====== Libre Computing AML-S905X-CC ======
===== Resources =====
  * 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)
===== Notes =====
==== Enable UART-A ====
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 [[https://github.com/libre-computer-project/libretech-wiring-tool|libretech-wiring-tool]]. 

  - Clone, build, and install the libretech-wiring-tool
  - Enable the DTO for UART-A ''sudo ldto enable uart-a''
  - Check dmesg ''c11084c0.serial: ttyAML6 at MMIO 0xc11084c0 (irq = 49, base_baud = 1500000) is a meson_uart''
  - Test with ''minicom'' or whatever
  - To persist after reboot, merge: ''sudo ldto merge uart-a''

Somewhat confusingly, both ''uart-a'' and ''uarta'' exist as device tree overlays. ''uarta'' maps to ''uart-a-rts-cts'' which uses pins 16 and 18 for hardware flow control.
==== Enable i2c and the DS3231 ====
Specifically, SDA and SCL pins on GPIOs 3 & 4.

  - Clone, build, and install the libretech-wiring-tool as above
  - Install i2c tools: ''sudo apt install i2c-tools''
  - Enable the i2c-ao DTO: ''sudo ldto enable i2c-ao''
  - Check for your devices: ''i2cdetect -y 1'' (DS3231 should be at 0x68)
  - Enable for DS3231 on i2c-ao: ''sudo ldto enable i2c-ao-ds3231''
  - Check dmesg: <code>[ 4024.485534] rtc-ds1307 1-0068: SET TIME!
[ 4024.488196] rtc-ds1307 1-0068: registered as rtc0
[ 4024.489394] rtc-ds1307 1-0068: setting system clock to 2000-01-01T01:07:25 UTC (946688845)</code>
  - Merge to save: ''sudo ldto merge i2c-ao ; sudo ldto merge i2c-ao-ds3231''