By: Joe & Dan

    January 6th 2010
     
  We had decided to come up with a CPR training dummy that would show the user if they are doing the chest compressions the right way.  This could be done by using the Nunchuck from  a Wii gaming system and an arduino board.  The nunchuck is placed on the inside of the dummy and connected to the arduino through analog pins 5,4,3, and 2 as Inputs via an adapter found Here. 

The Library was found on the same website

The code that we are currently using is:

#include <Wire.h>
#include "nunchuck_funcs.h"

int an[] = {11,12,13,11,12,13,10,13,10,12,10,11,10,9,9,11,12,9,8,11,8,10,8,9,8,7,9,7,10,7,7,11,12,7,13,7};
int ca[] = {12,11,11,13,13,12,13,10,12,10,11,10,9,10,11,9,9,12,11,8,10,8,9,8,7,8,7,9,7,10,11,7,7,12,7,13};
int loop_cnt=0;
int t = 2500;

byte accx,accy,zbut,cbut;
int ledPin = 13;
int x=0;

void setup()
{
  for (int pin =7; pin<=13; pin++)
{
  pinMode(pin,INPUT); // Set as input
}
  
    Serial.begin(19200);
    nunchuck_setpowerpins();
    nunchuck_init(); // send the initilization handshake
   
    Serial.print("WiiChuckDemo ready\n");
}

void loop()
{
    if( loop_cnt > 100 ) { // every 100 msecs get new data
        loop_cnt = 0;

        nunchuck_get_data();

        accx  = nunchuck_accelx(); // ranges from approx 70 - 182
        accy  = nunchuck_accely(); // ranges from approx 65 - 173
        zbut = nunchuck_zbutton(); // show data everytime the Z button is pressed
        cbut = nunchuck_cbutton(); // show data everytime the C button is pressed
        x = nunchuck_accelx();        // sets variable x = nunchuck_accelx
        x= map(x,0,255,0,35);         // sets variable x = map(x,0,255,0,35)
       delayMicroseconds(t);          // sets delay to variable (t)
        pinMode (an[x], OUTPUT); // declares an[x] as an OUTPUT
        pinMode (ca[x], OUTPUT); // declares ca[x] as an OUTPUT
        digitalWrite(an[x], HIGH);    // set an[x] to HIGH
        digitalWrite(ca[x], LOW);     // set ca[x] to LOW
        delayMicroseconds(t);        // sets delay to variable (t)
        digitalWrite(an[x], LOW);    // sets an[x] to LOW
        digitalWrite(ca[x], LOW);    // sets an[x] to LOW
        delayMicroseconds(t);       // shows variable (t) for delay
        pinMode (an[x], INPUT);   // sets an[x] as an INPUT
        pinMode (ca[x], INPUT);   // sets ca[x] as an INPUT
        Serial.print("accx: "); Serial.print((byte)accx,DEC);
        Serial.print("\taccy: "); Serial.print((byte)accy,DEC);
        Serial.print("\tzbut: "); Serial.print((byte)zbut,DEC);
        Serial.print("\tcbut: "); Serial.println((byte)cbut,DEC);
    }
    loop_cnt++;
    delay(1);
}

Conversions for the serial monitor:
  +1g = 180
   -1g = 72
    0g = 128
    -2g = 0
    +2g = 255
This is a calculation of the amount of G's that are being experienced.
So when it's not moving, the normal force = the force of gravity which is 0g (not moving).
    y = 63.75x + 128