carloshernangarrido
Joined: 02 Feb 2011
Posts: 1
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| code for MPL115 I2C MPL115A2 |
 Posted: Wed Feb 02, 2011 12:53 pm |
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| 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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