(01-28-2024, 04:33 PM)hifinet Wrote: Yes, you could share the 5V ultracap supply between the RPi and ProtoDAC. The Q7 goes to extreme lengths to isolate the DAC from the RPi. With an RPi4, there are four screaming cores, and you will be injecting that noise into ProtoDAC, around the Q7 isolation. Consider using the FifoPi MA (no isolation) and a RPi Zero W (single core).
Yes, just clip the leads.
@hifinet got it. So if I isolate the RPi4 with another GPIO stacking header then I wont have this noise issue. This requires another dedicated power supply for the RPi4. A couple more follow up questions -
1. When you say 'noise' is it the power/EMI leakage noise you are referring to (that the Q7 would have isolated if feeding the ProtoDac)? Because the signal path is still Pi > Q7 > ProtoDac.
2. If I use the FifoPi MA I'll still have the same issue, so not sure I understand the advantage of using FifoPiMa. Unless you are saying I anyways wont use the 'isolation' feature of Q7 so might as well go with FifoPiMa. You had suggested that the entire RPi/FifoPi MA/ProtoDAC stack could be simply powered by shorting J4 1-2 and 3-4, and applying 5V power to either the RPi USB or the FifoPiMA J3. But this is still not clean side power, will this be a problem?
