Thermal Flashlight (RGB LED + Melexis 90614 + Arduino)

i2cmaster.h

#ifndef _I2CMASTER_H
#define _I2CMASTER_H   1
/************************************************************************* 
* Title:    C include file for the I2C master interface 
*           (i2cmaster.S or twimaster.c)
* Author:   Peter Fleury <pfleury@gmx.ch>  http://jump.to/fleury
* File:     $Id: i2cmaster.h,v 1.10 2005/03/06 22:39:57 Peter Exp $
* Software: AVR-GCC 3.4.3 / avr-libc 1.2.3
* Target:   any AVR device
* Usage:    see Doxygen manual
**************************************************************************/

#ifdef DOXYGEN
/**
 @defgroup pfleury_ic2master I2C Master library
 @code #include <i2cmaster.h> @endcode
  
 @brief I2C (TWI) Master Software Library

 Basic routines for communicating with I2C slave devices. This single master 
 implementation is limited to one bus master on the I2C bus. 

 This I2c library is implemented as a compact assembler software implementation of the I2C protocol 
 which runs on any AVR (i2cmaster.S) and as a TWI hardware interface for all AVR with built-in TWI hardware (twimaster.c).
 Since the API for these two implementations is exactly the same, an application can be linked either against the
 software I2C implementation or the hardware I2C implementation.

 Use 4.7k pull-up resistor on the SDA and SCL pin.
 
 Adapt the SCL and SDA port and pin definitions and eventually the delay routine in the module 
 i2cmaster.S to your target when using the software I2C implementation ! 
 
 Adjust the  CPU clock frequence F_CPU in twimaster.c or in the Makfile when using the TWI hardware implementaion.

 @note 
    The module i2cmaster.S is based on the Atmel Application Note AVR300, corrected and adapted 
    to GNU assembler and AVR-GCC C call interface.
    Replaced the incorrect quarter period delays found in AVR300 with 
    half period delays. 
    
 @author Peter Fleury pfleury@gmx.ch  http://jump.to/fleury

 @par API Usage Example
  The following code shows typical usage of this library, see example test_i2cmaster.c

 @code

 #include <i2cmaster.h>


 #define Dev24C02  0xA2      // device address of EEPROM 24C02, see datasheet

 int main(void)
 {
     unsigned char ret;

     i2c_init();                             // initialize I2C library

     // write 0x75 to EEPROM address 5 (Byte Write) 
     i2c_start_wait(Dev24C02+I2C_WRITE);     // set device address and write mode
     i2c_write(0x05);                        // write address = 5
     i2c_write(0x75);                        // write value 0x75 to EEPROM
     i2c_stop();                             // set stop conditon = release bus


     // read previously written value back from EEPROM address 5 
     i2c_start_wait(Dev24C02+I2C_WRITE);     // set device address and write mode

     i2c_write(0x05);                        // write address = 5
     i2c_rep_start(Dev24C02+I2C_READ);       // set device address and read mode

     ret = i2c_readNak();                    // read one byte from EEPROM
     i2c_stop();

     for(;;);
 }
 @endcode

*/
#endif /* DOXYGEN */

/**@{*/

#if (__GNUC__ * 100 + __GNUC_MINOR__) < 304
#error "This library requires AVR-GCC 3.4 or later, update to newer AVR-GCC compiler !"
#endif

#include <avr/io.h>

/** defines the data direction (reading from I2C device) in i2c_start(),i2c_rep_start() */
#define I2C_READ    1

/** defines the data direction (writing to I2C device) in i2c_start(),i2c_rep_start() */
#define I2C_WRITE   0


/**
 @brief initialize the I2C master interace. Need to be called only once 
 @param  void
 @return none
 */
extern void i2c_init(void);


/** 
 @brief Terminates the data transfer and releases the I2C bus 
 @param void
 @return none
 */
extern void i2c_stop(void);


/** 
 @brief Issues a start condition and sends address and transfer direction 
  
 @param    addr address and transfer direction of I2C device
 @retval   0   device accessible 
 @retval   1   failed to access device 
 */
extern unsigned char i2c_start(unsigned char addr);


/**
 @brief Issues a repeated start condition and sends address and transfer direction 

