if self._ctrl_transfer_out(ft232h_sio_req['set_bitmode'], value):
raise IOError('Unable to set bitmode')
def _purge_buffers(self) -> None:
"""Clears the buffers on the chip and the internal read buffer."""
self._purge_rx_buffer()
self._purge_tx_buffer()
def _purge_rx_buffer(self) -> None:
"""Clears the USB receive buffer on the chip (host-to-ftdi) and the
internal read buffer."""
if self._ctrl_transfer_out(ft232h_sio_req['reset'],
ft232h_sio_args['purge_RX']):
raise IOError('Unable to flush RX buffer')
# Invalidate data in the readbuffer
self._readoffset = 0
self._readbuffer = bytearray()
def _purge_tx_buffer(self) -> None:
"""Clears the USB transmit buffer on the chip (ftdi-to-host)."""
if self._ctrl_transfer_out(ft232h_sio_req['reset'],
ft232h_sio_args['purge_TX']):
raise IOError('Unable to flush TX buffer')
def _ctrl_transfer_out(self,
reqtype: int,
value: int,
data: bytes = b'') -> int:
"""Sends a control message to the device.
Args:
reqtype (:obj:`int`): bmRequest
value (:obj:`int`): wValue
data (:obj:`bytes`): payload
Returns:
Number of bytes actually written
"""
try:
return self._usb_dev.ctrl_transfer(
Ftdi_req_out, reqtype, value, self._index,
bytearray(data), self._usb_write_timeout)
except USBError as ex:
raise IOError('UsbError: %s' % str(ex))
def _set_serial_number(self, serial_number: str) -> None:
"""(Over)Writes the serial number.
Writes the desired serial number to the EEPROM. It is then accessible to
USB commands as a string descriptor. Also sets the manufacturer and
product string descriptors.
Args:
serial_number (:obj:`str`): Serial number to be written in the EEPROM
"""
if not isinstance(serial_number, str):
serial_number = str(serial_number)
if any(char in serial_number for char in ':/'):
raise ValueError("Invalid character : or / in serial number")
# Reading current eeprom
word_count = round(ft232h_eeprom_size / 2)
word_addr = 0
data = bytearray()
while word_count:
try:
buf = self._usb_dev.ctrl_transfer(
Ftdi_req_in, ft232h_sio_req['read_eeprom'], 0,
word_addr, 2, self._usb_read_timeout)
except USBError as exc:
raise IOError('UsbError: %s' % exc) from exc
if not buf:
raise IOError('EEPROM read error @ %d' % (word_addr << 1))
data.extend(buf)
word_count -= 1
word_addr += 1
new_eeprom = data[0:ft232h_eeprom_size]
# Setting the has_serial flag to True
new_eeprom[ft232h_eeprom['has_serial_pos']] |= 1 << 3
# Changing the string descriptors and the descriptors index
str_descriptors = {'manufacturer': 'FTDI',
'product': 'FT232H',
'serial': serial_number}
stream = bytearray()
str_pos = ft232h_eeprom['str_position']
tbl_pos = ft232h_eeprom['str_table']
data_pos = str_pos
for name in str_descriptors:
new_str = str_descriptors[name].encode('utf-16le')
length = len(new_str) + 2
stream.append(length)
stream.append(util.DESC_TYPE_STRING) # string descriptor
stream.extend(new_str)
new_eeprom[tbl_pos] = data_pos
tbl_pos += 1
new_eeprom[tbl_pos] = length
tbl_pos += 1
data_pos += length
new_eeprom[str_pos:str_pos + len(stream)] = stream
# Filling the remaining space with zeros
crc_pos = len(new_eeprom)
rem = crc_pos - (str_pos + len(stream))
new_eeprom[str_pos + len(stream):crc_pos] = bytes(rem)
# Checking the eeprom length
if len(new_eeprom) != ft232h_eeprom_size:
raise ValueError("Eeprom_size not matching, serial number may be "
"too long, eeprom not written")
# Calculating the new checksum and modifying the corresponding bytes
checksum = 0xAAAA
for idx in range(0, len(new_eeprom[:-2]), 2):
v = ((new_eeprom[:-2][idx + 1] << 8) + new_eeprom[:-2][idx]) & 0xFFFF
checksum = v ^ checksum
checksum = ((checksum << 1) & 0xFFFF) | ((checksum >> 15) & 0xFFFF)
new_eeprom[-2] = checksum & 0xFF
new_eeprom[-1] = checksum >> 8
# Updating the eeprom
addr = 0
for word in unpack('<%dH' % (len(new_eeprom) // 2), new_eeprom):
out = self._usb_dev.ctrl_transfer(
Ftdi_req_out, ft232h_sio_req['write_eeprom'],
word, addr >> 1, b'', self._usb_write_timeout)
if out:
raise IOError('EEPROM Write Error @ %d' % addr)
addr += 2
def _write_data(self, data: Union[bytearray, bytes]) -> int:
"""Writes data to the FT232H.
Writes the sequence of MPSSE commands and data to the FTDI port. Data
buffer is split into chunk-sized blocks before being sent over the USB bus.
Args:
data: The byte stream to send to the FTDI interface
Returns:
Count of written bytes
"""
offset = 0
size = len(data)
try:
while offset < size:
write_size = self._writebuffer_chunksize
if offset + write_size > size:
write_size = size - offset
try:
length = self._usb_dev.write(self._in_ep,
data[offset:offset + write_size],
self._usb_write_timeout)
except USBError:
raise
if length <= 0:
raise USBError("Usb bulk write error")
offset += length
return offset
except USBError:
print("An error occurred while writing to USB")
raise
def _read_data_bytes(self,
size: int,
attempt: int = 2,
request_gen: Callable = None) -> bytes:
"""Reads data from the FT232H.
Reads data from the FTDI interface. The data buffer is rebuilt from
chunk-sized blocks received over the USB bus. The FTDI device always sends
internal status bytes, which are stripped out as not part of the data
payload.
Args:
size (:obj:`int`): The number of bytes to receive from the device
attempt (:obj:`int`): Attempt cycle count
request_gen: A callable that takes the number of bytes read and expects a
bytes buffer to send back to the remote device. This is only useful to
perform optimized/continuous transfer from a slave device.
Returns:
Payload bytes
"""
# Packet size sanity check
if not self._max_packet_size:
raise ValueError("max_packet_size is bogus")
packet_size = self._max_packet_size
length = 1 # initial condition to enter the usb_read loop
data = bytearray()
# everything we want is still in the cache?
if size <= len(self._readbuffer) - self._readoffset:
data = self._readbuffer[self._readoffset:self._readoffset + size]
self._readoffset += size
return data
# something still in the cache, but not enough to satisfy 'size'?
if len(self._readbuffer) - self._readoffset != 0:
data = self._readbuffer[self._readoffset:]
# end of readbuffer reached
self._readoffset = len(self._readbuffer)
# read from USB, filling in the local cache as it is empty
retry = attempt
req_size = size
try:
while (len(data) < size) and (length > 0):
while True:
try:
tempbuf = self._usb_dev.read(self._out_ep,
self._readbuffer_chunksize,
self._usb_read_timeout)
except USBError:
raise
retry -= 1
length = len(tempbuf)
# the received buffer contains at least one useful databyte
# (first 2 bytes in each packet represent the current modem
# status)
if length >= 2:
if tempbuf[1] & ft232h_tx_empty_bits:
if request_gen:
req_size -= length - 2
if req_size > 0:
cmd = request_gen(req_size)
if cmd:
self._write_data(cmd)
if length > 2:
retry = attempt
# skip the status bytes
chunks = (length + packet_size - 1) // packet_size
count = packet_size - 2
self._readbuffer = bytearray()
self._readoffset = 0
srcoff = 2
for _ in range(chunks):
self._readbuffer += tempbuf[srcoff:srcoff + count]
srcoff += packet_size
length = len(self._readbuffer)
break
# received buffer only contains the modem status bytes
# no data received, may be late, try again
if retry > 0:
continue
# no actual data
self._readbuffer = bytearray()
self._readoffset = 0
# no more data to read?
return data
if length > 0:
# data still fits in buf?
if (len(data) + length) <= size:
data += self._readbuffer[self._readoffset:
self._readoffset + length]
self._readoffset += length
# did we read exactly the right amount of bytes?
if len(data) == size:
return data
else:
# partial copy, not enough bytes in the local cache to
# fulfill the request
part_size = min(size - len(data),
len(self._readbuffer) - self._readoffset)
if part_size < 0:
raise ValueError("Internal Error")
data += self._readbuffer[self._readoffset:
self._readoffset + part_size]
self._readoffset += part_size
return data
except USBError:
print("An error occurred while writing to USB")
raise
# never reached
raise ValueError("Internal error")
@property
def _clk_hi_data_lo(self) -> tuple:
"""Returns the MPSSE command for driving CLK line high and SDA line low,
while preserving the GPIO outputs."""
return (ft232h_cmds['set_bits_low'],
ft232h_pins['SCL'] | self._gpio_low,
self._i2c_dir | (self._gpio_dir & 0xFF))
@property
def _clk_lo_data_input(self) -> tuple:
"""Returns the MPSSE command for driving CLK line low and listening to SDA
line, while preserving the GPIO outputs."""
return (ft232h_cmds['set_bits_low'],
self._gpio_low,
ft232h_pins['SCL'] | (self._gpio_dir & 0xFF))
@property
def _clk_lo_data_hi(self) -> tuple:
"""Returns the MPSSE command for driving CLK line low and SDA line high,
while preserving the GPIO outputs."""
return (ft232h_cmds['set_bits_low'],
ft232h_pins['SDAO'] | self._gpio_low,
self._i2c_dir | (self._gpio_dir & 0xFF))
@property
def _clk_lo_data_lo(self) -> tuple:
"""Returns the MPSSE command for driving CLK line low and SDA line low,
while preserving the GPIO outputs."""
return (ft232h_cmds['set_bits_low'],
self._gpio_low,
self._i2c_dir | (self._gpio_dir & 0xFF))
@property
def _idle(self) -> tuple:
"""Returns the MPSSE command for driving CLK line high and SDA line high,
while preserving the GPIO outputs."""
return (ft232h_cmds['set_bits_low'],
self._i2c_dir | self._gpio_low,
self._i2c_dir | (self._gpio_dir & 0xFF))
@property
def _start(self) -> tuple:
"""Returns the MPSSE command for issuing and I2C start condition."""
return self._clk_hi_data_lo * self._ck_hd_sta + \
self._clk_lo_data_lo * self._ck_hd_sta
@property
def _stop(self) -> tuple:
"""Returns the MPSSE command for issuing and I2C stop condition."""
return self._clk_lo_data_hi * self._ck_hd_sta + \
self._clk_lo_data_lo * self._ck_hd_sta + \
self._clk_hi_data_lo * self._ck_su_sto + \
self._idle * self._ck_idle
def _do_prolog(self, i2caddress: int) -> None:
"""Sends the MPSSE commands for starting an I2C transaction.
Args:
i2caddress (:obj:`int`): I2C address of the slave
"""
if i2caddress is None:
return
cmd = bytearray(self._idle * self._ck_delay)
cmd.extend(self._start)
cmd.extend((ft232h_cmds['write_bytes_NVE_MSB'], 0, 0))
cmd.append(i2caddress)
try:
self._send_check_ack(cmd)
except IOError:
raise
def _do_write(self, out: list) -> None:
"""Sends the MPSSE commands for writing bytes to an I2C slave.
Args:
out (:obj:`list`): List of bytes to write
"""
if not isinstance(out, bytearray):
out = bytearray(out)
if not out:
return
for byte in out:
cmd = bytearray((ft232h_cmds['write_bytes_NVE_MSB'], 0, 0))
cmd.append(byte)
self._send_check_ack(cmd)
def _do_read(self, readlen: int) -> bytearray:
"""
Sends the MPSSE commands for reading bytes from an I2C slave, and then
returns these bytes.
