Prop to motor driver interface question
Hi
I'm using my Prop to driver a pair of Allegro A3980 stepper motor drivers. Allegro spec sheet : www.allegromicro.com/en/Products/Part_Numbers/3980/3980.pdf.
I've modified the example LED blinker code from the manual to drive the step pins. The problem I'm getting is that sometimes one or other motor will 'stutter' a little, as if they're getting interference from somewhere. I've checked the fault flag pins on both chips while they're operating but all of the pins stay in their 'no fault' state i.e. both pins on both chips stay high. The problem seems to go away though when I connect my meter between ground and one or other of the 'step' pins. Something similar happened with the opto-switches I'm using. See this topic : http://forums.parallax.com/showthread.php?p=624334
Do I just need to connect a resistor between the step/direction pins and ground, or do I need to do something else. If its just a case of adding some resistors, how do I work out the value of the resistors that I need?
Thanks
I'm using my Prop to driver a pair of Allegro A3980 stepper motor drivers. Allegro spec sheet : www.allegromicro.com/en/Products/Part_Numbers/3980/3980.pdf.
I've modified the example LED blinker code from the manual to drive the step pins. The problem I'm getting is that sometimes one or other motor will 'stutter' a little, as if they're getting interference from somewhere. I've checked the fault flag pins on both chips while they're operating but all of the pins stay in their 'no fault' state i.e. both pins on both chips stay high. The problem seems to go away though when I connect my meter between ground and one or other of the 'step' pins. Something similar happened with the opto-switches I'm using. See this topic : http://forums.parallax.com/showthread.php?p=624334
Do I just need to connect a resistor between the step/direction pins and ground, or do I need to do something else. If its just a case of adding some resistors, how do I work out the value of the resistors that I need?
Thanks
Comments
·· I would have a look at some code called PAP
·· It even has quadratic equasion for doing ramping.
· Jim
I am fairly sure the problem lies with electrical interference getting on either the step or the direction pins, as the problem goes away when I place my multimeter (in voltage mode) between the step or direction pins and ground. So I think I need to add resistors between the step/direction pins and ground. My question really is whether this is the right approach or should I try something else? If it is the right approach then how do I work out which resistors to use?
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Tracy Allen
www.emesystems.com
I seem to have solved the interference problem. I soldered some 10k resistors between the STEP pins and ground and that seems to have cured the problem