using GPIOs

[sebba]

Hello,

I am curious if there is some "standardization" for using GPIO pins.
I mean, what GPIO is used/recommended/preferred for various signals like 1wire, seatalk, shutdown and so on

I am trying to develop some kind of hat and I want to do that without conflicting with other hats, like MacArthur.
By example, MacArthur hat is using GPIO20 for seatalk_rx, GPIO21 for shutdown, GPIO26 for power_off and GPIO19 for 1wire.

Other "serious" hardware devices are sticking on same pins?

Also, maybe we can try to do a list with the most used signals and their GPIOs pins. I hope will be useful for hardware design.

Fair wind,
Seb

[Sailoog]

https://pinout.xyz/

https://github.com/raspberrypi/firmware/...ays/README

[sebba]

thanks, but this is not what I asked...

[holgerw]

hi sebba

there are no standard for HATs, some bring even an dedicated rom filled with software...

you have to check you system which ports are used if you build your own hardware.

better go for the i2C and onewire as these are neatly bus systems and with them are many
devices possible at the same time without much effort.

[sebba]

got it, thank you

[Adrian]

The MacArthur HAT is probably on the extreme end in number of GPIOs used. So if your HAT works with that, it's probably going to play with most other HATs too.

The only additional pins to avoid are 27 (GPIO0) and 28 (GPIO1). These pins are reserved for an I2C EEPROM to store configuration info for the Pi.

As Holger wrote, there is no hard standard. But ignoring MacArthur, most HATs are connecting through UART0, SPI0, or I2C1. A trick to work around unexpected conflicts is to add a jumper on the trace connecting to the Pi GPIO, either as a solder jumper, or as a pin header like we use for the CAN termination. That way it's easy to rewire the connection if needed.

[Techstyle]

The MacArthur HAT is probably on the extreme end in number of GPIOs used. So if your HAT works with that, it's probably going to play with most other HATs too.

The only additional pins to avoid are 27 (GPIO0) and 28 (GPIO1). These pins are reserved for an I2C EEPROM to store configuration info for the Pi.

As Holger wrote, there is no hard standard. But ignoring MacArthur, most HATs are connecting through UART0, SPI0, or I2C1. A trick to work around unexpected conflicts is to add a jumper on the trace connecting to the Pi GPIO, either as a solder jumper, or as a pin header like we use for the CAN termination. That way it's easy to rewire the connection if needed.

I would also check the GPIO usage of PiCAN-M Hat, Sailor Hat and any of the Waveshare CAN Hats and stay away from those as well

[sebba]

Good information, @Adrian and @Techstyle, thank you both!