I am looking into the “Dual MC33926 motor driver carrier” and have a question about the control pins (D1, D2, IN1 and IN2).
The description states: In a typical application, three I/O lines are used to connect each motor driver channel to a microcontroller:
IN1 and IN2, for direction control,
one of the disable lines, D1 or D2, for PWM speed control,
The control lines can be reduced to two pins per channel if PWM signals are applied directly to the two input pins with both disable pins held inactive.
In other motor controllers I used I used one normal digital pin for direction control and one PWM-pin for speed control. Is such a configuration also possible with the Dual MC33926 motor driver carrier ?
The mentioned tread suggests a solution for motor control with just two pins by means of “a transistor”.
In this tread however an alternative is stated “Personally, I would tie D2 HIGH and apply PWM on one of the input pins, with the other input pin setting the direction. So if the direction input pin is Low, the width of the High period of the PWM signal will vary the speed of the motor spining one way and if the direction pin is High, the Low period of the PWM signal will vary the speed of the motor spinning the other way (inverse PWM)”.
Agree. Best is to do a thorough test yourself. I’m going to do that when the motor controllers are received. Found out yesterday that at least will take a week.
Yesterday I received the motor controllers. Today I tested the control possibilities for direction and speed of the motors.
Seems that both configurations offers the same possibilities. I think I'm going for configuration B because I expect that the implementation of the mecanum algorithm is easier in B then in A (signal mixing …). Further has the Mega sufficient PWM-pins, so a lack of PWM-resources is not an issue.
Summarized the test results in a pdf-doc and placed it in my public dropbox folder. Better to read this way? Bit cumbersome (I think). What is a more convenient way to share pictures and docs @ LMR? Haven’t seen an upload possibility for artefacts like that, or do I mis something?
Find my DSO later today and will take a closer look at the controller signals.
