I’m working on a robot with a club at my school. So far, our team has an H-bridge shield (https://www.freetronics.com.au/products/hbridge-dual-channel-h-bridge-motor-driver-shield#.WwI9omh_WEc) to drive motors in a toy tank. The H-bridge is powered by 6 AA batteries and the arduino is powered through the H-bridge shield with these batteries also. When everything is connected up and code uploaded to make the motors run forward, nothing happens - the motors don’t run. So far to debug, I’ve used a multimeter to check the voltages being output to the H-bridge from the arduino controller. These are all as expected. I’ve touched the motors to the positive and negative terminals of the battery and they run as expected. Lastly, I’ve substituted the H-bridge shield for a known working one. This did not fix the problem. I disconnected the motors and tested the voltage being output, which measured as +6V for both terminals of the motor relative to the negative terminal of the battery as well as relative to the ground pin. I also disconnected the jumper powering the arduino from the H-bridge shield and instead powered the arduino from my laptop. This did not fix the problem either. This seems completely contradictory. Any ideas on what the problem could be? Thanks so much ❤️❤️

  • 1
    Do you have a separate power supply connected to the shield? If not did you connect the jumper to power the motor from the Arduinos Vcc?
    – Gerben
    May 26, 2018 at 11:52
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    Measure the current going to the motors when connected to the shield vs when directly connected to the battery. Either your supply breaks down or you don't have the supply connected (see @Gerben comment). It would help if you draw a schematic of your exact setup (all conncections) using either pen&paper or the schematic tool when editing the question. May 26, 2018 at 12:51
  • here is the schematic .... looks like you require jumpers in JP1 and JP2 for enabling the data pins
    – jsotola
    May 28, 2018 at 16:34

1 Answer 1


It sounds either (i) like your motor driver is broken or (ii) your code does not operate the H bridge properly. Check which digital outputs pins of the Arduino control the H bridge and make sure that they do not short out the H bridge.

If you want to try another H bridge, this one is suitable for your application: https://www.pololu.com/product/2990 . I have worked with this before and it's very easy to use.

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