# Alternate pre-populated device trees:
Each folder contains a `.dts` file and a README showing the GPIO pin mappings.

Copy the desired '.dts' file to the [build-trees](../build-trees) folder and follow the readme there to build the device-tree binaries.

There are instructions at the end of that document on how you can use a custom 'dtb' and make it permanent across reboots and kernel upgrades.

The issue with using these trees is that **if** the upstream device tree or includes is modified you need to manually rebuild these trees, and any changes to the upstream <FIX THIS: WHICH IS THE SOURCE??> file need to be detected and applied too.
- Fortunately this should not be an issue in practice; the kernel *should* remain very stable going forward. Ubuntu 24.04.1 is a LTS release..

The authors personal advice is to use this only if needed; or as a learning excercise.

## Common
[The common (generic) device tree I will use in my project, suitable for many occasions](./common)
* Has 2x UART (plus the console uart), 2x I2C. 1xSPI
* 12 unassigned GPIO pins

## Serial
[Four UART interfaces *and* Four I2C interfaces](./serial)
* Has 4x UART (plus the console uart), 4x I2C
* UART3 has RTC/CTS pins available too
* 10 unassigned GPIO pins

## SPI
[SPI plus Serial interfaces](./spi)
* Has 3x UART (plus the console uart), 3x I2C. 1xSPI
* 8 unassigned GPIO pins