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code for MPL115 I2C MPL115A2

 
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carloshernangarrido



Joined: 02 Feb 2011
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code for MPL115 I2C MPL115A2
PostPosted: Wed Feb 02, 2011 12:53 pm     Reply with quote

Code:

/*
El presente es un programa de ejemplo con librerías para utilizar el barómetro
digital MPL115A2 con interface Soft_I2C por software.

Compiler: ccs
Author: Hernan Garrido
*/

#include <16F883.h>
#fuses HS, NOWDT, NOLVP, NOBROWNOUT, NOPROTECT, PUT
#use delay(clock=4000000)
#use rs232(baud=9600, xmit=PIN_C6, rcv=PIN_C7)

//CONSTANT DEFINITIONS
const int8 ACK = 1;  // ACKNOWLEDGE
const int8 NACK = 0;  // NOT ACKNOWLEDGE
const int8 ADDRESS_W = 0xC0;// 0x60 ADDRESS PLUS WRITE BIT
const int8 ADDRESS_R = 0xC1;// 0x60 ADDRESS PLUS READ  BIT
const int8 POUTH  = 0x00;// 10-bit pressure output value MSB 8 Yes Yes Yes
const int8 TOUTH  = 0x02;// 10-bit temperature output value MSB 8 Yes Yes Yes
const int8 BOTH   = 0x12;// Start both Conversions




//FUNCTION DECLARATIONS
void MPL115A2_init();
void MPL115A2_meas_proc();
int16 MPL115A2_read_pressure();
int16 MPL115A2_read_temperature();
int32 Presion_compensada(int16 PressCntdec, int16 TempCntdec);


void main(){
int16 P, T;


//printf("\n\rArranque");
MPL115A2_init();
//printf("\n\rInicializacion");
   
 
while (1){
   MPL115A2_meas_proc();
   //printf("\n\rMedicion");

   P = MPL115A2_read_pressure();
   //printf("\n\rLectura de presion");
   
   T = MPL115A2_read_temperature();
   //printf("\n\rLectura de temperatura");

   //printf("\n\rPresion: %Lu; Temperatura: %Lu", P, T);
   
   printf("\n\r Presion compensada %Lu Pa", Presion_compensada(P, T));
   
   delay_ms(1000);

}



}






//FUNCTION DEFINITIONS
void MPL115A2_init(){//INITIALIZES THE SOFT Soft_I2C PORT
     #use I2C(master, sda=PIN_C4, scl=PIN_C3, SLOW)
}

void MPL115A2_meas_proc(){//EXECUTE A MEASURE OF PRESSURE AND TEMPERATURE
     I2C_Start();//START BIT
     I2C_Write(ADDRESS_W);//SENDS THE ADDRESS OF THE DEVICE + WRITE
     I2C_Write(BOTH);//START BOTH CONVERSIONS
     I2C_Write(0x01);//no se porque carajo va esto, pero parece que es necesario
     I2C_Stop();
     delay_ms(10);
}

int16 MPL115A2_read_pressure(){//ask for the pressure measurement
     int16   P_MSB, P_LSB;// MS and LS bytes of pressure (8 bits variables)
     int16   P;// 10 bits pressure mesurement (16 bits variable)
     I2C_Start();//START BIT
     I2C_Write(ADDRESS_W);//IT SENDS THE ADDRESS OF THE DEVICE + WRITE
     I2C_Write(POUTH);//IT SENDS READ MSB PRESURE COMMAND
     I2C_Start();//RESTART
     I2C_Write(ADDRESS_R);//IT SENDS THE ADDRESS OF THE DEVICE + READ
     P_MSB = I2C_Read(ACK); //IT READS THE MSB AND SENDS AN ACK
     P_LSB = I2C_Read(NACK);//IT READS THE MSB AND DOES'T SEND ACK
     I2C_Stop();//IT SENDS A STOP BIT

     P = P_MSB*256 + P_LSB;
     
     //printf("\n\r P_MSB:%X; P_LSB:%X;", P_MSB, P_LSB);
     
     P=P/64;//porque los 10 bits de la medición estan amontonados del lado mas significativo
     
     DELAY_MS(10);
     return P;
}

int16 MPL115A2_read_temperature(){//ask for the pressure measurement
     int16   T_MSB, T_LSB;// MS and LS bytes of pressure (8 bits variables)
     int16   T;// 10 bits pressure mesurement (16 bits variable)
     I2C_Start();//START BIT
     I2C_Write(ADDRESS_W);//IT SENDS THE ADDRESS OF THE DEVICE + WRITE
     I2C_Write(TOUTH);//IT SENDS READ MSB TEMPERATURE COMMAND
     delay_ms(10);
     I2C_Start();//RESTART
     I2C_Write(ADDRESS_R);//IT SENDS THE ADDRESS OF THE DEVICE + READ
     delay_ms(10);
     T_MSB = I2C_Read(ACK); //IT READS THE MSB AND SENDS AN ACK
     T_LSB = I2C_Read(NACK);//IT READS THE MSB AND DOES'T SEND ACK
     I2C_Stop();//IT SENDS A STOP BIT

     T = T_MSB*256 + T_LSB;
     
