Dual MC33887 motor driver carrier 712

Hi, I’m trying to drive a couple motors using the 712 Dual MC33887 motor driver carrier, and having no luck at all. What does it take to get a motor to run with this? The only way I’ve gotten any motion out of a motor is to have the inputs connected per the datasheet:

"For a DC motor to run, the input conditions need be as follows: D2 input logic Enable input logic HIGH, D1 input logic LOW, HIGH, FS flag cleared (logic HIGH), one IN logic LOW and the other IN logic HIGH (to define output polarity). "

The motor does not actually run, and the LEDs do not light. But, if I disconnect and reconnect the Enable input, then the motor wiggles and the lights blink momentarily.

I am using the + and GND connections at the center of the input side of the board to connect the other inputs to high and low.

Please keep in mind that I"m a mechanical engineer, and this stuff is all highly confusing…a detailed tutorial would be very nice, or at least some slightly detailed instructions about what each input actually does. I would like to use either an analog input or PWM input (from a VEX controller) to control motor speed.

Thanks!

Hello,

It looks like that quote isn’t quite right, but you probably have the right connections. The fault status is an output from the H-bridge, so make sure you’re not hard-wiring that to Vcc. If your motor is moving a bit and stopping, I suspect the motor might be too big for this driver. What kind of current should it draw? What is the fault status line reporting?

This motor driver won’t work directly with an analog voltage control signal. I’m not sure what the VEX PWM output capabilities are, but make sure it’s a real PWM output capable of 0-100% duty cycle, not a control signal for RC servos.

The datasheet covers what the input pins do on page 21: EN1 and EN2 are for direction select, D1 and !D2 are for disable (you can use these for PWM), and EN is for enabling the whole thing. If you want more details, you’ll have to give more details about what you don’t understand.

- Jan

What are you using as a power source? Please note that the control signal inputs have maximum voltage ratings of -0.3 to 7.0V. If your supply voltage is higher than 7.0V, you could destroy the chip by V+ to drive the control inputs high.

- Ben

That could be the problem…or one of them, anyways.

I’ll find some other way to do what I want. Thanks for the replys!