A few questions about PICStep realisation

[gaga2410]

Hello,

I'm going to make PICStep board and I have a few questions and need your advice.
I choose the version with ICSP socket and the PC interface board wich only work with version <3.1.

- What is the best choice for the firmware with or without timeout protection ?

- What is the minimum motor courant I can use ? I've motors rated at 1A and 1,2A. Are they good for the application with PICStep ?

- About the motors power supply : what type do I use ?

Thank you very much for all the help you can give me.

Best regards.

Gaga

[dtman2]

I can't answer the first question, but as for the other two -

1 A or 1.2 A will be fine, use a 20k resistor for 1A, or whatever value you have above 16.6k for the 1.2 A. As for a power supply, I am using a 28V supply and it works nicely but you can go all the way up to maybe 40V, if you go above that then you need some back emf protection diodes or whatever. As for the current rating of the supply, assuming you have 3 steppers @1A you can get away with less than 3A supply , maybe as low as 1A with some nice caps to hold it up during peaks. You will also need a lower voltage to supply the pics and other circuitry, 12V is good at maybe an amp or less, I picked up a 12V 1A adapter for 3 dollars on ebay that works ok. If you try to use the motor voltage to run the onboard regulator it will overheat if your motor voltage is much above 15 volts I guess.

Heatsinks are sort of important too, I used pentium heatsinks with fans, one on each channel, since I had them kicking around. You probably dont need fans running only one amp but you might want to upgrade your steppers later so why not set it up right.

[gaga2410]

Thanks dtman2,

It's very useful for me.

[gaga2410]

I've another question :

Can I use another board to convert parallel to usb or rs232 ? Is there any problem to do this, like compatibility with pc software ?

Thank you and a hello from Reunion Island to everyone !

[dtman2]

I am not sure I understand your question. If you are asking whether you can use a usb to parallel port adapter to drive the picstep, the answer is no as far as I understand it, at least with EMC2 which is what I use. THe exact timing of the step pulses is critical to the smooth operation of the stepper and sticking a usb converter in there which has unknown delays and strange driver programs will prevent it from working. I believe the same applies to the other software based approaches to driving the step/direction inputs on the picstep. I think that at least until you get it running it is probably best to use the standard approach of driving the picstep from the parallel port via a breakout board of some sort. Use an old pentium 3 or something. You can experiment with more exotic approaches after you get it running, but there are probably more important things to worry about.

[gaga2410]

Thanks for your answer ! It's exactly what I want to know.

Bye !