 @param   addr address and transfer direction of I2C device
 @retval  0 device accessible
 @retval  1 failed to access device
 */
extern unsigned char i2c_rep_start(unsigned char addr);


/**
 @brief Issues a start condition and sends address and transfer direction 
   
 If device is busy, use ack polling to wait until device ready 
 @param    addr address and transfer direction of I2C device
 @return   none
 */
extern void i2c_start_wait(unsigned char addr);

 
/**
 @brief Send one byte to I2C device
 @param    data  byte to be transfered
 @retval   0 write successful
 @retval   1 write failed
 */
extern unsigned char i2c_write(unsigned char data);


/**
 @brief    read one byte from the I2C device, request more data from device 
 @return   byte read from I2C device
 */
extern unsigned char i2c_readAck(void);

/**
 @brief    read one byte from the I2C device, read is followed by a stop condition 
 @return   byte read from I2C device
 */
extern unsigned char i2c_readNak(void);

/** 
 @brief    read one byte from the I2C device
 
 Implemented as a macro, which calls either i2c_readAck or i2c_readNak
 
 @param    ack 1 send ack, request more data from device<br>
               0 send nak, read is followed by a stop condition 
 @return   byte read from I2C device
 */
extern unsigned char i2c_read(unsigned char ack);
#define i2c_read(ack)  (ack) ? i2c_readAck() : i2c_readNak(); 


/**@}*/
#endif

ThermalFlashlight.ino

// See http://bildr.org/2011/02/mlx90614-arduino/ for i2c library and instructions
// You must download the "twimaster.cpp" and "i2cmaster.h" files, and place them in a folder called "I2Cmaster". This must be placed in a folder called "libraries" which in turn should be placed in your Sketchbook folder (see Arduino's Preferences menu item to see where this is on your machine.).
// Typically, once you install these files, you must relaunch Arduino.

// The extra files are included in this Gist, as well as attached to the page http://publiclaboratory.org/tool/thermal-camera

#include <i2cmaster.h>
#include "Wire.h"
//#include "BlinkM_funcs.h"

const float lowReading = 60;
const float highReading = 75;
const unsigned char separatorCharacter = 255;

void setup(){
  
  pinMode(9,OUTPUT);
  pinMode(10,OUTPUT);
  pinMode(11,OUTPUT);
  Serial.begin(9600);
  Serial.println("starting setup...");  

  i2c_init(); //Initialise the i2c bus
  PORTC = (1 << PORTC4) | (1 << PORTC5);//enable pullups
  Serial.println("completed setup");
}

float normf(float x, float low, float high) {
  float y = (x - low) * 255.f / (high - low);
  if(y > 255) {
    y = 255;
  }
  if(y < 0) {
    y = 0;
  }
  return y;
}

void loop(){
  int dev = 0x5A<<1;
  int data_low = 0;
  int data_high = 0;
  int pec = 0;

  i2c_start_wait(dev+I2C_WRITE);
  i2c_write(0x07);

  // read
  i2c_rep_start(dev+I2C_READ);
  data_low = i2c_readAck(); //Read 1 byte and then send ack
  data_high = i2c_readAck(); //Read 1 byte and then send ack
  pec = i2c_readNak();
  i2c_stop();

  //This converts high and low bytes together and processes temperature, MSB is a error bit and is ignored for temps
  double tempFactor = 0.02; // 0.02 degrees per LSB (measurement resolution of the MLX90614)
  double tempData = 0x0000; // zero out the data
  int frac; // data past the decimal point

  // This masks off the error bit of the high byte, then moves it left 8 bits and adds the low byte.
  tempData = (double)(((data_high & 0x007F) << 8) + data_low);
  tempData = (tempData * tempFactor)-0.01;
  float celcius = tempData - 273.15;  
  float fahrenheit = (celcius*1.8) + 32;
  
  //Serial.println(fahrenheit);
  
  float state = normf(fahrenheit, lowReading, highReading);
  //Serial.write((unsigned int) state);
  //Serial.write(separatorCharacter);
  
