t_measure.c

schduler for AVR mcu

/*
------------------------------------------------------------------*-

   T_Measure.C (v1.00)

  ------------------------------------------------------------------
   
   LCD display  program (Test Version 1.0)


   COPYRIGHT
   ---------

   This code is from the book:

   PATTERNS FOR TIME-TRIGGERED EMBEDDED SYSTEMS by Michael J. Pont 
   [Pearson Education, 2001; ISBN: 0-201-33138-1].

   This code is copyright (c) 2001 by Michael J. Pont.
 
   --- Modefied by  sylva zhu to apply for  AVR Microcontroller .
   --- Ver 1.0  Sept 25th , 2006 .

-*------------------------------------------------------------------
*/

#include  <iom32.h>
#include  <inavr.h>
#include  <comp_a90.h>
#include  <math.h>

#include  "T_Measure.h"
#include  "T_Lcd.h"
//
//
//  Global variables
 unsigned char ADCresult_calc_cnt = 0;   // variable to count number of temperature calcualtions
 unsigned int ADCresult_average = 0;              // integer to keep the ADC results for later averaging
 float Temperature;                      // float to calculate the temperature
 unsigned int  TEMP_HIGHBYTE;
 unsigned int  TEMP_LOWBYTE;
 //
 unsigned char temp_hundred;
 unsigned char temp_ten;
 unsigned char temp_zero;
 unsigned char temp_subone;
 unsigned char temp_subtwo;

//
//
static void ADC_conv_temp(void);
static void Temp_calculation(unsigned int iADC_value);
//
//------------------------------------------------------------------------------
//
void ADC_Update(void)
{
   ADC_conv_temp();
}
/*
********************************************************************************
*
*	Function name :    ADC_conversion
*
*	Returns :	   None
*
*	Parameters :	   None
*
*	Purpose :	  Run the ADC conversion 
*
********************************************************************************
*/
static void ADC_conv_temp(void)
{
    unsigned int ADC_temp;
    unsigned int ADCresult = 0;
    unsigned char i;
    
    for(i=0;i<8;i++)                // do the ADC conversion 8 times for better accuracy 
      {
        ADCSRA |= (1<<ADSC);        // do single conversion
        while(!(ADCSRA & 0x10));    // wait for conversion done, ADIF flag active

        ADC_temp = (unsigned int)ADCL;       // read out ADCL register
        ADC_temp += ((unsigned int)ADCH*256);    // read out ADCH register        

        ADCresult += ADC_temp;      // accumulate result (8 samples) for later averaging
      }
    
    //ADCresult = ADCresult >> 3;     // average the 8 samples
    ADCresult=ADCresult/8;

    ADCresult_calc_cnt++;           // increment the counter that keeps track of how many calulations that have been donet 
    
    ADCresult_average += ADCresult; // add the ADCresult to the previous measurements
    
    if(ADCresult_calc_cnt >= 32)    // if 32 calculations
      {
        ADCresult_calc_cnt = 0;     // clear the counter
       
        //ADCresult_average = ADCresult_average >> 5;   // find the average ADC result for the last 32 times
        ADCresult_average=ADCresult_average/32;
        
        Temp_calculation(ADCresult_average);       // call the temperature calculation function

        ADCresult_average = 0;      // clear the ADCresult_average
      }   
}

/*
********************************************************************************
*
*	Function name : Temp_calculation
*
*	Returns :		None
*
*	Parameters :	The result in the ADCH/L registers
*
*	Purpose :		Calculate the corresponding temperature in degree Celsius, 
*                   and place the value in SRAM at location 0x4F0 - 0x4FF
*
********************************************************************************
*/

static void Temp_calculation(unsigned int iADC_value)//ADCresult_average
{
     float V_ADC;
    
    //if((ADMUX & 0x1F) == SingleEnded)               // check if Single_ended operation
        V_ADC = (iADC_value * V_ref)/1024;          // calculate the voltage over the NTC
    //else if((ADMUX & 0x1F) == Differential)         // check if Differential operation
        //V_ADC = (iADC_value * V_ref)/512;           // calculate the voltage over the NTC
    // float temperature
    Temperature = Beta/( log(V_ADC/(V_ref-V_ADC))/log(__E) + (Beta/T_amb) ) -T_zero-470;   // calculate the temperature
    // int TEMP_HIGHBYTE , FLOAT Temperature 
    TEMP_HIGHBYTE = Temperature;                    // store the integer to "TEMP_HIGHBYTE"
    Temperature = (Temperature - TEMP_HIGHBYTE);    // subtract the the integer from Temperature_average ,
                                                     //ang get value below littel digital value.       
    TEMP_LOWBYTE = (Temperature * 100);             // multiply Temperature_average by 100 to get the decimal,
                                                    // and store it to "TEMP_LOWBYTE"
                                                    //************************************** int . int
                                                    //                             TEMP_HITHBYTE . TEMP_LOWBYTE
    //Temperature_regulation();                       //call the Temperatur_regulation rutine
    
    temp_hundred=(unsigned char)(TEMP_HIGHBYTE%1000/100);
    temp_ten=(unsigned char)(TEMP_HIGHBYTE%100/10);
    temp_zero=(unsigned char)(TEMP_HIGHBYTE%10);
    temp_subone=(unsigned char)(TEMP_LOWBYTE%1000/100);
    temp_subtwo=(unsigned char)(TEMP_LOWBYTE%100/10);
    //
    if(temp_hundred==0)
       {
         ShowChar(0x2d,' ');
        }
    else
       {
         ShowChar(0x2d,temp_hundred+0x30);
        }
    ShowChar(0x2e,temp_ten+0x30);
    ShowChar(0x2f,temp_zero+0x30);
    ShowChar(0x30,'.');
    ShowChar(0x31,temp_subone+0x30);
    ShowChar(0x32,temp_subtwo+0x30);
    ShowChar(0x33,' ');
    ShowChar(0x34,'D');
    ShowChar(0x35,'E');
    ShowChar(0x36,'G');
    ShowChar(0x37,'R');
    ShowChar(0x38,'E');
    ShowChar(0x39,'E');
    ShowChar(0x3a,' ');
    ShowChar(0x3b,' ');
    
}