docs: add hat hardware information

docs/hat_hardware.md

@@ -0,0 +1,45 @@
+# PlanktoScope Hat Hardware
+
+## Buses and GPIO pinout
+
+### I2C1 Bus
+#### RTC RV-3028-C7
+Address 0x52
+Configured through a kernel driver.
+
+#### OLED Display
+Address 0x3c
+
+### SPI0 Bus
+#### Motor Controller 0: TMC5160
+Chip Enable: SPI0_CE0
+Motor Enable: GPIO23
+
+Diagnostic output:
+GPIO16 for Error output
+GPIO20 for Stall output
+
+
+#### Motor Controller 1: TMC5160
+Chip Enable: SPI0_CE1
+Motor Enable: GPIO5
+
+Diagnostic output:
+GPIO16 for Error output
+GPIO20 for Stall output
+
+### GPIO
+#### Fan control
+PWM1 control through GPIO13
+
+#### LED0 control
+PWM0 control through GPIO18
+
+#### LED1 control
+PWM0 control through GPIO12
+
+
+### I2C0 Bus
+#### EEPROM M24C32
+Address 0x50
+For HAT information only.

mkdocs.yml

@@ -9,6 +9,8 @@ nav:
     - Usage:
         - User Interface: ui_guide.md
         - Collection devices: collection_devices.md
+    - Hardware:
+        - Planktoscope HAT: hat_hardware.md
     - Under the hood:
         - Software architecture: software_architecture.md
         - MQTT Messages: mqtt_messages.md