I am having a nightmare with this damned circuit.
I am using a Texas Instruments SN7544 0NE (thats a zero, not an o) integrated circuit. It has two h bridges.
Here is the spec sheet:
http://focus.ti.com/lit/ds/symlink/sn754410.pdfHere is a tutorial using the same chip and the microcontroller I am using:
http://itp.nyu.edu/physcomp/Labs/DCMotorControlI have checked 30 times, everything is wired correctly. I have the chip properly grounded across the bread board. Here's the problem -
Whenever I turn on the microcontroller and tell the h bridge to go, I hear the motors whining ever so slightly - they are running on a 9 volt battery as opposed to my controller's 5 volt power supply (from the computer right now). I remove the negative lead of the motor and place it directly into ground, leaving the positive lead in the h bridge circuit. Sure enough the motor runs, at the speed I wanted it to as well! I even tested it - changing the PWM value when doing this does indeed change the speed of the motor.
This would be great IF I wanted to run the motor in one direction. Telling the H bridge to reverse directions this fails miserably as I have to plug the negative lead in and put the positive lead to ground!
Why is it when I have the chip wired correctly it is whining ever so slightly and refusing to move?
Any help would be GREATLY appreciated. This problem is holding back two projects and maybe soon to be three!