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Pinguino and Wii Nunchuck

This example shows how to connect a Pinguino board to the Wii Nunchuck.

For this test, we used an original Nunchuck from Nintendo. With compatible model, you need to adapt some value ( delay ).

The nunchuck can be used as a 3 axis accelerometer, an analog stick and 2 buttons.

The code uses the LibI2C module in Pinguino. We adapted the I2C initialisation to work with a clock frequency of 100 kHz. The output sends value to the serial port.

The beta 9-05 version is used to compile the code.

How to connect it ?

A piece of double-sided PCB has been used to make a male connector.


Pinguino is connected to the Nunchuck via the I2C bus.

SCL is PIN 0 and SDA is PIN 1.

The nunchuck is powered from the 5vcc Pinguino power supply.

Pinguino Breadboard


Two 22k resistors are used as pull-ups on the SDA and SCL lines.

Test is on a 18F2550 Pinguino but it can also be wired on a 18F4550.

The code

// test program for I2C communication with nunchuck
// Jean-Pierre MANDON 2011

#include <libI2C.c>

byte I2C_address=0x52;						// i2c address for nunchuck
unsigned char I2C_OK;						// acknowledge when calling I2C function
byte I2C_setParameters[2]={0x40,0x00};		                // nunchuck initialisation
byte I2C_readRegister[1]={0x00};			        // read instruction for nunchuck

void setup()
// Serial is used to monitor data
// special initialisation to set I2C to 100khz
i2c_open(I2C_MASTER, I2C_SLEW_OFF, 119);
// end of I2C initialisation

void nunchuck_init()
	I2C_OK=I2C_write(I2C_address,I2C_setParameters,2);	// set memory address for future read

void send_zero()
	I2C_OK=I2C_write(I2C_address,I2C_readRegister,1);	// set request to read

// prepare a new request to memory
void new_request()
unsigned char cpt;
	while ((cpt++<10)&&(!I2C_OK)) nunchuck_init();		
	while ((cpt++<10)&&(!I2C_OK)) send_zero();

void loop()
unsigned char i;

nunchuck_init();						// initialise nunchuck
if (!I2C_OK)
	Serial.printf("Init Error\n\r");
else Serial.printf("Init OK\n\r");
while ((i++<10)&&(!I2C_OK)) send_zero();			// prepare new request
if (!I2C_OK) 
        Serial.printf("Nunchuck Error\n\r");
else Serial.printf("Request OK\n\r");	
	I2C_OK = I2C_read(I2C_address,6);			// read nunchuck value
	if (I2C_OK)
		for (i=0;i<6;i++) Serial.printf("%d ",i2c_buffer[i]);
		new_request();					// prepare a new request

6 bytes are read from the nunchuck. Each byte is the value of a sensor.

byte 0 is the X analog value of the analog stick,
byte 1 is the Y analog value of the analog stick,

byte 2 is the X value of the 10 bit accelerometer (bits 2-9),
byte 3 is the Y value of the 10 bit accelerometer (bits 2-9),
byte 4 is the Z value of the 10 bit accelerometer (bits 2-9),

byte 5
bit 7-6 is bit 1-0 of the X accelerometer data,
bit 5-4 is bit 1-0 of the Y accelerometer data,
bit 3-2 is bit 1-0 of the Z accelerometer data,
bit 1 is the state of the C button ( 0=pressed ),
bit 0 is the state of the Z button ( 0=pressed ).

More about the nunchuck

WiiBrew website