Args:
readlen: Number of bytes to read
Returns: Read bytes as a bytearray
"""
if not readlen:
# force a real read request on device, but discard any result
cmd = bytearray()
cmd.extend((ft232h_cmds['send_immediate'],))
self._write_data(cmd)
self._read_data_bytes(0, 8)
return bytearray()
ack = (ft232h_cmds['write_bits_NVE_MSB'], 0, 0)
nack = (ft232h_cmds['write_bits_NVE_MSB'], 0, 0xFF)
read_not_last = ((ft232h_cmds['read_bytes_PVE_MSB'], 0, 0) + ack +
self._clk_lo_data_hi * self._ck_delay)
read_last = ((ft232h_cmds['read_bytes_PVE_MSB'], 0, 0) + nack +
self._clk_lo_data_hi * self._ck_delay)
# maximum RX size to fit in FTDI FIFO, minus 2 status bytes
chunk_size = self._rx_size - 2
cmd_size = len(read_last)
# limit RX chunk size to the count of I2C packable commands in the FTDI
# TX FIFO (minus one byte for the last 'send immediate' command)
tx_count = (self._tx_size - 1) // cmd_size
chunk_size = min(tx_count, chunk_size)
chunks = []
rem = readlen
if rem > chunk_size:
chunk_size //= 2
cmd_chunk = bytearray()
cmd_chunk.extend(read_not_last * chunk_size)
cmd_chunk.extend((ft232h_cmds['send_immediate'],))
def _write_command_gen(length: int) -> Union[bytearray, bytes]:
if length <= 0:
# no more data
return b''
if length <= chunk_size:
cmd_ = bytearray()
cmd_.extend(read_not_last * (length - 1))
cmd_.extend(read_last)
cmd_.extend((ft232h_cmds['send_immediate'],))
return cmd_
return cmd_chunk
while rem:
buf = self._read_data_bytes(rem, 8, _write_command_gen)
chunks.append(buf)
rem -= len(buf)
else:
cmd = bytearray()
cmd.extend(read_not_last * (rem - 1))
cmd.extend(read_last)
cmd.extend((ft232h_cmds['send_immediate'],))
size = rem
self._write_data(cmd)
buf = self._read_data_bytes(size, 8)
chunks.append(buf)
return bytearray(b''.join(chunks))
def _send_check_ack(self, cmd: bytearray) -> None:
"""Actually sends the MPSSE commands generated by :meth:`_do_prolog` and
:meth:`_do_write` methods, and checks whether the slave ACKs it.
Args:
cmd (:obj:`bytearray`): The MPSSE commands to send
"""
# SCL low, SDA high-Z
cmd.extend(self._clk_lo_data_hi)
# read SDA (ack from slave)
cmd.extend((ft232h_cmds['read_bits_PVE_MSB'], 0))
cmd.extend((ft232h_cmds['send_immediate'],))
self._write_data(cmd)
ack = self._read_data_bytes(1, 8)
if not ack:
raise IOError('No answer from FTDI')
if ack[0] & 0x01:
raise IOError('NACK from slave')
def _write_i2c(self, address: int, out: list) -> None:
"""Writes bytes to an I2C slave.
Args:
address (:obj:`int`): I2C address of the slave
out (:obj:`list`): List of bytes to send
"""
i2caddress = (address << 1) & 0xFF
retries = self._retry_count
while True:
try:
self._do_prolog(i2caddress)
self._do_write(out)
return
except IOError:
retries -= 1
if not retries:
raise
finally:
self._write_data(bytearray(self._stop))
def _exchange_i2c(self,
address: int,
out: list,
readlen: int = 0) -> bytearray:
"""Writes bytes to an I2C slave, and then reads a given number of bytes
from this same slave.
Args:
address (:obj:`int`): I2C address of the slave
out (:obj:`list`): List of bytes to send
readlen (:obj:`int`): Number of bytes to read
Returns:
Read bytes as a bytearray
"""
if readlen < 1:
raise IOError('Nothing to read')
if readlen > (ft232h_max_payload / 3 - 1):
raise IOError("Input payload is too large")
if address is None:
i2caddress = None
else:
i2caddress = (address << 1) & 0xFF
retries = self._retry_count
while True:
try:
self._do_prolog(i2caddress)
self._do_write(out)
self._do_prolog(i2caddress | 0x01)
data = self._do_read(readlen)
return data
except IOError:
retries -= 1
if not retries:
raise
finally:
self._write_data(bytearray(self._stop))
[docs] def write_byte(self, i2c_addr: int, value: int) -> None:
"""Writes a single byte to an I2C slave, in register 0.
Args:
i2c_addr (:obj:`int`): I2C address of the slave
value (:obj:`int`): The value to write
"""
self.write_i2c_block_data(i2c_addr=i2c_addr,
register=0x00,
data=[value & 0xFF])
[docs] def write_byte_data(self, i2c_addr: int, register: int, value: int) -> None:
"""Writes a single byte to an I2C slave, in the specified register.
Args:
i2c_addr (:obj:`int`): I2C address of the slave
register (:obj:`int`): Index of the register to be written
value (:obj:`int`): The value to write
"""
self.write_i2c_block_data(i2c_addr=i2c_addr,
register=register,
data=[value & 0xFF])
[docs] def write_word_data(self, i2c_addr: int, register: int, value: int) -> None:
"""Writes 2 bytes to an I2C slave from a single int value, starting at the
specified register.
Depending on the size of the registers, the next register may be written as
well.
Args:
i2c_addr (:obj:`int`): I2C address of the slave
register (:obj:`int`): Index of the first register to be written
value (:obj:`int`): The value to write
"""
self.write_i2c_block_data(i2c_addr=i2c_addr,
register=register,
data=[(value >> 8) & 0xFF, value & 0xFF])
[docs] def write_block_data(self, i2c_addr: int, register: int, data: list) -> None:
"""Actually calls :meth:`write_i2c_block_data`.
Args:
i2c_addr (:obj:`int`): I2C address of the slave
register (:obj:`int`): Index of the first register to be written
data (:obj:`list`): List of bytes to write
"""
self.write_i2c_block_data(i2c_addr=i2c_addr,
register=register,
data=data)
[docs] def write_i2c_block_data(self,
i2c_addr: int,
register: int,
data: list) -> None:
"""Writes bytes from a :obj:`list` to an I2C slave, starting at the
specified register.
Args:
i2c_addr (:obj:`int`): I2C address of the slave
register (:obj:`int`): Index of the first register to be written
data (:obj:`list`): List of bytes to write
"""
if self._ft232h_mode != 'I2C':
raise ValueError("Method only available in I2C mode")
if not 0 <= i2c_addr <= 127:
raise ValueError("Incorrect i2c address, should be between 0 and 127")
self._write_i2c(address=i2c_addr,
out=[register] + data)
[docs] def read_byte(self, i2c_addr: int) -> int:
"""Reads a single byte from an I2C slave, from the register `0`.
Args:
i2c_addr (:obj:`int`): I2C address of the slave
Returns:
Value of the read register
"""
try:
return self.read_i2c_block_data(i2c_addr=i2c_addr,
register=0x00,
length=1)[0]
except IndexError:
print("No data to read")
raise
[docs] def read_byte_data(self, i2c_addr: int, register: int) -> int:
"""Reads a single byte from an I2C slave, from the specified register.
Args:
i2c_addr (:obj:`int`): I2C address of the slave
register (:obj:`int`): Index of the register to be read
Returns:
Value of the read register
"""
try:
return self.read_i2c_block_data(i2c_addr=i2c_addr,
register=register,
length=1)[0]
except IndexError:
print("No data to read")
raise
[docs] def read_word_data(self, i2c_addr: int, register: int) -> int:
"""Reads 2 bytes from an I2C slave, starting at the specified register, and
returns them as one single value.
Args:
i2c_addr (:obj:`int`): I2C address of the slave
register (:obj:`int`): Index of the first register to be read
Returns:
Value of the read registers
"""
try:
ret = self.read_i2c_block_data(i2c_addr=i2c_addr,
register=register,
length=2)
return (ret[0] << 8) & ret[1]
except IndexError:
print("Not enough data to read")
raise
[docs] def read_i2c_block_data(self,
i2c_addr: int,
register: int,
length: int) -> list:
"""Reads a given number of bytes from an I2C slave, starting at the
specified register.
Args:
i2c_addr (:obj:`int`): I2C address of the slave
register (:obj:`int`): Index of the first register to be read
length (:obj:`int`): Number of bytes to read
Returns:
Values of read registers as a :obj:`list`
"""
if self._ft232h_mode != 'I2C':
raise ValueError("Method only available in I2C mode")
if not 0 <= i2c_addr <= 127:
raise ValueError("Incorrect i2c address, should be between 0 and 127")
if not length >= 0:
raise ValueError("length should be a positive integer")
if length == 0:
return []
return [byte for byte in self._exchange_i2c(address=i2c_addr,
out=[register],
readlen=length)]
@property
def bits_per_word(self) -> int:
"""Number of bits per SPI words.
Can only be set to 8.
"""
if self._ft232h_mode != 'SPI':
raise ValueError("Attribute only available in SPI mode")
return self._bits_per_word
@bits_per_word.setter
def bits_per_word(self, value: int) -> None:
if self._ft232h_mode != 'SPI':
raise ValueError("Attribute only available in SPI mode")
if not isinstance(value, int):
raise TypeError("bits_per_word should be an integer")
if value != 8:
raise ValueError("bits_per_word values other than 8 are not implemented")
self._bits_per_word = value
@property
def cshigh(self) -> bool:
"""If :obj:`True`, the polarity of the CS line is inverted."""
if self._ft232h_mode != 'SPI':
raise ValueError("Attribute only available in SPI mode")
return self._cshigh
@cshigh.setter
def cshigh(self, value: bool) -> None:
if self._ft232h_mode != 'SPI':
raise ValueError("Attribute only available in SPI mode")
if not isinstance(value, bool):
raise TypeError("cshigh should be either True or False")
self._spi_param_changed = True
self._cshigh = value
@property
def loop(self) -> bool:
"""If :obj:`True`, the loopback mode is enabled."""
if self._ft232h_mode != 'SPI':
raise ValueError("Attribute only available in SPI mode")
return self._loop
@loop.setter
def loop(self, value: bool) -> None:
if self._ft232h_mode != 'SPI':
raise ValueError("Attribute only available in SPI mode")
if not isinstance(value, bool):
raise TypeError("loop should be either True or False")
if value:
self._write_data(bytearray((ft232h_cmds['loopback_start'],)))
else:
self._write_data(bytearray((ft232h_cmds['loopback_end'],)))
self._loop = value
@property
def no_cs(self) -> bool:
"""If :obj:`True`, the CS line is not driven."""
if self._ft232h_mode != 'SPI':
raise ValueError("Attribute only available in SPI mode")
return self._no_cs
@no_cs.setter
def no_cs(self, value: bool) -> None:
if self._ft232h_mode != 'SPI':
raise ValueError("Attribute only available in SPI mode")
if not isinstance(value, bool):
raise TypeError("no_cs should be either True or False")
self._no_cs = value
@property
def lsbfirst(self) -> bool:
"""If :obj:`True`, data is sent and received LSB first."""
if self._ft232h_mode != 'SPI':
raise ValueError("Attribute only available in SPI mode")
return self._lsbfirst
@lsbfirst.setter
def lsbfirst(self, value: bool) -> None:
if self._ft232h_mode != 'SPI':
raise ValueError("Attribute only available in SPI mode")
if not isinstance(value, bool):
raise TypeError("lsbfirst should be either True or False")
self._lsbfirst = value
@property
def max_speed_hz(self) -> float:
"""The SPI bus clock frequency in Hz.
In SPI modes `1` and `3`, the actual bus clock frequency is 50% higher than
the input value because the FT232H is switched to 3-phase clock mode.
