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bmp180.c
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/* BMP180 driver fo STM32f103c8
* David Hladky
* 2015
* Version 1.0 - Update 30.9.2015
*/
#include "bmp180.h"
void bmp180_init(BMP180_calibration* calibration)
{
uint8_t buffer[22]; //Read 22 calibration bytes
uint8_t start_address = 0xAA;
HAL_I2C_Master_Transmit(&I2C1_struct,I2C_dev_add,&start_address,1,1000); // Start address of the first byte of calibration data.
HAL_I2C_Master_Receive(&I2C1_struct,I2C_dev_add,buffer,sizeof(buffer),1000); // Reading calibration data from the calibration register.
calibration->AC1 = (buffer[0]<<8)|buffer[1];
calibration->AC2 = (buffer[2]<<8)|buffer[3];
calibration->AC3 = (buffer[4]<<8)|buffer[5];
calibration->AC4 = (buffer[6]<<8)|buffer[7];
calibration->AC5 = (buffer[8]<<8)|buffer[9];
calibration->AC6 = (buffer[10]<<8)|buffer[11];
calibration->B1 = (buffer[12]<<8)|buffer[13];
calibration->B2 = (buffer[14]<<8)|buffer[15];
calibration->MB = (buffer[16]<<8)|buffer[17];
calibration->MC = (buffer[18]<<8)|buffer[19];
calibration->MD = (buffer[20]<<8)|buffer[21];
}
int32_t bmp180_get_UT(void)
{
int32_t UT;
uint8_t buffer[2], setup_buff[]={0xF4,0x2E}; // The command data to start temperature measurement.
uint8_t command = 0xF6;
HAL_I2C_Master_Transmit(&I2C1_struct,I2C_dev_add,setup_buff,sizeof(setup_buff),1000); // Start measure.
HAL_Delay(5); // Waiting for 5 ms.
HAL_I2C_Master_Transmit(&I2C1_struct,I2C_dev_add,&command,1,1000); // Read measured data from the register.
HAL_I2C_Master_Receive(&I2C1_struct,I2C_dev_add,buffer,sizeof(buffer),1000);
UT = (buffer[0]<<8)|buffer[1];
return UT;
}
int32_t bmp180_get_UP(void)
{
int32_t UP;
uint8_t buffer[3], setup_buff[]={0xF4,(0x34+(BMP180_OSS<<6))}; // The command data to start pressure measurement.
uint8_t command = 0xF6;
HAL_I2C_Master_Transmit(&I2C1_struct,I2C_dev_add,setup_buff,sizeof(setup_buff),1000); // Start measure.
HAL_Delay(25); // Waiting for 25 ms.
HAL_I2C_Master_Transmit(&I2C1_struct,I2C_dev_add,&command,1,1000); // Read measured data from the register.
HAL_I2C_Master_Receive(&I2C1_struct,I2C_dev_add,buffer,sizeof(buffer),1000);
UP = ((buffer[0]<<16)+(buffer[1]<<8)+buffer[2])>>(8-BMP180_OSS);
return UP;
}
void bmp180_get_temperature_and_preasure(BMP180_calibration* calibration, int32_t *T,int32_t *P)
{
int32_t X1, X2, X3, B3, B5, B6, UT, UP;
uint32_t B4, B7;
UT = bmp180_get_UT(); // Read uncompensated temperature value.
UP = bmp180_get_UP(); // Read uncompensated pressure value.
// Calculate the actual temperature of uncompensated values and calibration coefficients.
X1 = (((UT)-(calibration->AC6))*(calibration->AC5))/(1<<15);
X2 = ((calibration->MC)*(1<<11))/(X1+(calibration->MD));
B5 = X1+X2;
*T = (B5+8)/(1<<4); // Return actual value of the temperature.
// Calculate the actual pressure of uncompensated values and calibration coefficients.
B6 = B5-4000;
X1 = ((calibration->B2)*(B6*B6/(1<<12)))/(1<<11);
X2 = ((calibration->AC2)*B6)/(1<<11);
X3 = X1+X2;
B3 = ((((calibration->AC1)*4+X3)<<BMP180_OSS)+2)/4;
X1 = ((calibration->AC3)*B6)/(1<<13);
X2 = ((calibration->B1)*(B6*B6/(1<<12)))/(1<<16);
X3 = ((X1+X2)+2)/(1<<2);
B4 = (calibration->AC4)*(uint32_t)(X3+32768)/(1<<15);
B7 = ((uint32_t)(UP)-B3)*(50000>>BMP180_OSS);
if(B7<0x80000000)
{
*P = (B7*2)/B4;
}
else
{
*P = (B7/B4)*2;
}
X1 = ((*P)/(1<<8))*((*P)/(1<<8));
X1 = (X1*3038)/(1<<16);
X2 = (-7357*(*P))/(1<<16);
*P = (*P)+(X1+X2+3791)/(1<<4); // Return actual value of the pressure.
}