Raspberry Pi questions re GPIO support in Debian

[seamusdemora]

I think I'd like to try installing Debian on one of my Raspberry Pi. I've seen the documentation/installation instructions, and that all seems clear enough. What I'd like to get clarification on is with respect to how "GPIO programming" will work under Debian.

1. Raspbian has a "device tree", and this is used in the construction of a wide variety of "overlays" which expose both general and specialized GPIO functions. Does the Debian installation for Raspberry Pi have that device tree functionality and overlays available?

2. Raspbian (starting w/ bullseye IIRC) included the `libgpiod` library (the older 1.6 version). `libgpiod` included another package called `gpiod` which was a "container" for several user tools (gpioinfo, gpioset, etc). I see that Debian has the `libgpiod` package available. Is this package pre-installed in the Raspberry Pi images - or must it be installed after installation of the OS? I ask this question b/c I've heard a report suggesting that `libgpiod` was "broken" in the Debian RPi distribution.

Thanks for your help!

[Linuxgaming1824]

- Raspberry Pi Debian images -
https://raspi.debian.net/

- Debian RaspberryPI wiki -
https://wiki.debian.org/RaspberryPi

- Installing 64-bit Debian on a Raspberry Pi 4 -
https://david.wragg.org/blog/

I have no idea what the answers to your questions are, but it sounds like you should take a look at these pages first,
it sounds like a cool project anyways let us know what you find out

[seamusdemora]

I'm afraid you missed the purpose of my question. There are some reasonably clear procedures available on the Debian website that cover the mechanics of downloading an image file, and burning that file to an SD card to install Debian on an RPi. My questions all have to do with what kind of GPIO support for the RPi is provided under Debian. Most of the documentation I found here was dated; i.e. out-of-date. And none of it addressed GPIO support.

[Aki]

Hello,

1. Raspbian has a "device tree", and this is used in the construction of a wide variety of "overlays" which expose both general and specialized GPIO functions. Does the Debian installation for Raspberry Pi have that device tree functionality and overlays available?

No, according to a previous discussion. I would suggest to install Raspbian (not Debian) if you need "device tree".

2. [..[ I see that Debian has the `libgpiod` package available. Is this package pre-installed in the Raspberry Pi images - or must it be installed after installation of the OS?

No, according to:

• Debian Raspberry Pi Maintainers Raspberry Pi image specs

There are some reasonably clear procedures available on the Debian website that cover the mechanics of downloading an image file, and burning that file to an SD card to install Debian on an RPi.

As side note to the topic, a quick search lead me here:

• Instructions to flash an image to an SD card

[seamusdemora]

Hello,

1. Raspbian has a "device tree", and this is used in the construction of a wide variety of "overlays" which expose both general and specialized GPIO functions. Does the Debian installation for Raspberry Pi have that device tree functionality and overlays available?

No, according to a previous discussion. Install Raspbian if you need them.

There are some reasonably clear procedures available on the Debian website that cover the mechanics of downloading an image file, and burning that file to an SD card to install Debian on an RPi.

As side note to the topic, a quick search lead me here:

• Instructions to flash an image to an SD card

That is all good information - Thank you! (Oh! note this thread that implies progress is being made toward DT/overlays/etc)

That just leaves my 2nd Question re libgpiod & GPIO support in general. Let me try re-phrasing that so it's clear:
a. Is libgpiod included in recent Debian Raspberry Pi images?
b. Does libgpiod "work" in recent releases/images? I've heard a report that it does not; that it's "installed but non-responsive". Maybe a switch/config to enable it?
c. Are there any other GPIO libraries (e.g. wiringPi) available under Debian on Raspberry Pi?

[Aki]

Hello,

a. Is libgpiod included in recent Debian Raspberry Pi images?

No, I suppose, according to:

• Debian Raspberry Pi - Maintainers Raspberry Pi image specs

You can check for yourself by downloading, flashing and viewing the contents of the image.

The package is available for download and installation from Debian repository (after the image is booted):

• https://packages.debian.org/bookworm/libgpiod2