Motor Stepper Example

[mslaney]

Get it?
On and off.... :-)

I'm having a problem...
In it's simplest form, would the following be a brute force method of driving a bi-polar motor?

(PIC 16F876)
(defines, includes, and OSC set....)
(tris a, b, and c set to 0)

speed var word
speed = 100 'just an arbitrary number - will eventually ramp up to max

Spin:
porta = %00000001
pause speed
porta = %00000100
pause speed
porta = %00000010
pause speed
porta = %00001000
pause speed
goto Spin


When testing this with LEDs, this seems to work fine - the LEDs flash separately. However, when I attach the motor, nothing moves and the LED's flash in pairs.

Pinout:
porta.0 -> IRL510 -> LED/CoilA
porta.1 -> IRL510 -> LED/CoilB
porta.2 -> IRL510 -> LED/CoilC
porta.3 -> IRL510 -> LED/CoilD

If it matters, it's a work project that is behind schedule. A quick answer would be truly appreciated. I might even send you a check for $5 USD!!! :-)
Is there a single IC like the UCN5804 but for bi-polar motors instead of unipolar?

[mslaney]

I guess what I 'm asking is....Do I need an H bridge or is it a function of the program?

[hansknec]

If you are driving a bipolar motor you will need a dual H-bridge circuit. (2 coils each need dual driving polarity). The code presented earlier in the thread appears to me to be for driving a unipolar motor. Since you appear to be familiar with the allegro driver chips you should see that they would only require two outputs from a PIC to drive the motor. One is a direction bit and the other is toggled the amount of steps you want. I prefer using unipolar motors myself because they are easier to build a drive circuit using only 4 FETs.

John