clunks / missing steps - DM856 and single pulse operation

[irving2008]

Exactly so and I think that may be a partial cause of the problem. In source mode those pins will only drive the Opto at about 7mA, it really needs 12 or more, and they will be susceptible to ground noise. In sink mode they can easily manage 15mA. I'm guessing you're driving the DIR line the same way and driving it high, which would also explain the occasional reversal.

As a first step, excuse the pun, I'd change this to use an active low approach.

[dsc]

Yes at the moment I'm driving the whole lot like this ie. source rather than sink. I have the same problem for a PWM signal to another driver for a bigger Nema 34 motor. I will change all connections today, change the logic to be low active and do a test with the PUL signal alone.

Thanks again irving2008!

Regards,
Tom

[dsc]

Ok I've changed it as per the manual, all outputs sink'ed, so PUL+ connected to 5VDC and PUL- connected to the output pin of the PIC16F887. Unfortunately it still isn't working, here's a video which shows it better than I can describe using words:



[best to watch in HD and full screen mode. The clicks are tactile switches used to drive the motor]

I've tried using both PUL and DIR as well as PUL alone. I've tried making the pulse wider and using a bigger delay between the DIR and PUL. No change :( I also tried using a scope to check the state of the signal but to my surprise it makes the circuit stop working, I guess the 0VDC connection from the scope grounds the PIC output pin when trying to measure and there's no change on the output then. Not sure how to check what the pulse is like on the PUL+ / PUL- terminals.

Regards,
T.