Hi .
i try setting up ZED-F9R pHat module on Raspi4.
pHat was set → OS not boot
pHat was not set -->OS boot OK
(without pHat) OS boot → set pHat
“sudo cat /dev/ttyS0” brings me NMEA signal
but
with pHat OS boot → black screen
why?
:?:
Unfortunately we don’t know why, the only thing we can think of is your OS is expecting noting to be attached to one or more GPIO and when it finds something on a particular GPIO it hangs.
The following GPIO are used by the pHAT:
3,5,8,10,19,21,23,24,26,29
Plus 3.3v and ground.
You might try connecting the pHAT with with jumper wires and disconnecting one GPIO at a time until you find the one that’s causing the issue. Once you’ve found that you need to dig into Ubuntu to figure out what the OS is doing to that pin at boot to see if there’s a way to tell Ubuntu to ignore it and continue booting.