"""
if self._ft232h_mode != 'SPI':
raise ValueError("Attribute only available in SPI mode")
return self._max_speed_hz
@max_speed_hz.setter
def max_speed_hz(self, value: float) -> None:
if self._ft232h_mode != 'SPI':
raise ValueError("Attribute only available in SPI mode")
if self.mode in [1, 3]:
if not 3200 <= value <= 2 * ft232h_clock['high'] / 3:
raise ValueError("max_speed_hz should be between 3.2kHz and 20MHz in "
"spi modes 1 and 3")
else:
if not 4800 <= value <= ft232h_clock['high']:
raise ValueError("max_speed_hz should be between 4.8kHz and 30MHz in "
"spi modes 0 and 2")
self._spi_param_changed = True
if self.mode in [1, 3]:
self._set_frequency(3 * value / 2)
self._write_data(bytearray([True and
ft232h_cmds['enable_clk_3phase'] or
ft232h_cmds['disable_clk_3phase']]))
else:
self._set_frequency(value)
self._write_data(bytearray([False and
ft232h_cmds['enable_clk_3phase'] or
ft232h_cmds['disable_clk_3phase']]))
self._max_speed_hz = value
@property
def mode(self) -> int:
"""The SPI mode used for communicating with the slave.
When changing the SPI mode, the bus clock frequency may be reloaded.
"""
if self._ft232h_mode != 'SPI':
raise ValueError("Attribute only available in SPI mode")
return self._mode
@mode.setter
def mode(self, value: int) -> None:
if self._ft232h_mode != 'SPI':
raise ValueError("Attribute only available in SPI mode")
if value not in range(4):
raise ValueError("mode should be an integer between 0 and 3")
former_mode = self.mode
self._mode = value
self._spi_param_changed = True
if value % 2 != former_mode % 2:
self.max_speed_hz = self.max_speed_hz
@property
def threewire(self) -> bool:
"""If :obj:`True`, indicates that the MISO and MOSI lines are connected
together. Not currently implemented."""
if self._ft232h_mode != 'SPI':
raise ValueError("Attribute only available in SPI mode")
return self._threewire
@threewire.setter
def threewire(self, value: bool) -> None:
if self._ft232h_mode != 'SPI':
raise ValueError("Attribute only available in SPI mode")
if not isinstance(value, bool):
raise TypeError("threewire should be either True or False")
if value:
raise ValueError("threewire mode not implemented")
self._threewire = value
def _exchange_spi(self, readlen: int, out: list, start: bool,
stop: bool, duplex: bool) -> bytes:
"""Exchanges bytes with an SPI slave.
Can read and/or write data, in a sequential or simultaneous way. Also
manages the CS line.
Args:
readlen (:obj:`int`): Number of bytes to read. If 0, no reading is
performed.
out (:obj:`list`): List of bytes to write. If empty, no writing is
performed.
start (:obj:`bool`): If :obj:`False`, the CS line is not driven before
exchanging data, and remains in its previous state.
stop (:obj:`bool`): If :obj:`False`, the CS line is not driven after
exchanging data, and remains in its previous state.
duplex (:obj:`int`): If :obj:`True`, the data is read and written
simultaneously. If :obj:`False`, writes then reads in a sequential way.
Returns:
Read data as bytes
"""
if len(out) > ft232h_max_payload:
raise IOError("Output payload is too large")
if readlen > ft232h_max_payload:
raise IOError("Input payload is too large")
if not isinstance(out, bytearray):
out = bytearray(out)
# Re-building the _cs_prolog and _cs_epilog if an SPI parameter has been
# modified
if self._spi_param_changed:
cs_hold = 1 + int(1E6 / self.max_speed_hz)
self._cpol = self.mode & 0x2
cs_clock = 0xFFFF & ~((~self._cpol & ft232h_pins['SCK']) |
ft232h_pins['DO'] |
(self.cshigh and self._cs_bit))
cs_select = 0xFFFF & ~((~self._cpol & ft232h_pins['SCK']) |
ft232h_pins['DO'] |
((not self.cshigh) and self._cs_bit))
self._cs_prolog = [cs_clock, cs_select]
self._cs_epilog = [cs_select] + [cs_clock] * cs_hold
self._spi_param_changed = False
# Building the prolog MPSSE command
cmd = bytearray()
if start:
for ctrl in self._cs_prolog:
ctrl &= self._spi_mask
ctrl |= self._gpio_low
ctrl |= self._gpio_high << 8
cmd.extend((ft232h_cmds['set_bits_low'], ctrl & 0xFF,
self._direction & 0xFF))
# Building the epilog MPSSE command
epilog = bytearray()
for ctrl in self._cs_epilog:
ctrl &= self._spi_mask
ctrl |= self._gpio_low
ctrl |= self._gpio_high << 8
epilog.extend((ft232h_cmds['set_bits_low'], ctrl & 0xFF,
self._direction & 0xFF))
# Restore idle state
if not self.cshigh:
cs_high = [ft232h_cmds['set_bits_low'], self._cs_bit |
self._gpio_low & 0xFF,
self._direction & 0xFF]
else:
cs_high = [ft232h_cmds['set_bits_low'], self._gpio_low & 0xFF,
self._direction & 0xFF]
if not self._turbo:
cs_high.append(ft232h_cmds['send_immediate'])
epilog.extend(cs_high)
# Sequential communication
if not duplex:
# Write MPSSE commands
writelen = len(out)
if writelen:
if not self.lsbfirst:
wcmd = (ft232h_cmds['write_bytes_NVE_MSB'] if not self._cpol else
ft232h_cmds['write_bytes_PVE_MSB'])
else:
wcmd = (ft232h_cmds['write_bytes_NVE_LSB'] if not self._cpol else
ft232h_cmds['write_bytes_PVE_LSB'])
write_cmd = pack('<BH', wcmd, writelen - 1)
cmd.extend(write_cmd)
cmd.extend(out)
# Read MPSSE commands
if readlen:
if not self.lsbfirst:
rcmd = (ft232h_cmds['read_bytes_NVE_MSB'] if not self._cpol else
ft232h_cmds['read_bytes_PVE_MSB'])
else:
rcmd = (ft232h_cmds['read_bytes_NVE_LSB'] if not self._cpol else
ft232h_cmds['read_bytes_PVE_LSB'])
read_cmd = pack('<BH', rcmd, readlen - 1)
cmd.extend(read_cmd)
# ====================================================================
if self._turbo:
cmd.extend((ft232h_cmds['send_immediate'],))
if self._turbo:
if stop:
cmd.extend(epilog)
self._write_data(cmd)
else:
self._write_data(cmd)
if stop:
self._write_data(epilog)
# USB read cycle may occur before the FTDI device has actually
# sent the data, so try to read more than once if no data is
# actually received
data = self._read_data_bytes(readlen, 8)
# If nothing to read
else:
if writelen:
if self._turbo:
if stop:
cmd.extend(epilog)
self._write_data(cmd)
else:
self._write_data(cmd)
if stop:
self._write_data(epilog)
data = bytearray()
# Simultaneous communication
else:
if readlen > len(out):
tmp = bytearray(out)
tmp.extend([0] * (readlen - len(out)))
out = tmp
exlen = len(out)
if not self.lsbfirst:
wcmd = (ft232h_cmds['rw_bytes_PVE_NVE_MSB'] if not self._cpol else
ft232h_cmds['rw_bytes_NVE_PVE_MSB'])
else:
wcmd = (ft232h_cmds['rw_bytes_PVE_NVE_LSB'] if not self._cpol else
ft232h_cmds['rw_bytes_NVE_PVE_LSB'])
write_cmd = pack('<BH', wcmd, exlen - 1)
cmd.extend(write_cmd)
cmd.extend(out)
# ======================================================================
if self._turbo:
cmd.extend((ft232h_cmds['send_immediate'],))
if self._turbo:
if stop:
cmd.extend(epilog)
self._write_data(cmd)
else:
self._write_data(cmd)
if stop:
self._write_data(epilog)
# USB read cycle may occur before the FTDI device has actually
# sent the data, so try to read more than once if no data is
# actually received
data = self._read_data_bytes(exlen, 8)
return data
[docs] def readbytes(self, len: int, start: bool = True, stop: bool = True) -> list:
"""Reads the specified number of bytes from an SPI slave.
Args:
len (:obj:`int`): Number of bytes to read
start (:obj:`bool`): If :obj:`False`, the CS line is not driven before
reading data, and remains in its previous state.
stop (:obj:`bool`): If :obj:`False`, the CS line is not driven after
reading data, and remains in its previous state.
Returns:
List of read bytes
"""
if self._ft232h_mode != 'SPI':
raise ValueError("Method only available in SPI mode")
return [byte for byte in self._exchange_spi(readlen=len,
out=[],
start=start,
stop=stop,
duplex=False)]
[docs] def writebytes(self,
values: list,
start: bool = True,
stop: bool = True) -> None:
"""Write bytes from a list to an SPI slave.
Args:
values (:obj:`list`): List of bytes to write
start (:obj:`bool`): If :obj:`False`, the CS line is not driven before
reading data, and remains in its previous state.
stop (:obj:`bool`): If :obj:`False`, the CS line is not driven after
reading data, and remains in its previous state.
"""
if self._ft232h_mode != 'SPI':
raise ValueError("Method only available in SPI mode")
self._exchange_spi(readlen=0,
out=values,
start=start,
stop=stop,
duplex=False)
[docs] def writebytes2(self,
values: list,
start: bool = True,
stop: bool = True) -> None:
"""Actually calls the :meth:`writebytes` method with the same arguments."""
self.writebytes(values=values,
start=start,
stop=stop)
[docs] def xfer(self,
values: list,
speed: float = None,
delay: float = 0.0,
bits: int = 8,
start: bool = True,
stop: bool = True) -> list:
"""Simultaneously reads and write bytes to an SPI slave.
The number of bytes to read is equal to the number of bytes in the write
buffer.
Args:
values (:obj:`list`): List of bytes to write
speed (:obj:`float`): Sets the bus clock frequency before issuing the
command (in Hz)
delay (:obj:`float`): Not implemented, should be 0.0
bits (:obj:`int`): Not implemented, should be 8
start (:obj:`bool`): If :obj:`False`, the CS line is not driven before
reading data, and remains in its previous state.
stop (:obj:`bool`): If :obj:`False`, the CS line is not driven after
reading data, and remains in its previous state.
Returns:
List of read bytes
"""
if self._ft232h_mode != 'SPI':
raise ValueError("Method only available in SPI mode")
if bits != 8:
raise ValueError("Only bits=8 is implemented")
if delay != 0.0:
raise ValueError("The delay parameter is not currently implemented")
if speed != self.max_speed_hz and speed is not None:
self.max_speed_hz = speed
return [byte for byte in self._exchange_spi(readlen=len(values),
out=values,
start=start,
stop=stop,
duplex=True)]
[docs] def xfer2(self,
values: list,
speed: float = 6.0E6,
delay: float = 0.0,
bits: int = 8,
start: bool = True,
stop: bool = True) -> list:
"""Actually calls the :meth:`xfer` method with the same arguments."""
return self.xfer(values=values,
speed=speed,
delay=delay,
bits=bits,
start=start,
stop=stop)
[docs] def xfer3(self,
values: list,
speed: float = 6.0E6,
delay: float = 0.0,
bits: int = 8,
start: bool = True,
stop: bool = True) -> list:
"""Actually calls the :meth:`xfer` method with the same arguments."""
return self.xfer(values=values,
speed=speed,
delay=delay,
bits=bits,
start=start,
stop=stop)
@property
def _gpio_all_pins(self) -> int:
"""Reports the addressable GPIOs as a bitfield.
A :obj:`True` bit represents a pin which may be used as a GPIO, a
:obj:`False` bit a reserved pin.
Returns:
Bitfield of configurable GPIO pins
"""
mask = (1 << ft232h_port_width) - 1
if self._ft232h_mode == 'I2C':
return mask & ~self._i2c_mask
elif self._ft232h_mode == 'SPI':
return mask & ~self._spi_mask
else:
return mask
@property
def _direction(self) -> int:
"""Provides the FTDI pin direction.
A :obj:`True` bit represents an output pin, a :obj:`False` bit an input pin.
Returns:
Bitfield of pins direction.
"""
if self._ft232h_mode == 'I2C':
return self._i2c_dir | self._gpio_dir
elif self._ft232h_mode == 'SPI':
no_cs_mask = 0xFFFF - (self._cs_bit if self.no_cs else 0)
return self._spi_dir | self._gpio_dir & no_cs_mask
else:
return self._gpio_dir
def _read_gpio_raw(self) -> int:
"""Sends the MPSSE commands for reading all the FT232H pins, and returns the
bitmap of read values. Values are determined using 3.3V logic.
