Ardumoto shield running disconnected from Uno

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qurm
Posts: 2
Joined: Sun Jun 10, 2018 2:41 am

Ardumoto shield running disconnected from Uno

Post by qurm » Sun Jun 10, 2018 2:58 am

I am using an Ardumoto shield with an Uno, and have had it working fine, so I know it is not faulty.

I needed to use the Uno SPI pins with an SD card, and these pins clash with the ones required by the Ardumoto. So I have separated the shield from the Arduino, and made connections using cables to all the pins that I believe are needed, including 2 PWM pins, 2 direction pins, VIN and GND. The Ardumoto is powered from a battery, and it powers the Uno, and that starts up and the program runs fine.

So far so good, and it seems to turn the motors under test conditions with no load. However when I try to run the line-follower robot under PD control and a real load, then the motors seemingly stutter and have no real power.

I suspect that there are either a) some additional pins that are required, and are connected when the shield is directly on the Uno, or b) there is some kind of ground problem or current restriction that prevents full power flowing to the motors. There could be a software issue, but I dont think so.

This is the board I have - the previous version https://www.sparkfun.com/products/retired/9815

Can anyone comment if the Ardumoto should work they way I have it setup? I am missing something?

Thanks, Andy

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