  // BlinkM MaxM super-bright LED:
  // 165 is blue, 0 is red
  //BlinkM_fadeToHSB(blinkm_addr, map(state, 0, 255, 165, 0), 255, 255);

  // Regular ol' RGB LED:
  int hue = map(state,0,255,359,(359*0.5)); // not the whole color wheel
  setLedColorHSV(hue,1,1); //We are using Saturation and Value constant at 1

  Serial.print(fahrenheit);
  Serial.print(" degrees F, hue: ");
  Serial.println(+hue);

}
//Convert a given HSV (Hue Saturation Value) to RGB(Red Green Blue) and set the led to the color
//  h is hue value, integer between 0 and 360
//  s is saturation value, double between 0 and 1
//  v is value, double between 0 and 1
//http://splinter.com.au/blog/?p=29
void setLedColorHSV(int h, double s, double v) {
  //this is the algorithm to convert from RGB to HSV
  double r=0; 
  double g=0; 
  double b=0;

  double hf=h/60.0;

  int i=(int)floor(h/60.0);
  double f = h/60.0 - i;
  double pv = v * (1 - s);
  double qv = v * (1 - s*f);
  double tv = v * (1 - s * (1 - f));

  switch (i)
  {
  case 0: //rojo dominante
    r = v;
    g = tv;
    b = pv;
    break;
  case 1: //verde
    r = qv;
    g = v;
    b = pv;
    break;
  case 2: 
    r = pv;
    g = v;
    b = tv;
    break;
  case 3: //azul
    r = pv;
    g = qv;
    b = v;
    break;
  case 4:
    r = tv;
    g = pv;
    b = v;
    break;
  case 5: //rojo
    r = v;
    g = pv;
    b = qv;
    break;
  }

  //set each component to a integer value between 0 and 255
  int red=constrain((int)255*r,0,255);
  int green=constrain((int)255*g,0,255);
  int blue=constrain((int)255*b,0,255);

  setLedColor(red,green,blue);
}

//Sets the current color for the RGB LED
void setLedColor(int red, int green, int blue) {
  //Note that we are reducing 1/4 the intensity for the green and blue components because 
  //  the red one is too dim on my LED. You may want to adjust that.
  analogWrite(9,red); //Red pin attached to 9
  analogWrite(10,green); //Red pin attached to 9
  analogWrite(11,blue); //Red pin attached to 9
}

twimaster.cpp

/*************************************************************************
* Title:    I2C master library using hardware TWI interface
* Author:   Peter Fleury <pfleury@gmx.ch>  http://jump.to/fleury
* File:     $Id: twimaster.c,v 1.3 2005/07/02 11:14:21 Peter Exp $
* Software: AVR-GCC 3.4.3 / avr-libc 1.2.3
* Target:   any AVR device with hardware TWI 
* Usage:    API compatible with I2C Software Library i2cmaster.h
**************************************************************************/
#include <inttypes.h>
#include <compat/twi.h>

#include <i2cmaster.h>


/* define CPU frequency in Mhz here if not defined in Makefile */
#ifndef F_CPU
#define F_CPU 16000000UL
#endif
 
/* I2C clock in Hz */
#define SCL_CLOCK 50000L


/*************************************************************************
 Initialization of the I2C bus interface. Need to be called only once
*************************************************************************/
void i2c_init(void)
{
  /* initialize TWI clock: 100 kHz clock, TWPS = 0 => prescaler = 1 */
  
  TWSR = 0;                         /* no prescaler */
  TWBR = ((F_CPU/SCL_CLOCK)-16)/2;  /* must be > 10 for stable operation */

}/* i2c_init */


/*************************************************************************	
  Issues a start condition and sends address and transfer direction.
  return 0 = device accessible, 1= failed to access device
*************************************************************************/
unsigned char i2c_start(unsigned char address)
{
    uint8_t   twst;

	// send START condition
	TWCR = (1<<TWINT) | (1<<TWSTA) | (1<<TWEN);

	// wait until transmission completed
	while(!(TWCR & (1<<TWINT)));

	// check value of TWI Status Register. Mask prescaler bits.
	twst = TW_STATUS & 0xF8;
	if ( (twst != TW_START) && (twst != TW_REP_START)) return 1;