Returns:
Bitmap of pins values
"""
cmd = bytes([ft232h_cmds['get_bits_low'],
ft232h_cmds['get_bits_high'],
ft232h_cmds['send_immediate']])
fmt = '<H'
self._write_data(cmd)
size = calcsize(fmt)
data = self._read_data_bytes(size, 8)
if len(data) != size:
raise IOError('Cannot read GPIO')
value, = unpack(fmt, data)
return value
[docs] def get_gpio(self, gpio_str: str) -> int:
"""Reads the 3.3V-logic voltage value of the specified pin.
Args:
gpio_str (:obj:`str`): Name of the GPIO to be read
Returns:
3.3V-logic value corresponding to the input voltage
"""
if gpio_str not in ft232h_pin_nr:
raise ValueError("gpio_id should be in {}".format(
list(ft232h_pin_nr.values())))
gpio_bit = ft232h_pin_nr[gpio_str]
if not self._gpio_all_pins & gpio_bit:
raise ValueError("Cannot use pin {} as a GPIO".format(gpio_str))
# Changing the _direction and _gpio_dir bitfields
if self._direction & gpio_bit:
self._gpio_dir &= 0xFFFF - gpio_bit
return self._read_gpio_raw() & gpio_bit
[docs] def set_gpio(self, gpio_str: str, value: int) -> None:
"""Sets the specified GPIO as an output and sets its output value.
Args:
gpio_str (:obj:`str`): Name of the GPIO to be set
value (:obj:`int`): 1 for setting the GPIO high, 0 for setting it low
"""
if value not in [0, 1]:
raise ValueError("value should be either 0 or 1")
if gpio_str not in ft232h_pin_nr:
raise ValueError("gpio_id should be in {}".format(
list(ft232h_pin_nr.values())))
gpio_bit = ft232h_pin_nr[gpio_str]
if not self._gpio_all_pins & gpio_bit:
raise ValueError("Cannot use pin {} as a GPIO".format(gpio_str))
# Changing the _direction and _gpio_dir bitfields
if not (self._direction & gpio_bit):
self._gpio_dir |= gpio_bit
data = self._read_gpio_raw()
if value == 1:
data |= gpio_bit
else:
data &= 0xFFFF - gpio_bit
low_data = data & 0xFF
low_dir = self._direction & 0xFF
high_data = (data >> 8) & 0xFF
high_dir = (self._direction >> 8) & 0xFF
cmd = bytes([ft232h_cmds['set_bits_low'], low_data, low_dir,
ft232h_cmds['set_bits_high'], high_data, high_dir])
self._write_data(cmd)
self._gpio_low = low_data & self._gpio_all_pins
self._gpio_high = high_data & self._gpio_all_pins
[docs] def close(self) -> None:
"""Closes the FTDI interface/port."""
if self._usb_dev:
if bool(self._usb_dev._ctx.handle):
try:
self._set_bitmode(0, ft232h.BitMode.RESET)
util.release_interface(self._usb_dev, self._index - 1)
except (IOError, ValueError, USBError):
pass
try:
self._usb_dev.attach_kernel_driver(self._index - 1)
except (NotImplementedError, USBError):
pass
util.dispose_resources(self._usb_dev)
self._usb_dev = None
[docs]class ft232h_server:
"""A class for controlling FTDI's USB to Serial FT232H.
This class is very similar to the :class:`ft232h` except it doesn't
directly instantiate the USB device nor send commands to it directly. Instead
the commands are sent to a USB server managing communication with the
different FT232H devices.
Communication in SPI and I2C are implemented, along with GPIO control. The
name of the methods for SPI and I2C communication are those of :mod:`smbus`
and :mod:`spidev` libraries, in order to facilitate the use and the
integration in a multi-backend environment. This class also allows to write a
USB serial number in the EEPROM, as there's no default serial number on the
chip.
Note:
The FT232H does not support clock stretching and this may cause bugs with
some I2C devices. Lowering the ``i2c_speed`` may solve the problem.
Important:
If using Adafruit's board, its `I2C Mode` switch should of course be set to
the correct value according to the chosen mode.
Important:
**Only for Linux users:** In order to drive the FT232H, the appropriate
udev rule should be set. This can be done using the `udev_rule_setter`
utility in ``crappy``'s `util` folder. It is also possible to add it
manually by running:
::
$ echo "SUBSYSTEM==\\"usb\\", ATTR{idVendor}==\\"0403\\", \
MODE=\\"0666\\\"" | sudo tee ftdi.rules > /dev/null 2>&1
in a shell opened in ``/etc/udev/rules.d``.
Important:
For controlling several FT232H from the same computer, it is first necessary
to set their USB serial numbers. Otherwise an error will be raised. This can
be done using the crappy utility ``Set_ft232h_serial_nr.py``.
"""
[docs] class BitMode(IntEnum):
"""Commands for changing the bit mode."""
RESET = 0x00 # switch off alternative mode (default to UART)
BITBANG = 0x01 # classical asynchronous bitbang mode
MPSSE = 0x02 # MPSSE mode, available on 2232x chips
SYNCBB = 0x04 # synchronous bitbang mode
MCU = 0x08 # MCU Host Bus Emulation mode,
OPTO = 0x10 # Fast Opto-Isolated Serial Interface Mode
CBUS = 0x20 # Bitbang on CBUS pins of R-type chips
SYNCFF = 0x40 # Single Channel Synchronous FIFO mode
[docs] def __init__(self,
mode: str,
block_number: int,
queue: Queue,
namespace: Namespace,
command_event: Event,
answer_event: Event,
next_block: Event,
done_event: Event,
serial_nr: str = None,
i2c_speed: float = 100E3,
spi_turbo: bool = False) -> None:
"""Checks the arguments validity, initializes the device and sets the locks.
Args:
mode (:obj:`str`): The communication mode, can be :
::
'SPI', 'I2C', 'GPIO_only', 'Write_serial_nr'
GPIOs can be driven in any mode, but faster speeds are achievable in
`GPIO_only` mode.
block_number (:obj:`int`): The blocks number that was assigned to this
instance of the class at the first contact with the USB server.
queue (:obj:`multiprocessing.Queue`): The queue in which the class
will put its block number so that the USB server knows it is requesting
control.
namespace (:obj:`multiprocessing.managers.Namespace`): The Namespace
object used by the USB server for receiving commands ans sending
answers.
command_event (:obj:`multiprocessing.Event`): An event object used by the
USB server to know when a new command was written by a block.
answer_event (:obj:`multiprocessing.Event`): An event object used by this
class to know when the USB server sent back an answer.
next_block (:obj:`multiprocessing.Event`): An event object, set by the USB
server to tell the blocks waiting for the control that now is maybe
their chance.
done_event (:obj:`multiprocessing.Event`): An event object set by the
block currently in control of the server to tell it that it is done
sending commands.
serial_nr (:obj:`str`, optional): The serial number of the FT232H to
drive. In `Write_serial_nr` mode, the serial number to be written.
i2c_speed (:obj:`str`, optional): In I2C mode, the I2C bus clock frequency
in Hz. Available values are :
::
100E3, 400E3, 1E6
or any value between `10kHz` and `100kHz`. Lowering below the default
value may solve I2C clock stretching issues on some devices.
spi_turbo (:obj:`str`, optional): Increases the achievable bus speed, but
may not work with some devices.
Note:
- **CS pin**:
The CS pin for selecting SPI devices is always `D3`. This pin is
reserved and cannot be used as a GPIO. If you want to drive the CS line
manually, it is possible not to drive the CS pin by setting the SPI
parameter :attr:`no_cs` to :obj:`True` and to drive the CS line from a
GPIO instead.
- ``mode``:
It is not possible to simultaneously control slaves over SPI and I2C,
due to different hardware requirements for the two protocols. Trying to
do so will most likely raise an error or lead to inconsistent behavior.
"""
if mode not in ft232h_modes:
raise ValueError("mode should be in {}".format(ft232h_modes))
self._ft232h_mode = mode
if mode == 'Write_serial_nr' and serial_nr is None:
raise ValueError("Cannot set serial number if it is not specified !")
if i2c_speed not in ft232h_i2c_speed:
try:
if not 10E3 <= i2c_speed < 100E3:
raise ValueError("i2c_speed should be in {} or between 10E3 and 100E3"
.format(list(ft232h_i2c_speed.values())))
except TypeError:
raise TypeError("i2c_speed should be a float or an int !")
self._gpio_low = 0
self._gpio_high = 0
self._gpio_dir = 0
self._retry_count = 8
self._usb_write_timeout = 5000
self._usb_read_timeout = 5000
self._turbo = spi_turbo
self._i2c_speed = i2c_speed
self._block_number = block_number
self._queue = queue
self._namespace = namespace
self._command_event = command_event
self._answer_event = answer_event
self._next_block = next_block
self._done_event = done_event
self._initialize()
if mode == 'Write_serial_nr':
self._set_serial_number(serial_nr)
self.close()
def _send_server(self, command: Union[list, str]) -> Any:
"""Method for sending commands and receiving answers from the server
managing the FT232H devices.
Args:
command (:obj:`str` or :obj:`list`): The command to send to the server.
Returns:
The answer from the server.
"""
# The timestamp of the last interaction with the server is constantly being
# saved because the multiprocessing objects timeouts are buggy
t = time()
while True:
try:
# Communication with the server is allowed only if the block is the one
# currently in control or if a next_block event is set
if self._namespace.current_block == self._block_number or \
self._next_block.wait(timeout=5):
if self._done_event.is_set():
# The previous block is done controlling the server but the server
# hasn't chosen the next block yet
continue
# Even if the next_block event is set, only the chosen block is
# is allowed to communicate
if self._namespace.current_block == self._block_number:
# The other blocks will have to wait
self._next_block.clear()
# Sending the command
setattr(self._namespace, 'command' + str(self._block_number),
command)
t = time()
# Telling that a command was sent
self._command_event.set()
else:
continue
else:
# Sometimes the wait method doesn't wait for the given timeout...
if self._next_block.wait(timeout=5):
continue
# Sometimes the timeout check fails twice
elif time() - t < 2:
continue
raise TimeoutError("The server took too long to choose block",
(self._block_number,
self._namespace.current_block))
# Retrieving the answer only if the answer_event is set
if self._answer_event.wait(timeout=5):
ret = getattr(self._namespace, 'answer' + str(self._block_number))
t = time()
# After a CTRL+C or SIGINT event, some of the namespace attributes
# may be buggy so switching to an "emergency" attribute for receiving
# the answers
if ret is None:
ret = getattr(self._namespace,
'answer' + str(self._block_number) + "'")
if ret is None:
continue
self._answer_event.clear()
# The answer may be an error that should be raised by a block rather
# than by the server
if isinstance(ret, Exception):
raise ret
# 'ok' is a special answer only received when the block wants to
# release control
elif ret == 'ok':
self._done_event.set()
else:
# Again the timeouts are sometimes buggy
if self._answer_event.wait(timeout=5):
continue
elif time() - t < 2:
continue
raise TimeoutError("The server took too long to reply",
self._block_number, self._namespace.current_block)
return ret
except KeyboardInterrupt:
# In case of a CTRL+C or SIGINT event, the block in control simply
# resets every event and sends again the command
if self._namespace.current_block == self._block_number:
self._command_event.clear()
self._answer_event.clear()
continue
# If the server is down, exiting
except (BrokenPipeError, ConnectionResetError):
break
def _initialize(self) -> None:
"""Initializing the FT232H according to the chosen mode.
The main differences are for the choice of the clock frequency and
parameters.
