esp32-wii-nunchuk

This is a library to use the Wii Nunchuk with the ESP32 via I2C. It can be used both with the Arduino IDE or with code using the ESP-IDF directly. To use the library in your Arduino IDE sketch, just copy the files wii_i2c.c and wii_i2c.h to your sketch directory.

This library uses the ESP-IDF I2C API because the Arduino Wire library doesn't work reliably in the ESP32 with Wii controllers.

This library supports the Wii Nunchuk and the Wii Classic Controller. It shouldn't be hard to adapt it to work with other I2C devices that plug in the Wiimote (like the Classic Controller Pro, Wii Motion Plus, etc.) with the information available in the Wiibrew project, but I have none of these devices so I don't know for sure.

Coexisting with Arduino Wire Library

The Arduino Wire Library for the ESP32 (from Wire.h) uses I2C port 0 for the Wire object, and port 1 for the Wire1 object. So don't use Wire if using I2C port 0 with this library, and don't use Wire1 if using I2C port 1.

Example Code

Here's a simple example using the Wii Nunchuk. For a more complete example that detects and handles multiple controller types, see esp32-wii-nunchuk.ino.

#include "wii_i2c.h"

// pins connected to the Nunchuk:
#define PIN_SDA 32
#define PIN_SCL 33

// ESP32 I2C port (0 or 1):
#define WII_I2C_PORT 0

void setup()
{
  Serial.begin(115200);

  if (wii_i2c_init(WII_I2C_PORT, PIN_SDA, PIN_SCL) != 0) {
    Serial.printf("Error initializing nunchuk :(");
    return;
  }
  wii_i2c_request_state();
}

void loop()
{
  const unsigned char *data = wii_i2c_read_state();
  wii_i2c_request_state();
  if (! data) {
    Serial.printf("no data available :(")
  } else {
    wii_i2c_nunchuk_state state;
    wii_i2c_decode_nunchuk(data, &state);
    Serial.printf("Stick position: (%d,%d)\n", state.x, state.y);
    Serial.printf("C button is %s\n", (state.c) ? "pressed" : "not pressed");
    Serial.printf("Z button is %s\n", (state.z) ? "pressed" : "not pressed");
  }
  delay(1000);
}

Multi-Core Support

If you have time-sensitive code that can't wait for the controller to respond, use the API function that spawns a task that reads the controller state in a different core. For example:

#include "wii_i2c.h"

// pins connected to the controller:
#define PIN_SDA 32
#define PIN_SCL 33

// ESP32 I2C port (0 or 1):
#define WII_I2C_PORT 0

// CPU id where the task will run (1=the core
// where your code usually runs, 0=the other core):
#define READ_TASK_CPU 0

// delay in milliseconds between controller reads:
#define READ_DELAY 30

static unsigned int controller_type;

void setup()
{
  Serial.begin(115200);

  if (wii_i2c_init(WII_I2C_PORT, PIN_SDA, PIN_SCL) != 0) {
    Serial.printf("Error initializing nunchuk :(");
    return;
  }

  // if you want to read the controller identity,
  // do it BEFORE starting the read task:
  const unsigned char *ident = wii_i2c_read_ident();
  controller_type = wii_i2c_decode_ident(ident);

  // start the a task that reads the controller state in a different CPU:
  if (wii_i2c_start_read_task(READ_TASK_CPU, READ_DELAY) != 0) {
    Serial.printf("Error creating task to read controller state");
    return;
  }
}

void loop()
{
  // this function always returns quickly, either
  // with new data or NULL if data isn't ready:
  const unsigned char *data = wii_i2c_read_data_from_task();
  if (data) {
     // decode data according to controller_type:
     //   wii_i2c_decode_nunchuk(data, &nunchuk_state);
     //   wii_i2c_decode_classic(data, &classic_state);
  }
  
  // do other timing-sensitive stuff
}