Arduino Motor Shield output Voltage problem

Using Arduino Motors, Mechanics, Power and CNC
#1

Hi, everyone. This is my first Arduino project, I really need your help. I tested the DC motor using in this project by simple code, it can work only one direction. So I measured the motor shield output voltage and found something wierd. The PWM value is the same for both motor working direction. But the out voltage get from is -7v and 0.1V(this should be 7V). What's the problem?

Thanks in advance.

#2

Set the PWM output to 255. Then the output voltage should switch between + the supply voltage to - the supply voltage as you change direction. If one of the voltages is still WAY off there is probably a problem in the H-bridge.

#3

Thanks a lot John. One more questions, did you see my last post about motor running problem? What's your point about that?

#4

virgil:
Thanks a lot John. One more questions, did you see my last post about motor running problem? What’s your point about that?

I probably saw it but I don’t remember it. If I saw it and didn’t answer I probably had nothing to add.

#5