Raspberry Pi 3: how do I enable UART and GPIO access?

[tmplt]

I'm working on a project with a Raspberry 3 Model B where I need to use SPI, UART and the GPIO pins. I'm building a bootable image by importing <nixpkgs/nixos/modules/installer/cd-dvd/sd-image-aarch64.nix>.

By some help of @sorki, I've managed to get SPI up and running by applying a device-tree overlay on linuxPackages_4_19 using #79370. But thus far I've had no success with UART or GPIO.

When using boot.kernelPackages = pkgs.linuxPackages_rpi3 (the only kernel tried where the expected /dev/ttyAMA0 appears), a UART loopback test (shorting the UART TX/RX pins and using screen /dev/ttyAMA0 115200 to enter some bytes) fails.

I haven't digged as much into GPIO support yet: thus far I have tried to use gpiozero which fails because it tries to parse out a "Revision\t:" field from /proc/cpuinfo that does not exist.

Is there a known way to properly enable GPIO and UART access?

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For sake of context, my NixOS configuration can be found here.

[Gaelan]

For GPIO, see if the commands from libgpiod work. Those use the new character device ABI (/dev/gpiochip0), which is the preferred way to do such things these days. If you can find a library for your language that uses that ABI, that would be best.

[stale]

I marked this as stale due to inactivity. → More info

[adminy]

will this work for orange Pi 5 plus also?

[sorki]

will this work for orange Pi 5 plus also?

Not sure what exactly are you asking about but both libgpiod and UART should work out of box on most boards.

[sorki]

Looks very dated and no sure if there's anything actionable here, feel free to reopen if needed.