ExtFriend is a USB adapter for the WonderSwan's EXT port based on the RP2040 chip and the Raspberry Pi Pico board, providing the following features at a low cost:
- A USB serial port communicating with the WonderSwan at 9600 and 38400 baud,
- A USB audio device allowing digital stereo audio capture from the WonderSwan.
Both features can be active simultaneously - for example, this could allow one to control a WonderSwan as an audio synthesizer.
Special thanks to BluRaf for providing support and advice through my first journey into TinyUSB lands.
- If you mute the USB audio device, the WonderSwan will consider the headphones as disconnected, re-enabling the internal speaker.
You need to set your USB device's serial port to COM1-COM7 for compatibility with TransMagic. See this article for more information.
# Install Source Han Sans font, alias it to Microsoft Japanese fonts
$ winetricks sourcehansans fakejapanese
# Connect USB ExtFriend device to Wine virtual COM1 port
$ ln -s /dev/ttyACM0 ~/.wine/dosdevices/com1
# Run TransMagic
$ LANG=ja_JP.UTF-8 wine TransMagic.exe
- Copy
pico_sdk_import.cmakefrom your Pico-SDK installation to the repository's root.- For example,
cp /usr/share/pico-sdk/external/pico_sdk_import.cmake .
- For example,
- Run
mkdir build,cd build,cmake ..,make. - To flash onto an RP2040,
picotool load extfriend.uf2.
- Flash the program to the Pico: for example,
picotool load -v -x extfriend.uf2 - Connect the Raspberry Pi Pico to the WonderSwan's EXT port. The default build of ExtFriend uses seven consecutive Pi Pico pins, as follows:
- EXT GND - Pico GND (for example pin 3)
- EXT SER_MOSI - Pico pin 2 (GP1)
- EXT SER_MISO - Pico pin 1 (GP0)
- If you want to use digital audio capture:
- EXT HDPN_BCLK - Pico pin 7 (GP5)
- EXT HDPN_LRCK - Pico pin 6 (GP4)
- EXT HDPN_SDAT - Pico pin 5 (GP3)
- EXT /HDPN_DETECT - Pico pin 4 (GP2)
If you don't have an EXT port plug or cable handy, you can use an HDMI breakout board. An example instruction guide is provided here (in Japanese), for a $2 AliExpress board.
GPLv3+.