I have a boot issue with a system consisting of

  • Raspberry Pi 4 B+
  • Raspbian 10 (buster)
  • 7" capacitive touch display (the "official" one) and a
  • custom shield that pulls BCM17 (pin 11) high, when external 12V present.

Everything works fine with BCM17 when the system has booted. I can read the pin and it reflects the status of my external 12V.

But when I first apply 12V and then the Pi supply voltage, the system won't boot.

  • the system won't boot. what happens instead? what happens without the "official" (why is it in quotes) touch display? Commented Jan 26, 2021 at 9:17
  • by "what happens instead" I mean, does the activity light flash? does anything at all appear on the display? etc etc Commented Jan 26, 2021 at 9:22
  • What happens instead: Red led constantly on, green led constantly off. Display shows nothing. No SSH access from outside. When I disconnect both the FPC cable and the power jumper cables that came with the Display and power up, the behavior is the same. Seems not to be display-related.
    – Simon
    Commented Jan 26, 2021 at 16:36
  • Oh, so the green led doesn't even flicker at all. Do you need/have any overlays loaded for this "custom shield"? Commented Jan 26, 2021 at 22:27
  • Exactly. The shield only uses GPIOs und the I2C. I activated the latter using raspi-config. The only line starting with dtoverlay in '/boot/config.txt' appears to be DRM related: dtoverlay=vc4-fkms-v3d
    – Simon
    Commented Jan 27, 2021 at 14:18

1 Answer 1


My bad, I was drawing too much current from the pin. Apparently this led to the startup issue.

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