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Wii Nunchuck + Arduino Mega + Model Railway = Fun

Well, it had to happen... I bought the header/adapter from here and then, after a little rewiring to fit the Arduino Mega, got the Wii Nunchuck reporting data to my Arduino. Note that this has been done already in multiple places:

• Motor shield and model train!
• Wii Nunchuk Controlled Model Train
• Dawson Station: Wii Nunchuck Train Control?

If you have an Arduino Mega, then make sure you have the Negative pin to GND, the Positive to 3.3v, the "d"/"data" pin to SDA20 and the "c"/"clock" pin to SCL 21.

You can then use this code to get the little train moving:

#include <Wire.h>
#include "nunchuck_funcs.h"
#define PWM_INPUT_PIN_1         2
#define PWM_INPUT_PIN_2         3
#define PWM_ENABLE_PIN_1        7
int throttle = 0;
int loop_cnt=0;
void setup() {
  Serial.begin(19200);
  nunchuck_setpowerpins();
  nunchuck_init(); // send the initilization handshake
}
void loop() {
  if( loop_cnt > 100 ) { // every 100 msecs get new data
    loop_cnt = 0;           
    nunchuck_get_data();
  }
  loop_cnt++;
  throttle = nunchuck_joyx() - 127;
  if (throttle < 10 && throttle > -10) throttle = 0;
  UpdateTrackPower();
}
void UpdateTrackPower() {
  if (throttle == 0) {
    digitalWrite(PWM_INPUT_PIN_1, LOW);
    digitalWrite(PWM_INPUT_PIN_2, LOW);
  } else {
    if (throttle > 0) {
      digitalWrite(PWM_INPUT_PIN_1, HIGH);
      digitalWrite(PWM_INPUT_PIN_2, LOW);
    } else if (throttle < 0) {
      digitalWrite(PWM_INPUT_PIN_1, LOW);
      digitalWrite(PWM_INPUT_PIN_2, HIGH);
    }
  }
  analogWrite(PWM_ENABLE_PIN_1, abs(throttle));
}

Note that you need to have the L298 Motor controller from the previous post connected to get power to tracks!

Now I just need to think of a cool way to use the buttons on this controller. Currently I just have the top joystick controlling the train on the X axis with center being stopped.