"""
self._queue.put_nowait(self._block_number)
# FT232H properties
fifo_sizes = (1024, 1024)
latency = 16
# I2C properties
if self._ft232h_mode == 'I2C':
timings = ft232h_i2c_speed[self._i2c_speed if self._i2c_speed in
ft232h_i2c_speed else 100E3]
frequency = self._i2c_speed
self._ck_hd_sta = self._compute_delay_cycles(timings.t_hd_sta)
self._ck_su_sto = self._compute_delay_cycles(timings.t_su_sto)
ck_su_sta = self._compute_delay_cycles(timings.t_su_sta)
ck_buf = self._compute_delay_cycles(timings.t_buf)
self._ck_idle = max(ck_su_sta, ck_buf)
self._ck_delay = ck_buf
self._i2c_mask = ft232h_pins['SCL'] | ft232h_pins['SDAO'] | \
ft232h_pins['SDAI']
self._i2c_dir = ft232h_pins['SCL'] | ft232h_pins['SDAO']
# SPI properties
elif self._ft232h_mode == 'SPI':
frequency = 400E3
self._bits_per_word = 8
self._cshigh = False
self._no_cs = False
self._loop = False
self._lsbfirst = False
self._max_speed_hz = 400E3
self._mode = 0
self._threewire = False
self._spi_param_changed = True
self._cs_bit = ft232h_pins['CS']
self._spi_dir = self._cs_bit | ft232h_pins['SCK'] | ft232h_pins['DO']
self._spi_mask = self._cs_bit | ft232h_pins['SCK'] | \
ft232h_pins['DO'] | ft232h_pins['DI']
else:
frequency = 400E3
# Configuring the USB device, interface and endpoints
try:
if self._send_server(['is_kernel_driver_active', 0]):
self._send_server(['detach_kernel_driver', 0])
self._send_server(['set_configuration'])
except USBError:
print("You may have to install the udev-rules for this USB device, "
"this can be done using the udev_rule_setter utility in the util "
"folder")
raise
self._index, self._in_ep, self._out_ep, self._max_packet_size = \
self._send_server(['get_active_configuration'])
# Invalidate data in the readbuffer
self._readoffset = 0
self._readbuffer = bytearray()
# Drain input buffer
self._purge_buffers()
# Shallow reset
if self._ctrl_transfer_out(ft232h_sio_req['reset'],
ft232h_sio_args['reset']):
raise IOError('Unable to reset FTDI device')
# Reset feature mode
self._set_bitmode(0, ft232h_server.BitMode.RESET)
# Set latency timer
self._set_latency_timer(latency)
# Set chunk size and invalidate all remaining data
self._writebuffer_chunksize = fifo_sizes[0]
self._readoffset = 0
self._readbuffer = bytearray()
self._readbuffer_chunksize = min(fifo_sizes[0], fifo_sizes[1],
self._max_packet_size)
# Reset feature mode
self._set_bitmode(0, ft232h_server.BitMode.RESET)
# Drain buffers
self._purge_buffers()
# Disable event and error characters
if self._ctrl_transfer_out(ft232h_sio_req['set_event_char'], 0):
raise IOError('Unable to set event char')
if self._ctrl_transfer_out(ft232h_sio_req['set_error_char'], 0):
raise IOError('Unable to set error char')
# Enable MPSSE mode
if self._ft232h_mode == 'GPIO_only':
self._set_bitmode(0xFF, ft232h_server.BitMode.BITBANG)
else:
self._set_bitmode(self._direction, ft232h_server.BitMode.MPSSE)
# Configure clock
if self._ft232h_mode == 'I2C':
# Note that bus frequency may differ from clock frequency, when
# 3-phase clock is enabled
self._set_frequency(3 * frequency / 2)
else:
self._set_frequency(frequency)
# Configure pins
if self._ft232h_mode == 'I2C':
cmd = bytearray(self._idle)
cmd.extend((ft232h_cmds['set_bits_high'], 0, 0))
self._write_data(cmd)
elif self._ft232h_mode == 'SPI':
cmd = bytearray((ft232h_cmds['set_bits_low'],
self._cs_bit & 0xFF,
self._direction & 0xFF))
cmd.extend((ft232h_cmds['set_bits_high'],
(self._cs_bit >> 8) & 0xFF,
(self._direction >> 8) & 0xFF))
self._write_data(cmd)
else:
cmd = bytearray((ft232h_cmds['set_bits_low'], 0, 0))
cmd.extend((ft232h_cmds['set_bits_high'], 0, 0))
self._write_data(cmd)
# Disable loopback
self._write_data(bytearray((ft232h_cmds['loopback_end'],)))
# Validate MPSSE
bytes_ = bytes(self._read_data_bytes(2))
if (len(bytes_) >= 2) and (bytes_[0] == '\xfa'):
raise IOError("Invalid command @ %d" % bytes_[1])
# I2C-specific settings
if self._ft232h_mode == 'I2C':
self._tx_size, self._rx_size = fifo_sizes
# Enable 3-phase clock
self._write_data(bytearray([True and
ft232h_cmds['enable_clk_3phase'] or
ft232h_cmds['disable_clk_3phase']]))
# Enable drivezero mode
self._write_data(bytearray([ft232h_cmds['drive_zero'],
self._i2c_mask & 0xFF,
(self._i2c_mask >> 8) & 0xFF]))
# Disable adaptative clock
self._write_data(bytearray([False and
ft232h_cmds['enable_clk_adaptative'] or
ft232h_cmds['disable_clk_adaptative']]))
self._send_server('stop')
@staticmethod
def _compute_delay_cycles(value: float) -> int:
"""Approximates the number of clock cycles over a given delay.
Args:
value (:obj:`float`): delay (in seconds)
Returns:
Number of clock cycles
"""
bit_delay = ft232h_mpsse_bit_delay
return max(1, int((value + bit_delay) / bit_delay))
def _set_latency_timer(self, latency: int) -> None:
"""Sets the latency timer.
Sets the latency timer, i.e. the delay the chip waits before sending the
data stored in the buffer to the host. Not applicable when a send
immediate command is issued, in which case the buffered data is returned
immediately.
Args:
latency (:obj:`int`): latency (in milliseconds)
"""
if not ft232h_latency['min'] <= latency <= ft232h_latency['max']:
raise ValueError("Latency out of range")
if self._ctrl_transfer_out(ft232h_sio_req['set_latency_timer'], latency):
raise IOError('Unable to set latency timer')
def _set_frequency(self, frequency: float) -> float:
"""Sets the bus frequency.
Sets the FT232H clock divisor value, according to the desired bus
frequency. The actual bus frequency is then as close as possible to the
desired value, but may still be slightly different.
Args:
frequency (:obj:`float`): Desired bus frequency (in Hz)
Returns:
Actual bus frequency
"""
# Calculate base speed clock divider
divcode = ft232h_cmds['enable_clk_div5']
divisor = int((ft232h_clock['base'] + frequency / 2) / frequency) - 1
divisor = max(0, min(0xFFFF, divisor))
actual_freq = ft232h_clock['base'] / (divisor + 1)
error = (actual_freq / frequency) - 1
# Calculate high speed clock divider
divisor_hs = int((ft232h_clock['high'] + frequency / 2) / frequency) - 1
divisor_hs = max(0, min(0xFFFF, divisor_hs))
actual_freq_hs = ft232h_clock['high'] / (divisor_hs + 1)
error_hs = (actual_freq_hs / frequency) - 1
# Enable if closer to desired frequency
# =====================================================================
if abs(error_hs) <= abs(error):
divcode = ft232h_cmds['disable_clk_div5']
divisor = divisor_hs
actual_freq = actual_freq_hs
# FTDI expects little endian
cmd = bytearray((divcode,))
cmd.extend((ft232h_cmds['set_tck_divisor'], divisor & 0xff,
(divisor >> 8) & 0xff))
cmd.extend((ft232h_cmds['send_immediate'],))
self._write_data(cmd)
# validate MPSSE
bytes_ = bytes(self._read_data_bytes(2))
if (len(bytes_) >= 2) and (bytes_[0] == '\xfa'):
raise IOError("Invalid command @ %d" % bytes_[1])
# Drain input buffer
self._purge_rx_buffer()
return actual_freq
def _set_bitmode(self, bitmask: int, mode: BitMode) -> None:
"""Sets the bitbang mode.
Args:
bitmask (:obj:`int`): Mask for choosing the driven GPIOs.
mode (:class:`BitMode`): Bitbang mode to be set.
"""
mask = sum(ft232h_server.BitMode)
value = (bitmask & 0xff) | ((mode.value & mask) << 8)
if self._ctrl_transfer_out(ft232h_sio_req['set_bitmode'], value):
raise IOError('Unable to set bitmode')
def _purge_buffers(self) -> None:
"""Clears the buffers on the chip and the internal read buffer."""
self._purge_rx_buffer()
self._purge_tx_buffer()
def _purge_rx_buffer(self) -> None:
"""Clears the USB receive buffer on the chip (host-to-ftdi) and the
internal read buffer."""
if self._ctrl_transfer_out(ft232h_sio_req['reset'],
ft232h_sio_args['purge_RX']):
raise IOError('Unable to flush RX buffer')
# Invalidate data in the readbuffer
self._readoffset = 0
self._readbuffer = bytearray()
def _purge_tx_buffer(self) -> None:
"""Clears the USB transmit buffer on the chip (ftdi-to-host)."""
if self._ctrl_transfer_out(ft232h_sio_req['reset'],
ft232h_sio_args['purge_TX']):
raise IOError('Unable to flush TX buffer')
def _ctrl_transfer_out(self,
reqtype: int,
value: int,
data: bytes = b'') -> int:
"""Sends a control message to the device.
Args:
reqtype (:obj:`int`): bmRequest
value (:obj:`int`): wValue
data (:obj:`bytes`): payload
Returns:
Number of bytes actually written
"""
try:
return self._send_server(['ctrl_transfer', Ftdi_req_out, reqtype, value,
self._index, bytearray(data),
self._usb_write_timeout])
except USBError as ex:
raise IOError('UsbError: %s' % str(ex))
def _set_serial_number(self, serial_number: str) -> None:
"""(Over)Writes the serial number.
Writes the desired serial number to the EEPROM. It is then accessible to
USB commands as a string descriptor. Also sets the manufacturer and
product string descriptors.
Args:
serial_number (:obj:`str`): Serial number to be written in the EEPROM
"""
self._queue.put_nowait(self._block_number)
if not isinstance(serial_number, str):
serial_number = str(serial_number)
if any(char in serial_number for char in ':/'):
raise ValueError("Invalid character : or / in serial number")
# Reading current eeprom
word_count = round(ft232h_eeprom_size / 2)
word_addr = 0
data = bytearray()
while word_count:
try:
buf = self._send_server(['ctrl_transfer', Ftdi_req_in,
ft232h_sio_req['read_eeprom'], 0, word_addr, 2,
self._usb_read_timeout])
except USBError as exc:
raise IOError('UsbError: %s' % exc) from exc
if not buf:
raise IOError('EEPROM read error @ %d' % (word_addr << 1))
data.extend(buf)
word_count -= 1
word_addr += 1
new_eeprom = data[0:ft232h_eeprom_size]
# Setting the has_serial flag to True
new_eeprom[ft232h_eeprom['has_serial_pos']] |= 1 << 3
# Changing the string descriptors and the descriptors index
str_descriptors = {'manufacturer': 'FTDI',
'product': 'FT232H',
'serial': serial_number}
stream = bytearray()
str_pos = ft232h_eeprom['str_position']
tbl_pos = ft232h_eeprom['str_table']
data_pos = str_pos
for name in str_descriptors:
new_str = str_descriptors[name].encode('utf-16le')
length = len(new_str) + 2
stream.append(length)
stream.append(util.DESC_TYPE_STRING) # string descriptor
stream.extend(new_str)
new_eeprom[tbl_pos] = data_pos
tbl_pos += 1
new_eeprom[tbl_pos] = length
tbl_pos += 1
data_pos += length
new_eeprom[str_pos:str_pos + len(stream)] = stream
# Filling the remaining space with zeros
crc_pos = len(new_eeprom)
rem = crc_pos - (str_pos + len(stream))
new_eeprom[str_pos + len(stream):crc_pos] = bytes(rem)
# Checking the eeprom length
if len(new_eeprom) != ft232h_eeprom_size:
raise ValueError("Eeprom_size not matching, serial number may be "
"too long, eeprom not written")
# Calculating the new checksum and modifying the corresponding bytes
checksum = 0xAAAA
for idx in range(0, len(new_eeprom[:-2]), 2):
v = ((new_eeprom[:-2][idx + 1] << 8) + new_eeprom[:-2][idx]) & 0xFFFF
checksum = v ^ checksum
checksum = ((checksum << 1) & 0xFFFF) | ((checksum >> 15) & 0xFFFF)
new_eeprom[-2] = checksum & 0xFF
new_eeprom[-1] = checksum >> 8
# Updating the eeprom
addr = 0
for word in unpack('<%dH' % (len(new_eeprom) // 2), new_eeprom):
out = self._send_server(['ctrl_transfer', Ftdi_req_out,
ft232h_sio_req['write_eeprom'], word, addr >> 1,
b'', self._usb_write_timeout])
if out:
raise IOError('EEPROM Write Error @ %d' % addr)
addr += 2
self._send_server('stop')
def _write_data(self, data: Union[bytearray, bytes]) -> int:
"""Writes data to the FT232H.
