TROUBLESHOOTING CIRCUITS

Wiring circuits, using electronic components and writing software isn't easy -- even professionals spend a lot of time "debugging" their hardware and software designs.  So, if you're having issues, don't feel bad, it's a typical part of any programming and electronics work you'll ever do.  Below, we offer some suggestions on how to work through the issues you might be having with your projects.  If you're having issues that aren't addressed in any of the sections below, feel free to visit our support page at: http://www.raspberrystem.com/support.

CIRCUIT ISSUES

If your circuit isn't working, there are lots of potential issues you could be encountering.  When this happens, the best approach is one that tests each part of the circuit piece-by-piece until the problem is identified and fixed.  The process involves starting at the very beginning (the Raspberry Pi computer), working our way up to the breadboard, examining each of the components to ensure they've been placed/wired correctly and then testing for continuity around the entire circuit.

Here is a step-by-step checklist that you can use to efficiently test your circuit to resolve issues.  After following these troubleshooting steps a few times, you'll start to get a hang of how to resolve issues even more quickly on your own:

1.  Verify that the Raspberry Pi computer is receiving power

The first step is that you want to ensure that the Raspberry Pi computer is powered on.  This is very easy to verify -- just look to ensure that the red light on the front of the Raspberry Pi is illuminated, as follows:


If the light on the Raspberry Pi is not illuminated, you'll want to check the following:

2.  Verify that the connector board is being powered correctly

Now that we're confident that the Raspberry Pi is powered on, we want to ensure that it is correctly connected to the Lid Connector Board with the Ribbon Cable.  To verify this, do the following

  1. Take a working LED and place the longer metal lead in one of the holes marked "3.3V" on the Lid Connector Board

  2. Take the shorter metal lead of that LED and place it in one of the holes marked "GND" on the Lid Connector Board

At this point, the LED should be illuminated, as follows:

PIC OF LED IN LID CONNECTOR

Note:  Don't leave the LED like that for very long, as without a resistor, the LED can be damaged.

If the LED is not illuminated, you'll want to check the following:

3. Verify that the breadboard is being powered and grounded correctly

Assuming the Lid Connector Board is receiving power, the next thing you'll want to verify is that your breadboard is receiving power and ground correctly.  We will assume that you already have a wire running from a hole marked "3.3V" in the Lid Connector Board to a hole along the red strip of the Breadboard and that you already have a wire running from a hole marked "GND" in the Lid Connector Board to a hole along the blue strip of the Breadboard.

To verify that the breadboard is correctly receiving power, do the following:

  1. Take a working LED, and place the longer metal lead of the LED somewhere along the red (power) strip

  2. Take the shorter metal lead of the LED and place it somewhere along the blue (ground) strip.  

If the power and ground strips on the breadboard are working correctly, the LED should illuminate.  

Here is an example:

INSERT FRITZING OF LED ACROSS POWER/GROUND

Note:  Don't leave the LED like that for very long, as without a resistor, the LED can be damaged.

If the LED is not illuminated, you'll want to check to ensure that 3.3V is connected to the red strip and GND is connected to the blue strip.  There is nothing stopping you from (purposefully or accidentally) wiring it backwards, with red strip being wired to GND and blue being wired to 3.3V.  But, if you do this, the red strip will become the ground and the blue strip will become the power.  Then, all of your components will need to be wired with that convention.


4.  Check that each component is being wired and programmed correctly

Once you are confident that your breadboard is being powered and grounded correctly, the next step is to verify that each of your components is wired correctly and functioning properly.  We have included sections below to troubleshoot each of the components provided with the RaspberrySTEM kit.  Here are links to troubleshoot each of the individual components:

-  LED

-  Button

-  Accelerometer

-  LED Matrix

6.  Test continuity between various points in the circuit

If you've verified power and ground are working correctly, and you've verified that each of your components are wire correctly and functioning correctly, but your circuit still isn't working, it time to do some investigation into whether the wiring between components was done correctly.

7.  Verify your code is working as expected

LED ISSUES

LEDs are relatively simple devices, but there are still some challenges you'll face when using them in your circuits.  Luckily, fixing LED issues should be pretty quick and easy once you get used to working with them.  Here are some tips on how to solve issues with LEDs:

1.  Verify that the LED is working properly

Assuming you have a verified power source (either the battery used in the "Your First Circuit" project or the Lid Connector Board), you can place the LED with the long lead attached to power and the short lead attached to ground, and verify that it illuminates.

Note:  Don't leave the LED like that for very long, as without a resistor, the LED can be damaged.

2.  Verify that the LED is oriented correctly

If the LED isn't working with a verified power source, you should ensure that the LED is oriented correctly, with the longer lead attached to the power and the shorter lead attached to ground.  To be certain that the LED is oriented correctly, you can always try turning it so that the leads attach the other way and see if it works that way.  If the LED doesn't work in either direction, there is a good chance that your LED isn't functional.

3.  If attached to a GPIO, verify that the LED is wired correctly

If you are attempting to attach an LED to GPIO, you'll want to ensure that the longer lead is attached to power and that the shorter lead is attached to the GPIO, as follows (in this example, we're using GPIO14):


4.  If attached to a GPIO, verify that the code reflects the correct GPIO being used

Once you have verified that the LED is working correctly and that it is correctly wired, you can use the following short piece of code to verify that the LED is wired correctly (note that the code reflects using GPIO14 for the LED):

BUTTON ISSUES

1.  Verify that the button is oriented correctly on the breadboard

2.  Ensure the button is fully inserted into the breadboard

3.  If attached to a GPIO, verify that the button is wired correctly

4.  If attached to a GPIO, verify that the code reflects the correct GPIO being used

5.  If still not working, you might want to verify that the button works correctly (unlikely issue)

ACCELEROMETER ISSUES

1.  If you see or smell smoke, verify that the accelerometer is oriented correctly

2.  Ensure that the accelerometer is wired correctly

3.  Test the accelerometer with some simple code

LED MATRIX ISSUES

1.  Verify that your LED Matrix cable is installed correctly  

2.  Verify that your display is oriented correctly on the circuit board

3.  Ensure that the LED Matrix is wired correctly

4.  Test the LED Matrix with some simple code