Can an A3955 be used for step/dir input ?

[epineh]

I have been looking at the Allegro site and was interested in the A3955 bipolar stepper driver chip. It's description is to allow digital control of a stepper motor.

http://www.allegromicro.com/en/Produ..._Numbers/3955/

My question is can the chip be used "out of the box" in a step/dir type of application or is a microcontroller needed to generate the step sequence? Direction is simple enough, the phase input pin sets the direction but the step seems to be a function of D0 D1 and D2, which also set the microstepping current.

Maybe a binary counter is required.

I realize two chips are needed for one motor, but if standard step/dir can be used then it would make a nice compact driver, possibly to be attached to a stepper (small motor of course)

Russell.

[CountZero]

Take a look in the datasheets truth table. I took a quick glance and it seems like a counter(or two) with some logic around could do it, but a micro would not be very expensive and give some more versatility.

OTOH why not go for something like A3977 with built-in step-dir interface(and more current.. less voltage however). Might be never/better chips around too.

[epineh]

Thinking the same thing, I know Phil (Pminmo) has boards, layouts and schematics for the 3977, I actually requested samples of the 3955 without thoroughly checking the datasheet and missed that it was a digital input step control

The response from Allegro was definately fast, I had the chips here in Australia in just over a week, nice

Russell.

[CountZero]

Just sample some a3977's too

Xerxes has nice boards too: http://www.students.tut.fi/~kontkant/a3977.php.html

Edit: BTW what time do you have down there in Australia? Shouldn't you be sleeping

[epineh]

They are nice boards, thanks for the link

Lol 5.30pm was my previous post, I know I am getting old, but that is a little early for me to call it a night, heh

Now to see if I can get some more samples...

Russell.