Writes the sequence of MPSSE commands and data to the FTDI port. Data
buffer is split into chunk-sized blocks before being sent over the USB bus.
Args:
data: The byte stream to send to the FTDI interface
Returns:
Count of written bytes
"""
offset = 0
size = len(data)
try:
while offset < size:
write_size = self._writebuffer_chunksize
if offset + write_size > size:
write_size = size - offset
try:
length = self._send_server(['write', self._in_ep,
data[offset:offset + write_size],
self._usb_write_timeout])
except USBError:
raise
if length <= 0:
raise USBError("Usb bulk write error")
offset += length
return offset
except USBError:
print("An error occurred while writing to USB")
raise
def _read_data_bytes(self,
size: int,
attempt: int = 2,
request_gen: Callable = None) -> bytes:
"""Reads data from the FT232H.
Reads data from the FTDI interface. The data buffer is rebuilt from
chunk-sized blocks received over the USB bus. The FTDI device always sends
internal status bytes, which are stripped out as not part of the data
payload.
Args:
size (:obj:`int`): The number of bytes to receive from the device
attempt (:obj:`int`): Attempt cycle count
request_gen: A callable that takes the number of bytes read and expects a
bytes buffer to send back to the remote device. This is only useful to
perform optimized/continuous transfer from a slave device.
Returns:
Payload bytes
"""
# Packet size sanity check
if not self._max_packet_size:
raise ValueError("max_packet_size is bogus")
packet_size = self._max_packet_size
length = 1 # initial condition to enter the usb_read loop
data = bytearray()
# everything we want is still in the cache?
if size <= len(self._readbuffer) - self._readoffset:
data = self._readbuffer[self._readoffset:self._readoffset + size]
self._readoffset += size
return data
# something still in the cache, but not enough to satisfy 'size'?
if len(self._readbuffer) - self._readoffset != 0:
data = self._readbuffer[self._readoffset:]
# end of readbuffer reached
self._readoffset = len(self._readbuffer)
# read from USB, filling in the local cache as it is empty
retry = attempt
req_size = size
try:
while (len(data) < size) and (length > 0):
while True:
try:
tempbuf = self._send_server(['read', self._out_ep,
self._readbuffer_chunksize,
self._usb_read_timeout])
except USBError:
raise
retry -= 1
length = len(tempbuf)
# the received buffer contains at least one useful databyte
# (first 2 bytes in each packet represent the current modem
# status)
if length >= 2:
if tempbuf[1] & ft232h_tx_empty_bits:
if request_gen:
req_size -= length - 2
if req_size > 0:
cmd = request_gen(req_size)
if cmd:
self._write_data(cmd)
if length > 2:
retry = attempt
# skip the status bytes
chunks = (length + packet_size - 1) // packet_size
count = packet_size - 2
self._readbuffer = bytearray()
self._readoffset = 0
srcoff = 2
for _ in range(chunks):
self._readbuffer += tempbuf[srcoff:srcoff + count]
srcoff += packet_size
length = len(self._readbuffer)
break
# received buffer only contains the modem status bytes
# no data received, may be late, try again
if retry > 0:
continue
# no actual data
self._readbuffer = bytearray()
self._readoffset = 0
# no more data to read?
return data
if length > 0:
# data still fits in buf?
if (len(data) + length) <= size:
data += self._readbuffer[self._readoffset:
self._readoffset + length]
self._readoffset += length
# did we read exactly the right amount of bytes?
if len(data) == size:
return data
else:
# partial copy, not enough bytes in the local cache to
# fulfill the request
part_size = min(size - len(data),
len(self._readbuffer) - self._readoffset)
if part_size < 0:
raise ValueError("Internal Error")
data += self._readbuffer[self._readoffset:
self._readoffset + part_size]
self._readoffset += part_size
return data
except USBError:
print("An error occurred while writing to USB")
raise
# never reached
raise ValueError("Internal error")
@property
def _clk_hi_data_lo(self) -> tuple:
"""Returns the MPSSE command for driving CLK line high and SDA line low,
while preserving the GPIO outputs."""
return (ft232h_cmds['set_bits_low'],
ft232h_pins['SCL'] | self._gpio_low,
self._i2c_dir | (self._gpio_dir & 0xFF))
@property
def _clk_lo_data_input(self) -> tuple:
"""Returns the MPSSE command for driving CLK line low and listening to SDA
line, while preserving the GPIO outputs."""
return (ft232h_cmds['set_bits_low'],
self._gpio_low,
ft232h_pins['SCL'] | (self._gpio_dir & 0xFF))
@property
def _clk_lo_data_hi(self) -> tuple:
"""Returns the MPSSE command for driving CLK line low and SDA line high,
while preserving the GPIO outputs."""
return (ft232h_cmds['set_bits_low'],
ft232h_pins['SDAO'] | self._gpio_low,
self._i2c_dir | (self._gpio_dir & 0xFF))
@property
def _clk_lo_data_lo(self) -> tuple:
"""Returns the MPSSE command for driving CLK line low and SDA line low,
while preserving the GPIO outputs."""
return (ft232h_cmds['set_bits_low'],
self._gpio_low,
self._i2c_dir | (self._gpio_dir & 0xFF))
@property
def _idle(self) -> tuple:
"""Returns the MPSSE command for driving CLK line high and SDA line high,
while preserving the GPIO outputs."""
return (ft232h_cmds['set_bits_low'],
self._i2c_dir | self._gpio_low,
self._i2c_dir | (self._gpio_dir & 0xFF))
@property
def _start(self) -> tuple:
"""Returns the MPSSE command for issuing and I2C start condition."""
return self._clk_hi_data_lo * self._ck_hd_sta + \
self._clk_lo_data_lo * self._ck_hd_sta
@property
def _stop(self) -> tuple:
"""Returns the MPSSE command for issuing and I2C stop condition."""
return self._clk_lo_data_hi * self._ck_hd_sta + \
self._clk_lo_data_lo * self._ck_hd_sta + \
self._clk_hi_data_lo * self._ck_su_sto + \
self._idle * self._ck_idle
def _do_prolog(self, i2caddress: int) -> None:
"""Sends the MPSSE commands for starting an I2C transaction.
Args:
i2caddress (:obj:`int`): I2C address of the slave
"""
if i2caddress is None:
return
cmd = bytearray(self._idle * self._ck_delay)
cmd.extend(self._start)
cmd.extend((ft232h_cmds['write_bytes_NVE_MSB'], 0, 0))
cmd.append(i2caddress)
try:
self._send_check_ack(cmd)
except IOError:
raise
def _do_write(self, out: list) -> None:
"""Sends the MPSSE commands for writing bytes to an I2C slave.
Args:
out (:obj:`list`): List of bytes to write
"""
if not isinstance(out, bytearray):
out = bytearray(out)
if not out:
return
for byte in out:
cmd = bytearray((ft232h_cmds['write_bytes_NVE_MSB'], 0, 0))
cmd.append(byte)
self._send_check_ack(cmd)
def _do_read(self, readlen: int) -> bytearray:
"""
Sends the MPSSE commands for reading bytes from an I2C slave, and then
returns these bytes.
Args:
readlen: Number of bytes to read
Returns: Read bytes as a bytearray
"""
if not readlen:
# force a real read request on device, but discard any result
cmd = bytearray()
cmd.extend((ft232h_cmds['send_immediate'],))
self._write_data(cmd)
self._read_data_bytes(0, 8)
return bytearray()
ack = (ft232h_cmds['write_bits_NVE_MSB'], 0, 0)
nack = (ft232h_cmds['write_bits_NVE_MSB'], 0, 0xFF)
read_not_last = ((ft232h_cmds['read_bytes_PVE_MSB'], 0, 0) + ack +
self._clk_lo_data_hi * self._ck_delay)
read_last = ((ft232h_cmds['read_bytes_PVE_MSB'], 0, 0) + nack +
self._clk_lo_data_hi * self._ck_delay)
# maximum RX size to fit in FTDI FIFO, minus 2 status bytes
chunk_size = self._rx_size - 2
cmd_size = len(read_last)
# limit RX chunk size to the count of I2C packable commands in the FTDI
# TX FIFO (minus one byte for the last 'send immediate' command)
tx_count = (self._tx_size - 1) // cmd_size
chunk_size = min(tx_count, chunk_size)
chunks = []
rem = readlen
if rem > chunk_size:
chunk_size //= 2
cmd_chunk = bytearray()
cmd_chunk.extend(read_not_last * chunk_size)
cmd_chunk.extend((ft232h_cmds['send_immediate'],))
def _write_command_gen(length: int) -> Union[bytearray, bytes]:
if length <= 0:
# no more data
return b''
if length <= chunk_size:
cmd_ = bytearray()
cmd_.extend(read_not_last * (length - 1))
cmd_.extend(read_last)
cmd_.extend((ft232h_cmds['send_immediate'],))
return cmd_
return cmd_chunk
while rem:
buf = self._read_data_bytes(rem, 80, _write_command_gen)
chunks.append(buf)
rem -= len(buf)
else:
cmd = bytearray()
cmd.extend(read_not_last * (rem - 1))
cmd.extend(read_last)
cmd.extend((ft232h_cmds['send_immediate'],))
size = rem
self._write_data(cmd)
buf = self._read_data_bytes(size, 8)
chunks.append(buf)
return bytearray(b''.join(chunks))
def _send_check_ack(self, cmd: bytearray) -> None:
"""Actually sends the MPSSE commands generated by :meth:`_do_prolog` and
:meth:`_do_write` methods, and checks whether the slave ACKs it.
Args:
cmd (:obj:`bytearray`): The MPSSE commands to send
"""
# SCL low, SDA high-Z
cmd.extend(self._clk_lo_data_hi)
# read SDA (ack from slave)
cmd.extend((ft232h_cmds['read_bits_PVE_MSB'], 0))
cmd.extend((ft232h_cmds['send_immediate'],))
self._write_data(cmd)
ack = self._read_data_bytes(1, 8)
if not ack:
raise IOError('No answer from FTDI')
if ack[0] & 0x01:
raise IOError('NACK from slave')
def _write_i2c(self, address: int, out: list) -> None:
"""Writes bytes to an I2C slave.
Args:
address (:obj:`int`): I2C address of the slave
out (:obj:`list`): List of bytes to send
"""
i2caddress = (address << 1) & 0xFF
retries = self._retry_count
while True:
try:
self._do_prolog(i2caddress)
self._do_write(out)
return
except IOError:
retries -= 1
if not retries:
raise
finally:
self._write_data(bytearray(self._stop))
def _exchange_i2c(self,
address: int,
out: list,
readlen: int = 0) -> bytearray:
"""Writes bytes to an I2C slave, and then reads a given number of bytes
from this same slave.
Args:
address (:obj:`int`): I2C address of the slave
out (:obj:`list`): List of bytes to send
readlen (:obj:`int`): Number of bytes to read
Returns:
Read bytes as a bytearray
"""
if readlen < 1:
raise IOError('Nothing to read')
if readlen > (ft232h_max_payload / 3 - 1):
raise IOError("Input payload is too large")
if address is None:
i2caddress = None
else:
i2caddress = (address << 1) & 0xFF
retries = self._retry_count
while True:
try:
self._do_prolog(i2caddress)
self._do_write(out)
self._do_prolog(i2caddress | 0x01)
data = self._do_read(readlen)
return data
except IOError:
retries -= 1
if not retries:
raise
finally:
self._write_data(bytearray(self._stop))
[docs] def write_byte(self, i2c_addr: int, value: int) -> None:
"""Writes a single byte to an I2C slave, in register 0.
