A Panda II I’m running with a shield that contains a a quad OP amp IC (LM324AN) running off the 5 volt Panda supply. When the Panda goes in and out of hibernation there is a small ~50 mv spike in the supply voltage. Unfortunately the amplifier as configured uses an voltage offset of ~1.6 volts that also sees the spike at the input and thus also gets amplified. The offset is needed to get a full 0-3.2 volt swing for the Panda A/D. After amoplification there are full scale voltage spikes that can present problems in analyzing the digitized signal (see pic).
I’ve tried adding 320 uf of filtering on the 5 volt rail, but with little effect. I can add another regulator to power the amp off the 12 volt supply and bypass the Panda power circuits, but don’t want to do that unless absolutely necessary. I suppose I could also try another amplifier circuit or forgo the offset by tying to ground and use only half the signal, but not an elegant solution either.
I doubt there’s a simple solution, but I thought this might be worth mentioning in case it helps someone else. On the other hand if someone has a idea I’m all ears (small Yoda joke).