BMP280 temperature & pressure
BMP280.cpp
- Committer:
- johnathanlyu
- Date:
- 2018-04-27
- Revision:
- 1:9bb59e83df7a
- Parent:
- 0:c2987bafde6c
File content as of revision 1:9bb59e83df7a:
#include "BMP280.h" void BMP280::write(char reg, char ctrl) { char data[2] = {reg, ctrl}; m_i2c.write(BMP280_ADDR, data, 2, false); } void BMP280::read(char reg, char *data, int length) { m_i2c.write(BMP280_ADDR, ®, 1, false); m_i2c.read(BMP280_ADDR+1, data, length, false); } BMP280::BMP280(I2C& i2c) : m_i2c(i2c), pc(p5,p4) { char begin = BMP280_REG_CALIBRATION; char bf[24]; read(begin, bf, 24); dig_T1 = (bf[1]<<8) | bf[0]; dig_T2 = (bf[3]<<8) | bf[2]; dig_T3 = (bf[5]<<8) | bf[4]; dig_P1 = (bf[7]<<8) | bf[6]; dig_P2 = (bf[9]<<8) | bf[8]; dig_P3 = (bf[11]<<8) | bf[10]; dig_P4 = (bf[13]<<8) | bf[12]; dig_P5 = (bf[15]<<8) | bf[14]; dig_P6 = (bf[17]<<8) | bf[16]; dig_P7 = (bf[19]<<8) | bf[18]; dig_P8 = (bf[21]<<8) | bf[20]; dig_P9 = (bf[23]<<8) | bf[22]; } int BMP280::init(char ctrl_meas , char config) { char reg_ctrl, reg_config; reg_ctrl = BMP280_REG_CTRL_MEAS; reg_config = BMP280_REG_CONFIG; write(reg_ctrl, ctrl_meas); write(reg_config, config); // pc.printf("t1:%d, t2:%d, t3:%d\r\n", dig_T1, dig_T2, dig_T3); // pc.printf("p1:%d, p2:%d, p3:%d, p4:%d, p5:%d, p6:%d, p7:%d, p8:%d, p9:%d\r\n", dig_P1, dig_P2, dig_P3, dig_P4, dig_P5, dig_P6, dig_P7, dig_P8, dig_P9); return 0; } int BMP280::readData(float *tempC, int *pressPa) { int var1,var2,T; int t_fine; unsigned int press=0; char read_reg = BMP280_REG_PRESS; char rx[6]; int adc_T,adc_P; read(read_reg, rx, 6); adc_T = ((rx[3]<<12)|(rx[4]<<4)|rx[5]>>4); adc_P = ((rx[0]<<12)|(rx[1]<<4)|rx[2]>>4); // pc.printf("adc_T %d, adc_p %d\r\n", adc_T, adc_P); var1=((((adc_T>>3)-((int)dig_T1<<1)))*((int)dig_T2))>>11; var2=(((((adc_T>>4)-((int)dig_T1))*((adc_T>>4)-((int)dig_T1)))>>12)*((int)dig_T3))>>14; t_fine=var1+var2; T=(t_fine*5+128)>>8; *tempC = T/100.0; // pc.printf("BMP280 T %d\r\n", T); var1 = (t_fine >> 1) - 64000; var2 = (((var1 >> 2) * (var1 >> 2)) >> 11) * dig_P6; var2 = var2 + ((var1 * dig_P5) << 1); var2 = (var2 >> 2) + (dig_P4 << 16); var1 = (((dig_P3 * (((var1 >> 2)*(var1 >> 2)) >> 13)) >> 3) + ((dig_P2 * var1) >> 1)) >> 18; var1 = ((32768 + var1) * dig_P1) >> 15; if (var1 == 0) { // pc.printf("var1 is zero!\r\n"); } press = (((1048576 - adc_P) - (var2 >> 12))) * 3125; if(press < 0x80000000) { press = (press << 1) / var1; } else { press = (press / var1) * 2; } var1 = ((int32_t)dig_P9 * ((int32_t)(((press >> 3) * (press >> 3)) >> 13))) >> 12; var2 = (((int32_t)(press >> 2)) * (int32_t)dig_P8) >> 13; press = (press + ((var1 + var2 + dig_P7) >> 4)); *pressPa = press; // pc.printf("press is %d\r\n", press); return 0; }