Args:
i2c_addr (:obj:`int`): I2C address of the slave
value (:obj:`int`): The value to write
"""
self.write_i2c_block_data(i2c_addr=i2c_addr,
register=0x00,
data=[value & 0xFF])
[docs] def write_byte_data(self, i2c_addr: int, register: int, value: int) -> None:
"""Writes a single byte to an I2C slave, in the specified register.
Args:
i2c_addr (:obj:`int`): I2C address of the slave
register (:obj:`int`): Index of the register to be written
value (:obj:`int`): The value to write
"""
self.write_i2c_block_data(i2c_addr=i2c_addr,
register=register,
data=[value & 0xFF])
[docs] def write_word_data(self, i2c_addr: int, register: int, value: int) -> None:
"""Writes 2 bytes to an I2C slave from a single int value, starting at the
specified register.
Depending on the size of the registers, the next register may be written as
well.
Args:
i2c_addr (:obj:`int`): I2C address of the slave
register (:obj:`int`): Index of the first register to be written
value (:obj:`int`): The value to write
"""
self.write_i2c_block_data(i2c_addr=i2c_addr,
register=register,
data=[(value >> 8) & 0xFF, value & 0xFF])
[docs] def write_block_data(self, i2c_addr: int, register: int, data: list) -> None:
"""Actually calls :meth:`write_i2c_block_data`.
Args:
i2c_addr (:obj:`int`): I2C address of the slave
register (:obj:`int`): Index of the first register to be written
data (:obj:`list`): List of bytes to write
"""
self.write_i2c_block_data(i2c_addr=i2c_addr,
register=register,
data=data)
[docs] def write_i2c_block_data(self,
i2c_addr: int,
register: int,
data: list) -> None:
"""Writes bytes from a :obj:`list` to an I2C slave, starting at the
specified register.
Args:
i2c_addr (:obj:`int`): I2C address of the slave
register (:obj:`int`): Index of the first register to be written
data (:obj:`list`): List of bytes to write
"""
self._queue.put_nowait(self._block_number)
if self._ft232h_mode != 'I2C':
raise ValueError("Method only available in I2C mode")
if not 0 <= i2c_addr <= 127:
raise ValueError("Incorrect i2c address, should be between 0 and 127")
self._write_i2c(address=i2c_addr,
out=[register] + data)
self._send_server('stop')
[docs] def read_byte(self, i2c_addr: int) -> int:
"""Reads a single byte from an I2C slave, from the register `0`.
Args:
i2c_addr (:obj:`int`): I2C address of the slave
Returns:
Value of the read register
"""
try:
return self.read_i2c_block_data(i2c_addr=i2c_addr,
register=0x00,
length=1)[0]
except IndexError:
print("No data to read")
raise
[docs] def read_byte_data(self, i2c_addr: int, register: int) -> int:
"""Reads a single byte from an I2C slave, from the specified register.
Args:
i2c_addr (:obj:`int`): I2C address of the slave
register (:obj:`int`): Index of the register to be read
Returns:
Value of the read register
"""
try:
return self.read_i2c_block_data(i2c_addr=i2c_addr,
register=register,
length=1)[0]
except IndexError:
print("No data to read")
raise
[docs] def read_word_data(self, i2c_addr: int, register: int) -> int:
"""Reads 2 bytes from an I2C slave, starting at the specified register, and
returns them as one single value.
Args:
i2c_addr (:obj:`int`): I2C address of the slave
register (:obj:`int`): Index of the first register to be read
Returns:
Value of the read registers
"""
try:
ret = self.read_i2c_block_data(i2c_addr=i2c_addr,
register=register,
length=2)
return (ret[0] << 8) & ret[1]
except IndexError:
print("Not enough data to read")
raise
[docs] def read_i2c_block_data(self,
i2c_addr: int,
register: int,
length: int) -> list:
"""Reads a given number of bytes from an I2C slave, starting at the
specified register.
Args:
i2c_addr (:obj:`int`): I2C address of the slave
register (:obj:`int`): Index of the first register to be read
length (:obj:`int`): Number of bytes to read
Returns:
Values of read registers as a :obj:`list`
"""
self._queue.put_nowait(self._block_number)
if self._ft232h_mode != 'I2C':
raise ValueError("Method only available in I2C mode")
if not 0 <= i2c_addr <= 127:
raise ValueError("Incorrect i2c address, should be between 0 and 127")
if not length >= 0:
raise ValueError("length should be a positive integer")
if length == 0:
self._send_server('stop')
return []
ret = [byte for byte in self._exchange_i2c(address=i2c_addr,
out=[register],
readlen=length)]
self._send_server('stop')
return ret
@property
def bits_per_word(self) -> int:
"""Number of bits per SPI words.
Can only be set to 8.
"""
if self._ft232h_mode != 'SPI':
raise ValueError("Attribute only available in SPI mode")
return self._bits_per_word
@bits_per_word.setter
def bits_per_word(self, value: int) -> None:
if self._ft232h_mode != 'SPI':
raise ValueError("Attribute only available in SPI mode")
if not isinstance(value, int):
raise TypeError("bits_per_word should be an integer")
if value != 8:
raise ValueError("bits_per_word values other than 8 are not implemented")
self._bits_per_word = value
@property
def cshigh(self) -> bool:
"""If :obj:`True`, the polarity of the CS line is inverted."""
if self._ft232h_mode != 'SPI':
raise ValueError("Attribute only available in SPI mode")
return self._cshigh
@cshigh.setter
def cshigh(self, value: bool) -> None:
if self._ft232h_mode != 'SPI':
raise ValueError("Attribute only available in SPI mode")
if not isinstance(value, bool):
raise TypeError("cshigh should be either True or False")
self._spi_param_changed = True
self._cshigh = value
@property
def loop(self) -> bool:
"""If :obj:`True`, the loopback mode is enabled."""
if self._ft232h_mode != 'SPI':
raise ValueError("Attribute only available in SPI mode")
return self._loop
@loop.setter
def loop(self, value: bool) -> None:
self._queue.put_nowait(self._block_number)
if self._ft232h_mode != 'SPI':
raise ValueError("Attribute only available in SPI mode")
if not isinstance(value, bool):
raise TypeError("loop should be either True or False")
if value:
self._write_data(bytearray((ft232h_cmds['loopback_start'],)))
else:
self._write_data(bytearray((ft232h_cmds['loopback_end'],)))
self._loop = value
self._send_server('stop')
@property
def no_cs(self) -> bool:
"""If :obj:`True`, the CS line is not driven."""
if self._ft232h_mode != 'SPI':
raise ValueError("Attribute only available in SPI mode")
return self._no_cs
@no_cs.setter
def no_cs(self, value: bool) -> None:
if self._ft232h_mode != 'SPI':
raise ValueError("Attribute only available in SPI mode")
if not isinstance(value, bool):
raise TypeError("no_cs should be either True or False")
self._no_cs = value
@property
def lsbfirst(self) -> bool:
"""If :obj:`True`, data is sent and received LSB first."""
if self._ft232h_mode != 'SPI':
raise ValueError("Attribute only available in SPI mode")
return self._lsbfirst
@lsbfirst.setter
def lsbfirst(self, value: bool) -> None:
if self._ft232h_mode != 'SPI':
raise ValueError("Attribute only available in SPI mode")
if not isinstance(value, bool):
raise TypeError("lsbfirst should be either True or False")
self._lsbfirst = value
@property
def max_speed_hz(self) -> float:
"""The SPI bus clock frequency in Hz.
In SPI modes `1` and `3`, the actual bus clock frequency is 50% higher than
the input value because the FT232H is switched to 3-phase clock mode.
"""
if self._ft232h_mode != 'SPI':
raise ValueError("Attribute only available in SPI mode")
return self._max_speed_hz
@max_speed_hz.setter
def max_speed_hz(self, value: float) -> None:
self._queue.put_nowait(self._block_number)
if self._ft232h_mode != 'SPI':
raise ValueError("Attribute only available in SPI mode")
if self.mode in [1, 3]:
if not 3200 <= value <= 2 * ft232h_clock['high'] / 3:
raise ValueError("max_speed_hz should be between 3.2kHz and 20MHz in "
"spi modes 1 and 3")
else:
if not 4800 <= value <= ft232h_clock['high']:
raise ValueError("max_speed_hz should be between 4.8kHz and 30MHz in "
"spi modes 0 and 2")
self._spi_param_changed = True
if self.mode in [1, 3]:
self._set_frequency(3 * value / 2)
self._write_data(bytearray([True and
ft232h_cmds['enable_clk_3phase'] or
ft232h_cmds['disable_clk_3phase']]))
else:
self._set_frequency(value)
self._write_data(bytearray([False and
ft232h_cmds['enable_clk_3phase'] or
ft232h_cmds['disable_clk_3phase']]))
self._max_speed_hz = value
self._send_server('stop')
@property
def mode(self) -> int:
"""The SPI mode used for communicating with the slave.
When changing the SPI mode, the bus clock frequency may be reloaded.
"""
if self._ft232h_mode != 'SPI':
raise ValueError("Attribute only available in SPI mode")
return self._mode
@mode.setter
def mode(self, value: int) -> None:
if self._ft232h_mode != 'SPI':
raise ValueError("Attribute only available in SPI mode")
if value not in range(4):
raise ValueError("mode should be an integer between 0 and 3")
former_mode = self.mode
self._mode = value
self._spi_param_changed = True
if value % 2 != former_mode % 2:
self.max_speed_hz = self.max_speed_hz
@property
def threewire(self) -> bool:
"""If :obj:`True`, indicates that the MISO and MOSI lines are connected
together. Not currently implemented."""
if self._ft232h_mode != 'SPI':
raise ValueError("Attribute only available in SPI mode")
return self._threewire
@threewire.setter
def threewire(self, value: bool) -> None:
if self._ft232h_mode != 'SPI':
raise ValueError("Attribute only available in SPI mode")
if not isinstance(value, bool):
raise TypeError("threewire should be either True or False")
if value:
raise ValueError("threewire mode not implemented")
self._threewire = value
def _exchange_spi(self, readlen: int, out: list, start: bool,
stop: bool, duplex: bool) -> bytes:
"""Exchanges bytes with an SPI slave.
Can read and/or write data, in a sequential or simultaneous way. Also
manages the CS line.
Args:
readlen (:obj:`int`): Number of bytes to read. If 0, no reading is
performed.
out (:obj:`list`): List of bytes to write. If empty, no writing is
performed.
start (:obj:`bool`): If :obj:`False`, the CS line is not driven before
exchanging data, and remains in its previous state.
stop (:obj:`bool`): If :obj:`False`, the CS line is not driven after
exchanging data, and remains in its previous state.
duplex (:obj:`int`): If :obj:`True`, the data is read and written
simultaneously. If :obj:`False`, writes then reads in a sequential way.