	// send device address
	TWDR = address;
	TWCR = (1<<TWINT) | (1<<TWEN);

	// wail until transmission completed and ACK/NACK has been received
	while(!(TWCR & (1<<TWINT)));

	// check value of TWI Status Register. Mask prescaler bits.
	twst = TW_STATUS & 0xF8;
	if ( (twst != TW_MT_SLA_ACK) && (twst != TW_MR_SLA_ACK) ) return 1;

	return 0;

}/* i2c_start */


/*************************************************************************
 Issues a start condition and sends address and transfer direction.
 If device is busy, use ack polling to wait until device is ready
 
 Input:   address and transfer direction of I2C device
*************************************************************************/
void i2c_start_wait(unsigned char address)
{
    uint8_t   twst;


    while ( 1 )
    {
	    // send START condition
	    TWCR = (1<<TWINT) | (1<<TWSTA) | (1<<TWEN);
    
    	// wait until transmission completed
    	while(!(TWCR & (1<<TWINT)));
    
    	// check value of TWI Status Register. Mask prescaler bits.
    	twst = TW_STATUS & 0xF8;
    	if ( (twst != TW_START) && (twst != TW_REP_START)) continue;
    
    	// send device address
    	TWDR = address;
    	TWCR = (1<<TWINT) | (1<<TWEN);
    
    	// wail until transmission completed
    	while(!(TWCR & (1<<TWINT)));
    
    	// check value of TWI Status Register. Mask prescaler bits.
    	twst = TW_STATUS & 0xF8;
    	if ( (twst == TW_MT_SLA_NACK )||(twst ==TW_MR_DATA_NACK) ) 
    	{    	    
    	    /* device busy, send stop condition to terminate write operation */
	        TWCR = (1<<TWINT) | (1<<TWEN) | (1<<TWSTO);
	        
	        // wait until stop condition is executed and bus released
	        while(TWCR & (1<<TWSTO));
	        
    	    continue;
    	}
    	//if( twst != TW_MT_SLA_ACK) return 1;
    	break;
     }

}/* i2c_start_wait */


/*************************************************************************
 Issues a repeated start condition and sends address and transfer direction 

 Input:   address and transfer direction of I2C device
 
 Return:  0 device accessible
          1 failed to access device
*************************************************************************/
unsigned char i2c_rep_start(unsigned char address)
{
    return i2c_start( address );

}/* i2c_rep_start */


/*************************************************************************
 Terminates the data transfer and releases the I2C bus
*************************************************************************/
void i2c_stop(void)
{
    /* send stop condition */
	TWCR = (1<<TWINT) | (1<<TWEN) | (1<<TWSTO);
	
	// wait until stop condition is executed and bus released
	while(TWCR & (1<<TWSTO));

}/* i2c_stop */


/*************************************************************************
  Send one byte to I2C device
  
  Input:    byte to be transfered
  Return:   0 write successful 
            1 write failed
*************************************************************************/
unsigned char i2c_write( unsigned char data )
{	
    uint8_t   twst;
    
	// send data to the previously addressed device
	TWDR = data;
	TWCR = (1<<TWINT) | (1<<TWEN);

	// wait until transmission completed
	while(!(TWCR & (1<<TWINT)));

	// check value of TWI Status Register. Mask prescaler bits
	twst = TW_STATUS & 0xF8;
	if( twst != TW_MT_DATA_ACK) return 1;
	return 0;

}/* i2c_write */


/*************************************************************************
 Read one byte from the I2C device, request more data from device 
 
 Return:  byte read from I2C device
*************************************************************************/
unsigned char i2c_readAck(void)
{
	TWCR = (1<<TWINT) | (1<<TWEN) | (1<<TWEA);
	while(!(TWCR & (1<<TWINT)));    

    return TWDR;

}/* i2c_readAck */


/*************************************************************************
 Read one byte from the I2C device, read is followed by a stop condition 
 
 Return:  byte read from I2C device
*************************************************************************/
unsigned char i2c_readNak(void)
{
	TWCR = (1<<TWINT) | (1<<TWEN);
	while(!(TWCR & (1<<TWINT)));
	
    return TWDR;

}/* i2c_readNak */