ProtoDAC TDA1387 X8 project

[michaelagiles]

Normally with the MA, J3 (5V) only provides power to the Raspberry Pi below via J1. When J4 jumpers 1-2 and 3-4 are shorted, this apparently provides common J3 power (5V) to the MA and the top side GPIOs J2 and J3. J5 (3.3V "clean power") is then left unconnected. MA must have 3.3V regulators on board to supply power to the MA??

Question: What are the voltage readings of J4 jumpers when 1-2 and 3-4 are shorted? Are they both 5V or is 1-2 5V and 3-4 3.3V?

My reading of the Ma manual is that the 3,3v regs are on the Rpi board and that this is available on pins 1 and 17 of the Rpi GPIO connector.  If the 1-2. 3-4 jumpers are NOT shorted then you must power the RPI directly and the Ma with 3,3 at ;5.

Pins 2.4 on the Rpi are 5v as you know and changed to 3,3 only on 1 of the Ma GPIO connectors. I had this confirmed directly by Ian. He was very responsive to direct email questions BTW.
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I don't know the voltage on the jumper pins. And at the moment I am just enjoying the music!
MG