I am working on making my R/C Hummer autonomous and bought the MD01B to control the main drive motor. I am interfacing to the MD01B using the Arduino Nano. The supply battery voltage is around 8V (fresh charge) and I have all the connections going directly to the digital pins on the Nano, except for CS, which I have going to an analog pin. I have it to rotate CW and I am monitoring DiagA/B as well as CS. The PWM frequency is around 490 Hz.
Before testing with the Hummer motor (some sort of drill motor it seems) I tested with a smaller DC motor and everything seemed to work fine. I could send a relatively large command PWM signal (50% duty cycle) and the motor would react just fine. However, when I connect it to the Hummer motor (much larger) and send a command, you could hear it start to rotate (the whining of the motor), and then I would get a fault condition. DiagA: 1, DiagB: 0. I tried looking at CS to see what was happening, but there seems to be some noise on that line.
The first thing I did to debug was to ramp up the PWM slowly, but this did not work. Next I measured the No load current draw, when connected directly to the battery and got around 3A, and then with some load around 5.2A. This is well under the 14A rating of the motor. Next, I measured the resistance of the small DC motor, and then the hummer dc motor, and got 4.5 ohms and 0.2 ohms respectively. Looking online at some DeWalt drill motors, they also have very low resistance, so I figured that this is not the problem.
Does anyone have any suggestions? This has been bugging me for a few days now.
Thanks for your time,