ds1620.c

/*
  DS160 example

  Reading temperature from DS1620 digital temperature sensor 
  and showing the result via serial interface.
  
  
  Arduino    DS1620
  pin 3  ->    RST
  pin 4  ->    CLK
  pin 5  ->    DQ
  
  by Ruben Laguna
  based on examples from Tom Tigoe <http://www.arduino.cc/en/Reference/SoftwareSerialExample>
  and phanderson <http://www.phanderson.com/printer/ds1620/ds1620.html>
  written: 30 Aug 2008
  

*/

// include the SoftwareSerial library so you can use its functions:
#include <SoftwareSerial.h>

#define rxPin 0
#define txPin 1
#define ledPin 13
#define buttonPin 2

#define rstPin 3
#define clkPin 4
#define dqPin 5




// set up a new serial port
SoftwareSerial mySerial =  SoftwareSerial(rxPin, txPin);
byte pinState = 0;

void setup()  {
  // define pin modes for tx, rx, led pins:
  pinMode(rxPin, INPUT);
  pinMode(txPin, OUTPUT);
  pinMode(buttonPin, INPUT);
  pinMode(ledPin, OUTPUT);
  pinMode(rstPin, OUTPUT);
  pinMode(clkPin, OUTPUT);
  pinMode(dqPin, OUTPUT);
  
  // set the data rate for the SoftwareSerial port
  mySerial.begin(9600);
}


void loop() {
  int val = digitalRead(buttonPin);
        
    rst_low();
    
    clk_high();
    rst_high(); //all data transfer are initiated by driving RST high
    write_command(0x0c); // write config command
    write_command(0x02); // cpu mode
    rst_low();
    delay(200); //wait until the configuration register is written 
    
    clk_high();
    rst_high();
    write_command(0xEE); //start conversion
    rst_low();
    delay(200);
   
    clk_high();
    rst_high();
    write_command(0xAA);
    int raw_data = read_raw_data();
    rst_low();
    
    mySerial.print("temperature:");
    mySerial.print(raw_data/2);
    mySerial.println(" C");
    
    
    delay(100);
  
  
  // toggle an LED just so you see the thing's alive.  
  
  toggle(13);

}


void toggle(int pinNum) {
  // set the LED pin using the pinState variable:
  digitalWrite(pinNum, pinState); 
  // if pinState = 0, set it to 1, and vice versa:
  pinState = !pinState;
}

void write_command(int command)
/* sends 8 bit command on DQ output, least sig bit first */ 
{
  int n, bit;
  
  for(n=0;n<8;n++)
  {
    bit = ((command >> n) & (0x01));
    out_bit(bit);
  }
}

int read_raw_data(void)
{
  int bit,n;
  int raw_data=0;

  pinMode(dqPin,INPUT);
  
     /* jam the dq lead high to use as input */
  for(n=0;n<9;n++)
  {
     clk_low();
     bit=(digitalRead(dqPin));
     clk_high();
     raw_data = raw_data | (bit <<  n);
  }
  pinMode(dqPin, OUTPUT);
  return(raw_data);
}

void out_bit(int bit) 
{
  digitalWrite(dqPin, bit);  /* set up the data */
  clk_low();             /* and then provide a clock pulse */   
  clk_high();
}

void clk_high(void)
{
  digitalWrite(clkPin,HIGH);
}

void clk_low(void)
{
  digitalWrite(clkPin,LOW);
}

void rst_high(void)
{
   digitalWrite(rstPin,HIGH);
}

void rst_low(void)
{
   digitalWrite(rstPin,LOW);
}