Extend RF Unit documentation

docs/rf-unit.md

@@ -3,24 +3,124 @@
 ## Info
 
 ### Xbox One (PHAT)
+
 Part Number: X867281-005
+Codename: Lithium
 
 Components:
+
 - Infrared Receiver (U1)
 - Soundchip - ISD9160F (U4)
 - Connector to sound speaker (J1)
 - Wifi Antenna connector (J2)
 - FPC connector (J3)
 - Motherboard connector (J8)
 
-#### Flashing the soundchip
+####  General
+
+The RF Unit, compared to Xbox 360, is very simple. It does not contain any RF hardware onboard.
+It only contains an IR Receiver, the Nuvoton Soundcorder Chip (which also handles button presses from the front panel touch buttons) and an internal antenna.
+Actual RF communication is happening via [Wifi module](wifi.md).
+
+Communication from the Nuvotun chip to the Southbridge is done via I2C.
+
+#### Pinout
+
+Connector
+
+| Pin| Function        |
+|----|-----------------|
+|  1 | LED Nexus       |
+|  2 | LED Halo        |
+|  3 | LED Zone        |
+|  4 | 5V (VCC)        |
+|  5 | I2C CLK         |
+|  6 | I2C DATA        |
+|  7 | IR Data         |
+|  8 | PWR Switch (N)  |
+|  9 | GND             |
+| 10 | EJECT Switch (N)|
+| 11 | INT_N           |
+| 12 | 3,3V STDBY      |
+| 13 | BIND Switch (N) |
+| 14 | GND             |
+| 15 | -               |
+| 16 | -               |
+| 17 | -               |
+| 18 | GND             |
+| 19 | GND             |
+
+#### Nuvoton Soundcorder chip
+
+Model: ISD9160F
+
+I2C address: `0x5A`
+
+Datasheet: [ISD9160FI](./rf-unit/1811151450_Nuvoton-Tech-ISD9160FI_C79806.pdf)
+
+#### Communication
+
+The exact communication protocol is unknown so far.
+
+Two sample implementations how the chip *could* be programmed.
+
 - [Trumpet project](https://github.com/robbie-cao/trumpet) on github
 - [Piccolo project](https://github.com/robbie-cao/piccolo) on github
 
 ### Xbox One S
 
+Codename: Sodium
+
+#### Pinout
+
+Connector
+
+| Pin| Function        |
+|----|-----------------|
+|  1 | LED Nexus       |
+|  2 | -               |
+|  3 | IR Blaster      |
+|  4 | PWR Switch (N)  |
+|  5 | EJECT Switch (N)|
+|  6 | INT_N           |
+|  7 | 3,3V STDBY      |
+|  8 | 5V              |
+|  9 | ACC_RESET       |
+| 10 | IR (RX)         |
+| 11 | GND             |
+| 12 | USB2 (-)        |
+| 13 | USB2 (+)        |
+| 14 | GND             |
+| 15 | I2C CLK         |
+| 16 | I2C DATA        |
+
 ### Xbox One X
 
+Codename: Cactus
+
+**NOTE**: Front panel on Xbox One X does not use I2C anymore.
+
+#### Pinout
+
+| Pin| Function        |
+|----|-----------------|
+|  1 | IR (RX)         |
+|  2 | EJECT Switch (N)|
+|  3 | -               |
+|  4 | IR Blaster      |
+|  5 | ACC_RESET       |
+|  6 | GND             |
+|  7 | USB2 (-)        |
+|  8 | USB2 (+)        |
+|  9 | 3,3V STDBY      |
+| 10 | GND             |
+| 11 | -               |
+| 12 | -               |
+| 13 | -               |
+| 14 | PWR Switch (N)  |
+| 15 | LED Nexus       |
+| 16 | 5V              |
+
 ## Pictures
 Xbox One (PHAT)