     //printf("\n\r T_MSB:%X; T_LSB:%X;", T_MSB, T_LSB);
     
     
     T=T/64;//porque los 10 bits de la medición estan amontonados del lado mas significativo
     
     DELAY_MS(10);
     return T;
}



int32 Presion_compensada(unsigned int16 P, unsigned int16 T){
   // VARIABLE DEFINITIONS

   float          a0, b1, b2, c12;
   int16          w_a0, w_b1, w_b2, w_c12;//words (16bits)
   signed int16   s_w_a0, s_w_b1, s_w_b2, s_w_c12;//signed words (15bits + sign bit)

   float Pcomp;//resultado
   int32 intPcomp;
   
   float c12porTf;
   float c12porTfmasb1;
   float c12porTfmasb1porPf;
   float b2porTf;
   
   int16 I2CCoeff[12];
   
   int i=0;

   float Pf;
   float Tf;
   
   Pf = P;
   Tf = T;
   
   I2C_Start();//START BIT
   I2C_Write(ADDRESS_W);//IT SENDS THE ADDRESS OF THE DEVICE + WRITE
   I2C_Write(0x04);//IT SENDS READ MSB TEMPERATURE COMMAND
   delay_ms(10);   
   I2C_Start();//RESTART
   I2C_Write(ADDRESS_R);//IT SENDS THE ADDRESS OF THE DEVICE + READ
   delay_ms(10);
     
   for (i=0; i<12; i++){
      if (i==11){
         I2CCoeff[i] = I2C_Read(NACK); //IT READS THE MSB AND SENDS AN ACK
      }
      else{
         I2CCoeff[i] = I2C_Read(ACK); //IT READS THE MSB AND SENDS AN ACK
      }
      DELAY_MS(10);
   }

   I2C_Stop();//IT SENDS A STOP BIT

   /*printf("\n\rCoeficientes:" );
   for (i=0; i<12; i++){
      printf("%X", I2CCoeff[i]);
   }*/

   //construccion de w_a0, w_b1, w_b2, w_c12;
   w_a0 = I2CCoeff[0]*256 + I2CCoeff[1];
   w_b1 = I2CCoeff[2]*256 + I2CCoeff[3];
   w_b2 = I2CCoeff[4]*256 + I2CCoeff[5];
   w_c12= I2CCoeff[6]*256 + I2CCoeff[7];
   //c12 es de 14 bits por lo cual los dos bits menos significativos no van
   w_c12 = w_c12/4;


   //contruccion de a0
   /*1 bit de signo
   12 bits parte entera
   3bits parte fraccionaria*/
   s_w_a0 = w_a0;//para respetar el signo
   a0 = (signed int16)s_w_a0;//para pasar a flotante
   a0 = a0/8;//para ubicar la coma donde va

   //printf("\n\rCoeficiente a0:\n\r w_a0: %LX %Lu \n\r s_w_a0: %LX %Ld \n\r a0: %LX %.5f", w_a0, w_a0, s_w_a0, s_w_a0, a0, a0);
   
   
   //contruccion de b1
   /*1 bit de signo
   2 bits parte entera
   13bits parte fraccionaria*/
   s_w_b1 = w_b1;//para respetar el signo
   b1 = (signed int16)s_w_b1;//para pasar a flotante
   b1=b1/8192;//para ubicar la coma donde va

   //printf("\n\rCoeficiente b1:\n\r w_b1: %LX %Lu \n\r s_w_b1: %LX %Ld \n\r b1: %LX %.5f", w_b1, w_b1, s_w_b1, s_w_b1, b1, b1);

   //contruccion de b2
   /*1 bit de signo
   1 bits parte entera
   14bits parte fraccionaria*/
   s_w_b2 = w_b2;//para respetar el signo
   b2 = (signed int16)s_w_b2;//para pasar a flotante
   b2=b2/16384;//para ubicar la coma donde va

   //printf("\n\rCoeficiente b2:\n\r w_b2: %LX %Lu \n\r s_w_b2: %LX %Ld \n\r b2: %LX %.5f", w_b2, w_b2, s_w_b2, s_w_b2, b2, b2);
   
   
   //contruccion de c12
   /*1 bit de signo
   0 bits parte entera
   13bits parte fraccionaria
   9 ceros entre la coma y el primero de los 13 bits fraccionales
   */
   s_w_c12 = w_c12;//para respetar el signo
   c12 = (signed int16)s_w_c12;//para pasar a flotante
   c12=c12/4194304;//para ubicar la coma donde va

   //printf("\n\rCoeficiente c12:\n\r w_c12: %LX %Lu \n\r s_w_c12: %LX %Ld \n\r c12: %LX %.5f", w_c12, w_c12, s_w_c12, s_w_c12, c12, c12); 

   c12porTf = c12*Tf;
   c12porTfmasb1 = c12porTf + b1;
   c12porTfmasb1porPf = c12porTfmasb1 * Pf;
   b2porTf = b2 * Tf;
   
   Pcomp = a0 + c12porTfmasb1porPf + b2porTf;

   Pcomp = (Pcomp * 63.538611925708699902248289345064)+50000.0;

   intPcomp = Pcomp;

   return intPcomp;

}



I HOPE IT HELPS YOU!!!
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