Raspberry Pi Impersonates Nintendo Switch Controller

Adapt various USB gamepads, flight control sticks, and fight sticks for use with the Nintendo Switch (NS) console. All controllers are active but are seen by the console as one controller so co-pilot mode is always active.

                  Buttons
                     |
                     v
USB Controllers -> Raspberry Pi -> NSGadget -> Nintendo Switch
                     ^
                     |
                  Buttons

See README_pinball.md for more details on this test configuration.

See README_fs17.md for a custom Farming Simulator controller using a MIDI keyboard.

See README_gpio.md for a GPIO break out board.

See README_voice.md for adding a voice assistant. The Speech-To-Text engine Deep Speech works offline so no Internet connection is needed. This also eliminates privacy concerns with a live microphone. The audio is never sent outside the Raspberry Pi. Deep Speech needs a fast CPU so a Raspberry Pi 4 is best. A Pi 3+ is about half as fast so the delays are noticeable.

USB Controllers

The following USB controllers are supported. The drivers are all included so nothing needs to be installed.

• Hori HoriPad Nintendo Switch compatible gamepad
• Microsoft Xbox One gamepad
• Sony PS4 DS gamepad
• Logitech Extreme 3D Pro flight control stick
• Thrustmaster T.16000M flight control stick
• Dragon Rise arcade fight stick/joystick

jstest-gtk is a very handy utility to understand controller axes and buttons numbering. This is essential to map axes and buttons to the NS controller.

sudo apt install jstest-gtk

USB NSGadget

NSGadget is an Adafruit Trinket M0 emulating an NS compatible gamepad. The UART connection between the Pi and NSGadget runs at 2 Mbits/sec. The UART device name is /dev/ttyAMA0.

Trinket M0	Raspberry Pi
BAT	5V0
Gnd	Gnd
TX(4)	D14(RXD)
RX(3)	D15(TXD)

The firmware/ directory has the firmware.

Compiled programs can be burned into the Trinket M0 just by dragging and dropping a UF2 file on to the Trinket M0 USB drive. There is no need to install the Arduino IDE, source code, or USB serial device driver.

• Download the UF2 file of your choice.
• Plug in the Trinket M0 to the computer.
• Double tap the Trinket M0 reset button.
• When the TRINKETBOOT USB drive appears, drop the UF2 file on to the drive.
• Wait a few seconds until the Trinket M0 reboots.

Prepare the Pi

Install Raspbian Buster Lite or Desktop. Update to the latest version.

sudo apt update
sudo apt full-upgrade
sudo reboot

Prepare /dev/ttyAMA0

If the Pi has built-in Bluetooth (Pi 3, Pi 3+, Pi 4, Pi zero W) disable Bluetooth to free up the PL011 UART.

The following is from /boot/overlays/README.

Name:   disable-bt
Info:   Disable onboard Bluetooth on Pi 3B, 3B+, 3A+, 4B and Zero W, restoring
        UART0/ttyAMA0 over GPIOs 14 & 15.
        N.B. To disable the systemd service that initialises the modem so it
        doesn't use the UART, use 'sudo systemctl disable hciuart'.
Load:   dtoverlay=disable-bt

sudo systemctl disable hciuart
sudo nano /boot/config.txt

Add dtoverlay=disable-bt as the last line of config.txt. Save and exit.

Turn off the login shell on /dev/ttyAMA0. This is necessary even if the Pi does not have Bluetooth.

sudo raspi-config

• Select Interfacing Options.
• Select P6 Serial.
• Disable the login shell.
• Enable the serial interface.
• Exit raspi-config

sudo reboot

Software

The Python3 program nsac.py holds all the parts together. Once it opens the UART, it spins up a thread for each USB controller and a thread to monitor the buttons connected to GPIO pins.

sudo apt install python3 python3-pip python3-serial python3-gpiozero python3-mido
git clone https://github.com/gdsports/NSGadget_Pi
cd NSGadget_Pi
./nsac.py

nsgpadserial.py provides an interface to the NS Gadget device.

Appliance Mode

If you do not want to login to run nsac.py and are not interested in changing it, try appliance mode. In appliance mode, nsac.py runs on power up. Also the file system is set for read-only mode so powering off without shutting down should not corrupt the microSD card.

Automatically run nsac.py

crontab -e

Add the following line to the end of the file. The small shell script starts nsac.py at power/restart in a loop (just in case it crashes).

@reboot              nohup /home/pi/NSGadget_Pi/nsac.sh >/dev/null 2>&1 &

Enable read-only file system to prevent microSD card corruption

sudo raspi-config

• Select 7 Advanced Options.
• Select AB Overlay FS to enable overlay file system (read-only) and write-protect boot partition.
• Exit and reboot