Hi
@mfethe,
Sorry for the late reply.
Thanks for doing this analysis. Good Job! Via this you are getting close. The conclusion so far: Your
Arduino Dues 3.3V supply gets overloaded which is caused by the Ardumower
mainboard. It's or the header/pin -interface or a something else on the
mainboard.
I guess somwhere a bad soldering / short circuit resulting in a overrload of the 3,3V.
So far as I can see in the drawings, the
mainboard is not using the 3,3V coming from the
Arduino. It's only used for the LED indicator [D19] labeled as "+3,3V":
And the 3,3V is wired towards pin header [P34] (for dev purpose I guess)
As a very quick workaround. Why not bending the 3,3V pin coming from the
Arduino ? Via this you isolate the 3,3V as it will not make any connection with the
Mainboard and the complete solution will remain stable which allows you to continue with your build. During the time you continue with the build you will find out soon the root cause...