Fix for UAEFI sometimes not starting without USB connecteed

[gurov]

image.png (2.71 MiB) Viewed 988 times

from discussion on discord:


5vp does not light up with just 12v below a certain battery voltage, causing a no-start condition

this was traced down to a severe enough drop at the main 5v regulator that would cause the main MCU to power down, aborting enabling 5vp, entering a loop.

fix is rather crude, but it's to force 5vp to initialize forcefully, MCU or not.

10k resistor between pin 7 and 5v rail, like in the picture.

[AndreyB]

this was traced down to a severe enough drop at the main 5v regulator that would cause the main MCU to power down, aborting enabling 5vp, entering a loop.

We still do not know real root cause right?

Similar looking boards one would work another would not, right? https://github.com/rusefi/uaefi/issues/59

[gurov]

correct, still don't know the actual root cause, just breadcrumbs of symptoms with comparison to good board