This allows an AVR with native USB support to mimick a wired Switch controller. A different device tells the AVR what buttons/joysticks to press over UART. It uses a default baud of 115200, but this can be edited in the makefile.
This can be used to easily make a custom controller using any computer. A desktop can talk to it through a UART adapter, an Arduino Uno can be used as a custom controller (see the arduino_library folder), etc.
A way to easily flash devices with a DFU bootloader can be found in the flash_helper/ folder.
Commands are purely used for button presses. A 4-bit address is sent alongside the 8-bit corresponding value, split between two 8-bit packets. It is sent like so: aaaavvvv 0000vvvv
Where aaaa is the 4-bit address , and vvvv vvvv is the 8-bit value to be written to that address, split in half. 0000 is required.
So say you want to set the left joystick y-axis to 0x3C. The address 0x05 = 0b0101, the value is 0x3C = 0b00111100. The first byte is the address shifted right by 4 and the upper 4 bits of the value downshifted, so 0b01010011. The second byte is the lower 4 bits of the value, so 0b00001100. 0b01010011 0b00001100 = 0x53 0x0C.
There are a few other UART Switch projects out there with more human-readable command set, but this is very efficient and easy to program.
| Address | Name | Description | Unpressed Value |
|---|---|---|---|
| 01h | BTN_0 | Buttons such as Minus, Home, and Capture. | 00h |
| 02h | BTN_1 | Buttons such as A, B, and X. | 00h |
| 03h | HAT | Directional pad. | 08h |
| 04h | LX | Left joystick x-axis. | 80h |
| 05h | LY | Left joystick y-axis. | 80h |
| 06h | RX | Right joystick x-axis. | 80h |
| 07h | RY | Right joystick y-axis. | 80h |
Presses or releases the button. 0 is release, 1 is press.
| Bit | Button |
|---|---|
| 7:6 | [reserved] |
| 5 | CAPTURE |
| 4 | HOME |
| 3 | RCLICK |
| 2 | LCLICK |
| 1 | PLUS |
| 0 | MINUS |
Presses or releases the button. 0 is release, 1 is press.
| Bit | Button |
|---|---|
| 7 | ZR |
| 6 | ZL |
| 5 | R |
| 4 | L |
| 3 | X |
| 2 | A |
| 1 | B |
| 0 | Y |
Control the Directional Pad (d-pad).
| Value | Direction |
|---|---|
| 00h | Up |
| 01h | Up-Right |
| 02h | Right |
| 03h | Down-Right |
| 04h | Down |
| 05h | Down-Left |
| 06h | Left |
| 07h | Up-Left |
| 08h | Neutral |
Registers 03h through 06h control the joysticks. 00h corresponds to completely left/down, 80h is neutral, and FFh is completely right/up.