[OCNC]

I've noticed that in the unipolar control board and the 3 & 4 axis BOB you're using 2x5 header pins for connections. Since only 3 lines are actually being used why a 2x5 header? Why not just 1x3? Also why did you bring out pins 1 and 9 to a solder pad? Is there some future use in mind regarding these choices?

Thanks!

Chris

[pminmo]

Several reasons.
1. A ground inerspersed with a signal is less prone to noise and adjacent signal coupling.
2.10 pin IDC connectors and cable are more easy to come by.
3. If you don't want to use IDC cable and headers you only wire discretely what you want.
4. You have the flexability to share one 5VDC regulator.
5. 5VDC might be needed to support opto isolation.

Regarding pins 1 and 9. Two of the boards, the 3977 and L297-8 use pin 1 for enable. The pad gives the flexability to wire as you see fit. Pin 9 can be arranged to give or get 5vdc to those boards also as well as the discrete unipolar.

Phil

[OCNC]

Several reasons.

3. If you don't want to use IDC cable and headers you only wire discretely what you want.

Phil

Would it work equally well to use shielded cable with a dedicated ground wire as well as a grounded shield drain wire?

Thanks again!

Chris

[pminmo]

Would it work equally well to use shielded cable with a dedicated ground wire as well as a grounded shield drain wire?

Thanks again!

Chris

Yes, probably even a little better, simply use the adjacent gnd pin. All the even pins are wired to ground.

Phil