// digipot

#define DATAOUT 11//MOSI
#define DATAIN 12//MISO - not used, but part of builtin SPI
#define SPICLOCK  13//sck
#define SLAVESELECT 10//ss

byte pot=0;
byte resistance=0;



//Accelerometer Sensor
//Matt @ http://antipastohw.blogspot.com/
//Author of original code base: Marcos Yarza, Malmo University - Sweden, http://www.0j0.org

//Pin definitions
#define xaccPin 8
#define yaccPin 7

//Global variables
long xacc = 0;
long yacc = 0;


int x = 0;
int y = 0;

int a = 0;
int b = 0;
int c = 0;
int d = 0;



// digipot functions

char spi_transfer(volatile char data)
{
  SPDR = data;                    // Start the transmission
  while (!(SPSR & (1<<SPIF)))     // Wait the end of the transmission
  {
  };
  return SPDR;                    // return the received byte
}


byte write_pot(int address, int value)
{
  digitalWrite(SLAVESELECT,LOW);
  //2 byte opcode
  spi_transfer(address);
  spi_transfer(value);
  digitalWrite(SLAVESELECT,HIGH); //release chip, signal end transfer
}

void setup()
{
  byte i;
  byte clr;
  pinMode(DATAOUT, OUTPUT);
  pinMode(DATAIN, INPUT);
  pinMode(SPICLOCK,OUTPUT);
  pinMode(SLAVESELECT,OUTPUT);
  digitalWrite(SLAVESELECT,HIGH); //disable device
  // SPCR = 01010000
  //interrupt disabled,spi enabled,msb 1st,master,clk low when idle,
  //sample on leading edge of clk,system clock/4 (fastest)
  SPCR = (1<<SPE)|(1<<MSTR);
  clr=SPSR;
  clr=SPDR;
  delay(10);
  for (i=0;i<6;i++)
  {
    write_pot(i,255);
  }


  //Serial.begin(9600); // Sets the baud rate to 9600
  pinMode(xaccPin, INPUT);
  pinMode(yaccPin, INPUT);

}



long readAcceleration(int axe){
  int count = 0;
  long accel = 0;
  int value = 0;

  value = digitalRead(axe);
  while(value == HIGH) { // Loop until pin reads a low
    value = digitalRead(axe);
  }

  while(value == LOW) { // Loop until pin reads a high
    value = digitalRead(axe);
  }

  while(value == HIGH) { // Loop until pin reads a low and count
    value = digitalRead(axe);
    count = count + 1;
  }

  //accel = abs(8 * (count * 18 / 10 - 500)); //this was the original function
  accel = count;

  return accel;
}





void loop() {
  //Grab the accelerometer readings:
  xacc = readAcceleration(xaccPin); //reads and represents acceleration X
  yacc = readAcceleration(yaccPin); //reads and represents acceleration Y

  //Print the output to the serial port:
  
  /*
  Serial.print("X:");
  Serial.print(xacc);
  Serial.print(" Y:");
  Serial.print(yacc);
  Serial.print("\n\r");
*/

  // x = ((xacc - 800) / 5) + 65;
  
  x = ((xacc - 800) / 6) + 90;
  y = ((yacc - 700) / 6) + 100;
  
  
  
  /*
  Serial.print("output: ");
  Serial.println(x);
*/


  a = (x + y) / 2;
  b = (2*x + y) / 3;
  c = (2*y + x) / 3;
  d = (3*x + y) / 4;

  write_pot(5,x);
  write_pot(4,y);
  write_pot(3,a);
  write_pot(2,b);
  write_pot(1,c);
  write_pot(0,d);
  

}