ESP32 UniShield Grounding
I really like the ESP32 UniShield I recently purchased. A lot of thought went into making it flexible to accommodate the different equipment configurations and needs of brew automation.
I was surprised to see that there are two sets of larger screw terminals for power on the base board near to the higher current drivers, but there is no larger terminal on the base board for a ground return.
I understand that there are 4 small gnd terminals on the riser board, and you do have a note to star pattern connect the gnd, but was there a specific reason a gnd terminal was omitted on the base board?
It’s a fair question. First, there is no big ground terminal because there is no current flow back to ground needed on the board. We could have added big ground terminals but those would only serve to do what normal terminals do, which is tie wires together. So to give you flexibility, save size and cost, we left them off so you can pick ones you like. The only ground the UniShield needs is to reference it for its own power, which is very little given the on-board power supply, the micro-controller, and the driver chips’ logic.
One could argue that it would have been convenient to have a ground terminal next to each P / D pin so output devices could be solely wired to the UniShield and that was a sincere consideration. Initial designs had them. But we opted to reduce space and cost and allow users to bring all grounds back to one common terminal block that they supply to keep the star pattern implemented.
That all said... thank you for the feedback!