libjoybus

An implementation of the Joybus protocol used by N64 and GameCube controllers, for 32-bit microcontrollers.

Supported Platforms

The following platforms are currently supported:

• Raspberry Pi RP2040 and RP2350 series MCUs
• Silicon Labs EFR32 Series 1 and Series 2 MCUs

Communicating with Controllers

In host mode, libjoybus allows a microcontroller to communicate with N64 and GameCube controllers. This allows you to use input data from N64 and GameCube controllers in your projects.

#include <joybus/joybus.h>
#include <joybus/host/gamecube.h>
 
struct joybus_rp2xxx rp2xxx_bus;
struct joybus *bus = JOYBUS(&rp2xxx_bus);
 
struct joybus_gc_controller_input input;
uint8_t joybus_buffer[JOYBUS_BLOCK_SIZE];
 
void poll_cb(struct joybus *bus, int result, void *user_data) {
  // Check for errors
  // TODO
 
  // Unpack the input data from the response
  joybus_gcn_unpack_input(&input, joybus_buffer, JOYBUS_GCN_ANALOG_MODE_3);
 
  // Do something with the input data
  if(input.buttons & JOYBUS_GCN_BUTTON_A) {
    // The A button is pressed
  }
}
 
void main() {
  // Initialize the Joybus
  joybus_rp2xxx_init(&rp2xxx_bus, MY_GPIO, pio0);
  joybus_enable(bus);
 
  while (1) {
    // Read a GameCube controller in analog mode 3 with the rumble motor off
    joybus_gcn_read(bus, JOYBUS_GCN_ANALOG_MODE_3, JOYBUS_GCN_MOTOR_STOP, joybus_buffer,
                    poll_cb, NULL);
 
    sleep_ms(10);
  }
}

Emulating a Controller

In target mode, libjoybus allows a microcontroller to act as an N64 or GameCube controller. This allows you to create custom controllers that can interface with N64, GameCube, and Wii consoles.

#include <joybus/joybus.h>
#include <joybus/target/gc_controller.h>
 
struct joybus_rp2xxx rp2xxx_bus;
struct joybus *bus = JOYBUS(&rp2xxx_bus);
struct joybus_gc_controller controller;
 
void main() {
  // Initialize the Joybus
  joybus_rp2xxx_init(&rp2xxx_bus, MY_GPIO, pio0);
  joybus_enable(bus);
 
  // Initialize a GameCube controller target
  joybus_gc_controller_init(&controller, JOYBUS_GAMECUBE_CONTROLLER);
 
  // Register the target on the bus
  joybus_target_register(bus, JOYBUS_TARGET(&controller));
 
  // At this point the target will respond to commands from a connected console!
  // Modify the input state as needed, for example based on GPIO or ADC readings
  while (1) {
    // Clear previous button state
    controller.input.buttons &= ~JOYBUS_GCN_BUTTON_MASK;
 
    // Simulate pressing the A button
    controller.input.buttons |= JOYBUS_GCN_BUTTON_A;
 
    // Simulate setting the analog stick position
    controller.input.stick_x = 200;
    controller.input.stick_y = 200;
 
    sleep_ms(10);
  }
}