I need some help with a Raspberry Pi robot I am attempting to put together.

I'm using an L298N h-bridge to manage both DC motor wheels. I have a simple python script on the Pi which should simply drive the bot forwards and backwards. However, the wheels don't move. Instead I just hear a low pitched whine.

I am powering the Pi and the h-bridge from 5V usb ports off a power bank. For the h-bridge, I connected each motor to A and B, to ground and to 5V.

To eliminate the potential that both DC motors are damaged, I put the positive and negative leads from a 9V battery to the solder points of each DC motor and both respond ... spinning fast in one direction and in the reverse when I switch the polarity of the battery leads.

So, I got my multimeter and tested the current at the h-bridge power connection and I get just under 5V as pictured below: enter image description here

When I tested the connections for each motor, I got 0.23V - which I'm guessing is the problem.

Can anyone please advice on how I can solve this problem and get my robot moving?

  • tested the current get just under 5V .... you did not test the current, you measured the voltage .... unit of measurement for current is amp (A) – jsotola Jun 7 '19 at 17:45
  • your power supply is unable to provide enough current to drive the motors – jsotola Jun 7 '19 at 17:48
  • your troubleshooting process is flawed .... if the motor does not turn when connected to a bridge that is powered by 5 V supply, then use the 5 V supply directly to test the motor ... do not use a 9 V battery to test the motor – jsotola Jun 7 '19 at 17:52
  • You could probably get this result if your h-bridge is wired into the circuit wrongly, among other things. – Brick Jun 7 '19 at 19:10
  • @jsotola: I take your point. I tested the motors using a 5V connection and the wheels responded – sisko Jun 7 '19 at 23:33

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