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just lay out the pcb with the normal microcontroller cktry on one side and the h-bridge
cktry on the other side, and only connect them together at a single ground point. Some
people will use an inductor [choke] or ferrite to make the connection. -
once this is in place, simply run the h-bridge control signals from the microcontroller
across to the h-bridge. Always good to put series-Rs in these lines to help protect the
uC from motor noise feeding back from the h-bridge. -
locate the main terminals for motor power on the h-bridge side of the board, so the
motor currents never cross to the other side, and never flow through the single point
ground connection of item #1. Add bypass [0.1 uF] and reservoir [100 uf or more]
caps right at the same terminals. -
it's best to use 2 separate external power supplies, one for the logic part and another for
the motors. If you can't do this, then the next best thing to do is connect a single supply
to the motor side, and jumper "1" wire over externally to supply logic power. This way,
the motor currents are always confined to the h-bridge side, and not flowing between
the 2 sides. Don't make an external ground connection between the 2 sides, as then you
will have a ground loop. -
if you have analog cktry on the pcb, confine it to a separate area from the digital logic
cktry, and also on the opposite side of the pcb from the h-bridge cktry.