FreeLists / si-list / [SI-LIST] Ground plane question

["Mike S." <powersurf@xxxxxxxxx>]

Hello to all
I'm designing a daughter card (more like a connector expansion card)
for digital low frequency PWM input/output. This daughter card
connects to the motherboard with 2 stack connectors (similar to PC104
but a lot smaller) separated by 1 inch. Both these connectors have
ground pins. One is only for input, and the other only for output. The
daughter card is a dual layer board. Since the trace routing is very
simple I will use the bottom layer as a ground plane. My question is:
Should the ground plane be connected to both connectors, or, to avoid
ground loops (with the motherboard) should I do two ground planes
(both in the bottom layer) one for each stack connector? One ground
plane would be under the input stack connector and the digital input
connectors. The other would be under the output stack connectors, the
digital output connectors (these are 3 way connectors to drive servos)
and an alternate power supply to drive the Vcc pin of each output
connector to the servos (possibly high currents).
Any pointers, suggestions, design examples?
Thanks in advance
Best Regards
Bruno
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