Returns:
Read data as bytes
"""
if len(out) > ft232h_max_payload:
raise IOError("Output payload is too large")
if readlen > ft232h_max_payload:
raise IOError("Input payload is too large")
if not isinstance(out, bytearray):
out = bytearray(out)
# Re-building the _cs_prolog and _cs_epilog if an SPI parameter has been
# modified
if self._spi_param_changed:
cs_hold = 1 + int(1E6 / self.max_speed_hz)
self._cpol = self.mode & 0x2
cs_clock = 0xFFFF & ~((~self._cpol & ft232h_pins['SCK']) |
ft232h_pins['DO'] |
(self.cshigh and self._cs_bit))
cs_select = 0xFFFF & ~((~self._cpol & ft232h_pins['SCK']) |
ft232h_pins['DO'] |
((not self.cshigh) and self._cs_bit))
self._cs_prolog = [cs_clock, cs_select]
self._cs_epilog = [cs_select] + [cs_clock] * cs_hold
self._spi_param_changed = False
# Building the prolog MPSSE command
cmd = bytearray()
if start:
for ctrl in self._cs_prolog:
ctrl &= self._spi_mask
ctrl |= self._gpio_low
ctrl |= self._gpio_high << 8
cmd.extend((ft232h_cmds['set_bits_low'], ctrl & 0xFF,
self._direction & 0xFF))
# Building the epilog MPSSE command
epilog = bytearray()
for ctrl in self._cs_epilog:
ctrl &= self._spi_mask
ctrl |= self._gpio_low
ctrl |= self._gpio_high << 8
epilog.extend((ft232h_cmds['set_bits_low'], ctrl & 0xFF,
self._direction & 0xFF))
# Restore idle state
if not self.cshigh:
cs_high = [ft232h_cmds['set_bits_low'], self._cs_bit |
self._gpio_low & 0xFF,
self._direction & 0xFF]
else:
cs_high = [ft232h_cmds['set_bits_low'], self._gpio_low & 0xFF,
self._direction & 0xFF]
if not self._turbo:
cs_high.append(ft232h_cmds['send_immediate'])
epilog.extend(cs_high)
# Sequential communication
if not duplex:
# Write MPSSE commands
writelen = len(out)
if writelen:
if not self.lsbfirst:
wcmd = (ft232h_cmds['write_bytes_NVE_MSB'] if not self._cpol else
ft232h_cmds['write_bytes_PVE_MSB'])
else:
wcmd = (ft232h_cmds['write_bytes_NVE_LSB'] if not self._cpol else
ft232h_cmds['write_bytes_PVE_LSB'])
write_cmd = pack('<BH', wcmd, writelen - 1)
cmd.extend(write_cmd)
cmd.extend(out)
# Read MPSSE commands
if readlen:
if not self.lsbfirst:
rcmd = (ft232h_cmds['read_bytes_NVE_MSB'] if not self._cpol else
ft232h_cmds['read_bytes_PVE_MSB'])
else:
rcmd = (ft232h_cmds['read_bytes_NVE_LSB'] if not self._cpol else
ft232h_cmds['read_bytes_PVE_LSB'])
read_cmd = pack('<BH', rcmd, readlen - 1)
cmd.extend(read_cmd)
# ====================================================================
if self._turbo:
cmd.extend((ft232h_cmds['send_immediate'],))
if self._turbo:
if stop:
cmd.extend(epilog)
self._write_data(cmd)
else:
self._write_data(cmd)
if stop:
self._write_data(epilog)
# USB read cycle may occur before the FTDI device has actually
# sent the data, so try to read more than once if no data is
# actually received
data = self._read_data_bytes(readlen, 8)
# If nothing to read
else:
if writelen:
if self._turbo:
if stop:
cmd.extend(epilog)
self._write_data(cmd)
else:
self._write_data(cmd)
if stop:
self._write_data(epilog)
data = bytearray()
# Simultaneous communication
else:
if readlen > len(out):
tmp = bytearray(out)
tmp.extend([0] * (readlen - len(out)))
out = tmp
exlen = len(out)
if not self.lsbfirst:
wcmd = (ft232h_cmds['rw_bytes_PVE_NVE_MSB'] if not self._cpol else
ft232h_cmds['rw_bytes_NVE_PVE_MSB'])
else:
wcmd = (ft232h_cmds['rw_bytes_PVE_NVE_LSB'] if not self._cpol else
ft232h_cmds['rw_bytes_NVE_PVE_LSB'])
write_cmd = pack('<BH', wcmd, exlen - 1)
cmd.extend(write_cmd)
cmd.extend(out)
# ======================================================================
if self._turbo:
cmd.extend((ft232h_cmds['send_immediate'],))
if self._turbo:
if stop:
cmd.extend(epilog)
self._write_data(cmd)
else:
self._write_data(cmd)
if stop:
self._write_data(epilog)
# USB read cycle may occur before the FTDI device has actually
# sent the data, so try to read more than once if no data is
# actually received
data = self._read_data_bytes(exlen, 8)
return data
[docs] def readbytes(self, len: int, start: bool = True, stop: bool = True) -> list:
"""Reads the specified number of bytes from an SPI slave.
Args:
len (:obj:`int`): Number of bytes to read
start (:obj:`bool`): If :obj:`False`, the CS line is not driven before
reading data, and remains in its previous state.
stop (:obj:`bool`): If :obj:`False`, the CS line is not driven after
reading data, and remains in its previous state.
Returns:
List of read bytes
"""
self._queue.put_nowait(self._block_number)
if self._ft232h_mode != 'SPI':
raise ValueError("Method only available in SPI mode")
ret = [byte for byte in self._exchange_spi(readlen=len,
out=[],
start=start,
stop=stop,
duplex=False)]
self._send_server('stop')
return ret
[docs] def writebytes(self,
values: list,
start: bool = True,
stop: bool = True) -> None:
"""Write bytes from a list to an SPI slave.
Args:
values (:obj:`list`): List of bytes to write
start (:obj:`bool`): If :obj:`False`, the CS line is not driven before
reading data, and remains in its previous state.
stop (:obj:`bool`): If :obj:`False`, the CS line is not driven after
reading data, and remains in its previous state.
"""
self._queue.put_nowait(self._block_number)
if self._ft232h_mode != 'SPI':
raise ValueError("Method only available in SPI mode")
self._exchange_spi(readlen=0,
out=values,
start=start,
stop=stop,
duplex=False)
self._send_server('stop')
[docs] def writebytes2(self,
values: list,
start: bool = True,
stop: bool = True) -> None:
"""Actually calls the :meth:`writebytes` method with the same arguments."""
self.writebytes(values=values,
start=start,
stop=stop)
[docs] def xfer(self,
values: list,
speed: float = None,
delay: float = 0.0,
bits: int = 8,
start: bool = True,
stop: bool = True) -> list:
"""Simultaneously reads and write bytes to an SPI slave.
The number of bytes to read is equal to the number of bytes in the write
buffer.
Args:
values (:obj:`list`): List of bytes to write
speed (:obj:`float`): Sets the bus clock frequency before issuing the
command (in Hz)
delay (:obj:`float`): Not implemented, should be 0.0
bits (:obj:`int`): Not implemented, should be 8
start (:obj:`bool`): If :obj:`False`, the CS line is not driven before
reading data, and remains in its previous state.
stop (:obj:`bool`): If :obj:`False`, the CS line is not driven after
reading data, and remains in its previous state.
Returns:
List of read bytes
"""
self._queue.put_nowait(self._block_number)
if self._ft232h_mode != 'SPI':
raise ValueError("Method only available in SPI mode")
if bits != 8:
raise ValueError("Only bits=8 is implemented")
if delay != 0.0:
raise ValueError("The delay parameter is not currently implemented")
if speed != self.max_speed_hz and speed is not None:
self.max_speed_hz = speed
ret = [byte for byte in self._exchange_spi(readlen=len(values),
out=values,
start=start,
stop=stop,
duplex=True)]
self._send_server('stop')
return ret
[docs] def xfer2(self,
values: list,
speed: float = 6.0E6,
delay: float = 0.0,
bits: int = 8,
start: bool = True,
stop: bool = True) -> list:
"""Actually calls the :meth:`xfer` method with the same arguments."""
return self.xfer(values=values,
speed=speed,
delay=delay,
bits=bits,
start=start,
stop=stop)
[docs] def xfer3(self,
values: list,
speed: float = 6.0E6,
delay: float = 0.0,
bits: int = 8,
start: bool = True,
stop: bool = True) -> list:
"""Actually calls the :meth:`xfer` method with the same arguments."""
return self.xfer(values=values,
speed=speed,
delay=delay,
bits=bits,
start=start,
stop=stop)
@property
def _gpio_all_pins(self) -> int:
"""Reports the addressable GPIOs as a bitfield.
A :obj:`True` bit represents a pin which may be used as a GPIO, a
:obj:`False` bit a reserved pin.
Returns:
Bitfield of configurable GPIO pins
"""
mask = (1 << ft232h_port_width) - 1
if self._ft232h_mode == 'I2C':
return mask & ~self._i2c_mask
elif self._ft232h_mode == 'SPI':
return mask & ~self._spi_mask
else:
return mask
@property
def _direction(self) -> int:
"""Provides the FTDI pin direction.
A :obj:`True` bit represents an output pin, a :obj:`False` bit an input pin.
Returns:
Bitfield of pins direction.
"""
if self._ft232h_mode == 'I2C':
return self._i2c_dir | self._gpio_dir
elif self._ft232h_mode == 'SPI':
no_cs_mask = 0xFFFF - (self._cs_bit if self.no_cs else 0)
return self._spi_dir | self._gpio_dir & no_cs_mask
else:
return self._gpio_dir
def _read_gpio_raw(self) -> int:
"""Sends the MPSSE commands for reading all the FT232H pins, and returns the
bitmap of read values. Values are determined using 3.3V logic.
Returns:
Bitmap of pins values
"""
cmd = bytes([ft232h_cmds['get_bits_low'],
ft232h_cmds['get_bits_high'],
ft232h_cmds['send_immediate']])
fmt = '<H'
self._write_data(cmd)
size = calcsize(fmt)
data = self._read_data_bytes(size, 8)
if len(data) != size:
raise IOError('Cannot read GPIO')
value, = unpack(fmt, data)
return value
[docs] def get_gpio(self, gpio_str: str) -> int:
"""Reads the 3.3V-logic voltage value of the specified pin.
Args:
gpio_str (:obj:`str`): Name of the GPIO to be read
Returns:
3.3V-logic value corresponding to the input voltage
"""
self._queue.put_nowait(self._block_number)
if gpio_str not in ft232h_pin_nr:
raise ValueError("gpio_id should be in {}".format(
list(ft232h_pin_nr.values())))
gpio_bit = ft232h_pin_nr[gpio_str]
if not self._gpio_all_pins & gpio_bit:
raise ValueError("Cannot use pin {} as a GPIO".format(gpio_str))
# Changing the _direction and _gpio_dir bitfields
if self._direction & gpio_bit:
self._gpio_dir &= 0xFFFF - gpio_bit
ret = self._read_gpio_raw() & gpio_bit
self._send_server('stop')
return ret
[docs] def set_gpio(self, gpio_str: str, value: int) -> None:
"""Sets the specified GPIO as an output and sets its output value.
Args:
gpio_str (:obj:`str`): Name of the GPIO to be set
value (:obj:`int`): 1 for setting the GPIO high, 0 for setting it low
"""
self._queue.put_nowait(self._block_number)
if value not in [0, 1]:
raise ValueError("value should be either 0 or 1")
if gpio_str not in ft232h_pin_nr:
raise ValueError("gpio_id should be in {}".format(
list(ft232h_pin_nr.values())))
gpio_bit = ft232h_pin_nr[gpio_str]
if not self._gpio_all_pins & gpio_bit:
raise ValueError("Cannot use pin {} as a GPIO".format(gpio_str))
# Changing the _direction and _gpio_dir bitfields
if not (self._direction & gpio_bit):
self._gpio_dir |= gpio_bit
data = self._read_gpio_raw()
if value == 1:
data |= gpio_bit
else:
data &= 0xFFFF - gpio_bit
low_data = data & 0xFF
low_dir = self._direction & 0xFF
high_data = (data >> 8) & 0xFF
high_dir = (self._direction >> 8) & 0xFF
cmd = bytes([ft232h_cmds['set_bits_low'], low_data, low_dir,
ft232h_cmds['set_bits_high'], high_data, high_dir])
self._write_data(cmd)
self._gpio_low = low_data & self._gpio_all_pins
self._gpio_high = high_data & self._gpio_all_pins
self._send_server('stop')
[docs] def close(self) -> None:
"""Closes the FTDI interface/port."""
self._queue.put_nowait(self._block_number)
if self._send_server('close?'):
if self._send_server('_ctx.handle'):
try:
self._set_bitmode(0, ft232h_server.BitMode.RESET)
self._send_server([None, 'release_interface', 'dev',
self._index - 1])
except (IOError, ValueError, USBError):
pass
try:
self._send_server(['attach_kernel_driver', self._index - 1])
except (NotImplementedError, USBError):
pass
self._send_server([None, 'dispose_resources', 'dev'])
self._send_server('farewell')