Dear Emlid Community
The Navio2-RPI stack works great. Now, I would like to power an additional circuit from the power pins on the 40 pin stack connection header (5 V pins 2 and 4,3.3 V pin 1 and 17 and GND pins 6,9,14, 20,25,30,34,39 ). Related to this I wonder about how the 5 V and 3.3 V pins are behaving when powering the RPI-Navio2 stack from the different power sources so I don’t kill my additonal circuitry.
In the Navio2 docs I can read that the power supply is tripple redundant (Micro USB from the Pi, Navio Power Port and Servo Rail) and in the Forum I was learning that all power supplies are protected with diodes:
https://community.emlid.com/t/navio-2-power-question/4186/3
To my questions 
-
When I provide power from the RPI micro USB port then I assume that 5 V and 3.3 V on the header are generated on the RPI. Correct?
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When I provide power from the Navio 2 power module only (5.3 V output):
a) Are then the 5V header pins on 5V from the RPI or on 5.3 from the Navio2?
b) Max current on the ADC, I2C, UART 5V terminals?
b) Is the 3.3V generated from the PI or from the Navio2? (max current?) -
When I provide power from the Navio2 servo rail only with voltage X
a) Are then the 5V header pins on 5 V from the RPI or on voltage X from the Navio2?
b) Is the 3.3V generated from the PI or from the Navio2? (max current?) -
And lastly: which voltage would the 5 V and 3.3 V header pins have when a mix of the 3 powersources is applied? This probably equivalent to know how exactly are the diodes placed between these power busses.
Thanks a lot for the support.
Greetings, Damian