• Product page: https://libre.computer/products/aml-s905x-cc/
• Pin definitions: https://docs.google.com/spreadsheets/d/1U3z0Gb8HUEfCIMkvqzmhMpJfzRqjPXq7mFLC-hvbKlE/edit#gid=0
• Schematic: s905x_6l_170707_v1_0.pdf
• S905X Datasheet: s905x_datasheet_v0.3-20170314-wesion.pdf (There is almost certainly a newer version, but this is the one I see the most floating around on the web)

The UART on the 40pin GPIO header (pins 8 and 10) is not enabled by default. It must be enabled by enabling a device tree overlay that is included with libretech-wiring-tool.

1. Clone, build, and install the libretech-wiring-tool
2. Enable the DTO for UART-A

   sudo ldto enable uart-a

3. Check dmesg

   c11084c0.serial: ttyAML6 at MMIO 0xc11084c0 (irq = 49, base_baud = 1500000) is a meson_uart

4. Test with minicom or whatever
5. To persist after reboot, merge:

   sudo ldto merge uart-a

Specifically, SDA and SCL pins on GPIOs 3 & 4.

1. Clone, build, and install the libretech-wiring-tool as above