GPIO state at boot

[simandcure]

Hello everyone,
Do someone knows if it is possible to fix the GPIO state at boot ? I'd like to control the state of GPIOs durig the boot sequence as I'm using relays.
Regards

[pcmanbob]

Hi.

You could try the "gpio" config command : viewtopic.php?f=117&t=208748

but you pi will still need to get to the point were this action is possible, so it may no be soon enough for your relays.

If its that your relay board is active low so the relays are switching on at boot, the other option is to add an interface circuit between the gpio and the relay board to make them active high.

[cleverca22]

https://www.raspberrypi.org/documentati ... xt/gpio.md

you can also use config.txt to set the default states for gpio earlier in the boot process

[6by9]

Follow the boot time default pulls as documented in section 6.2 of the SoC datasheet. If you don't then there will always be a slight glitch between power being applied and any form of software having taken over, processed whatever input, and set your GPIOs to any non-default setting.

By default GPIOs 0-8 pull up, whilst 9-27 pull down. No, those defaults can't be changed.

[Idahowalker]

Have you tried using external pull-up/down resistors that will receive their power prior to the RPi4 doing its GPIO thing?