MAD Burster Arduino.pde

// Rubisync Sensor Interface for Arduino 0018 (MAD Burster)
// Copyright 2010 Glenn Powers <glennpowers@gmail.com>
// http://meaning.com/wiki/Rubisync

// This program is free software; you can redistribute it and/or modify
// it under the terms of the GNU General Public License as published by
// the Free Software Foundation; version 3 of the License.

// This program is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
// GNU General Public License for more details.

// includes micromag 3-axis magnetic field sensor reading code from:
// http://wiring.org.co/learning/basics/magneticfield.html
            
// Pin Assignments                       
int SCLK  = 6;  // magnetometer pin 1
int MISO  = 5;  // magnetometer pin 2
int MOSI  = 4;  // magnetometer pin 3
int SSNOT = 9;   // magnetometer pin 4
int DRDY  = 8;   // magnetometer pin 5
int RESET = 7;   // magnetometer pin 6

// variables to store sensor data
int magXval;
int magYval;
int magZval;

int x;
int y;
int z;

unsigned long magXtime;
unsigned long magYtime;
unsigned long magZtime;


void setup()
{
  //analogReference(INTERNAL); // ser ADC voltage ref to 3.3 internal
  Serial.begin(115200);          //  setup serial  
  pinMode(SSNOT, OUTPUT);
  pinMode(RESET, OUTPUT);
  pinMode(MOSI, OUTPUT);
  pinMode(SCLK, OUTPUT);
  pinMode(MISO, INPUT);
  pinMode(DRDY, INPUT);
  digitalWrite(SSNOT, LOW);
}


void loop()
{
  magXval = readAxis(1);  // read the y-axis magnetic field value
  magXtime = micros();    // microseconds since program began, ~70 min epoch
  
  Serial.print("1,");     // Sensor Name
  Serial.print(magXval);  // Sensor Value
  Serial.print(",");       // separator
  Serial.print(magXtime); // time
  Serial.println("");      // print carriage return
  
  magYval = readAxis(2);  // read the y-axis magnetic field value
  magYtime = micros();    // microseconds since program began, ~70 min epoch
    
  Serial.print("2,");     // Sensor Name
  Serial.print(magYval);  // Sensor Value
  Serial.print(",");       // separator
  Serial.print(magYtime); // time
  Serial.println("");      // print carriage return
  
  magZval = readAxis(3);  // read the z-axis magnetic field value
  magZtime = micros();    // microseconds since program began, ~70 min epoch

  Serial.print("3,");     // Sensor Name
  Serial.print(magZval);  // Sensor Value
  Serial.print(",");       // separator
  Serial.print(magZtime); // time
  Serial .println("");      // print carriage return

}


// specific commands for the magnetic sensor

void sendBit(int bit){
  // send the bit on the RISING edge of the clock
  digitalWrite(MOSI, bit);
  delayMicroseconds(2);
  digitalWrite(SCLK, HIGH);
  delayMicroseconds(2);
  digitalWrite(SCLK, LOW);
  delayMicroseconds(2);
}

int receiveBit(){
  // receive the data on the FALLING edge of the clock
  digitalWrite(SCLK, HIGH);
  delayMicroseconds(2);
  int bit = digitalRead(MISO);
  delayMicroseconds(2);
  digitalWrite(SCLK, LOW);
  delayMicroseconds(2);
  return bit;
}

float readAxis(int axis){
  // send eight bits, wait until the data is ready then receive 16 bits
  
  // pulse the reset
  digitalWrite(RESET, LOW);
  delayMicroseconds(2);
  digitalWrite(RESET, HIGH);
  delayMicroseconds(2);
  digitalWrite(RESET, LOW);
  delayMicroseconds(2);

  // send the command byte
  // set the time to read the magnetic sensors (ASIC period) as /2048
  sendBit(LOW);
  sendBit(HIGH);
  sendBit(HIGH);
  sendBit(LOW);
  sendBit(LOW);
  sendBit(LOW);

  // the last two bits select the axis
  if (axis == 0){ // x axis
    sendBit(LOW);
    sendBit(HIGH);
  }
  else if (axis == 1){ // y axis
    sendBit(HIGH);
    sendBit(LOW);
  }
  else{ // z axis
    sendBit(HIGH);
    sendBit(HIGH);
  }

  // wait until the DRDY line is high
  while(digitalRead(DRDY) == LOW) {
  }

  long total = 0;

  // receive result 
  // the leftmost bit mark the number as positive or negative
  long sign = receiveBit();

  // the remaining bits are converted to an integer
  for (int i = 14; i >= 0; i = i - 1){
    long thisbit = receiveBit();
    thisbit = thisbit << i;
    total = total | thisbit;
  }

  if(sign == 1) {
    total = total - 32768;
  }
  
  // set and return the appropriate variable
  if (axis == 0){
    x = total;
  }
  else if (axis == 1){
    y = total;
  }
  else{
    z = total;
  }
  return total;
}

 
void error(char *str)
{;
  Serial.print("error: ");
  Serial.println(str);
}