Pressure and temperature sensor based on BMP280
Dependents: weather_station_proj weather_station_project weather_station_proj_v1_2
Fork of BMP280 by
BMP280.cpp
- Committer:
- daniel_davvid
- Date:
- 2018-07-01
- Revision:
- 9:3a0af995dd4c
- Parent:
- 8:d22ecbef9b90
File content as of revision 9:3a0af995dd4c:
/** * BMP280 Combined humidity and pressure sensor library * * @author Toyomasa Watarai * @version 1.0 * @date 06-April-2015 * * bugfixing by charly * * Library for "BMP280 temperature, humidity and pressure sensor module" from Switch Science * https://www.switch-science.com/catalog/2236/ * * For more information about the BMP280: * http://ae-bst.resource.bosch.com/media/products/dokumente/BMP280/BST-BMP280_DS001-10.pdf */ #include "mbed.h" #include "BMP280.h" BMP280::BMP280(PinName sda, PinName scl, char slave_adr) : i2c_p(new I2C(sda, scl)), i2c(*i2c_p), address(slave_adr<<1), t_fine(0) { initialize(); } BMP280::BMP280(I2C &i2c_obj, char slave_adr) : i2c_p(NULL), i2c(i2c_obj), address(slave_adr<<1), t_fine(0) { initialize(); } BMP280::~BMP280() { if (NULL != i2c_p) delete i2c_p; } void BMP280::initialize() { char cmd[18]; //cmd[0] = 0xf2; // ctrl_hum //cmd[1] = 0x01; // Humidity oversampling x1 //i2c.write(address, cmd, 2); cmd[0] = 0xf4; // ctrl_meas //cmd[1] = 0x27; // Temparature oversampling x1, Pressure oversampling x1, Normal mode cmd[1] = 0b01010111; // Temparature oversampling x2 010, Pressure oversampling x16 101, Normal mode 11 i2c.write(address, cmd, 2); cmd[0] = 0xf5; // config cmd[1] = 0b10111100; // Standby 1000ms, Filter x16 i2c.write(address, cmd, 2); cmd[0] = 0x88; // read dig_T regs i2c.write(address, cmd, 1); i2c.read(address, cmd, 6); dig_T1 = (cmd[1] << 8) | cmd[0]; dig_T2 = (cmd[3] << 8) | cmd[2]; dig_T3 = (cmd[5] << 8) | cmd[4]; DEBUG_PRINT("dig_T = 0x%x, 0x%x, 0x%x\n\r", dig_T1, dig_T2, dig_T3); DEBUG_PRINT("dig_T = %d, %d, %d\n\r", dig_T1, dig_T2, dig_T3); cmd[0] = 0x8E; // read dig_P regs i2c.write(address, cmd, 1); i2c.read(address, cmd, 18); dig_P1 = (cmd[ 1] << 8) | cmd[ 0]; dig_P2 = (cmd[ 3] << 8) | cmd[ 2]; dig_P3 = (cmd[ 5] << 8) | cmd[ 4]; dig_P4 = (cmd[ 7] << 8) | cmd[ 6]; dig_P5 = (cmd[ 9] << 8) | cmd[ 8]; dig_P6 = (cmd[11] << 8) | cmd[10]; dig_P7 = (cmd[13] << 8) | cmd[12]; dig_P8 = (cmd[15] << 8) | cmd[14]; dig_P9 = (cmd[17] << 8) | cmd[16]; DEBUG_PRINT("dig_P = 0x%x, 0x%x, 0x%x, 0x%x, 0x%x, 0x%x, 0x%x, 0x%x, 0x%x\n", dig_P1, dig_P2, dig_P3, dig_P4, dig_P5, dig_P6, dig_P7, dig_P8, dig_P9); /* cmd[0] = 0xA1; // read dig_H regs i2c.write(address, cmd, 1); i2c.read(address, cmd, 1); cmd[1] = 0xE1; // read dig_H regs i2c.write(address, &cmd[1], 1); i2c.read(address, &cmd[1], 7); dig_H1 = cmd[0]; dig_H2 = (cmd[2] << 8) | cmd[1]; dig_H3 = cmd[3]; dig_H4 = (cmd[4] << 4) | (cmd[5] & 0x0f); dig_H5 = (cmd[6] << 4) | ((cmd[5]>>4) & 0x0f); dig_H6 = cmd[7]; DEBUG_PRINT("dig_H = 0x%x, 0x%x, 0x%x, 0x%x, 0x%x, 0x%x\n", dig_H1, dig_H2, dig_H3, dig_H4, dig_H5, dig_H6); */ } float BMP280::getTemperature() { int32_t temp_raw; float tempf; char cmd[4]; cmd[0] = 0xfa; // temp_msb i2c.write(address, cmd, 1); i2c.read(address, &cmd[1], 3); temp_raw = (cmd[1] << 12) | (cmd[2] << 4) | (cmd[3] >> 4); DEBUG_PRINT("\r\ntemp_raw:%d",temp_raw); int32_t temp1, temp2,temp; temp1 =((((temp_raw >> 3) - (dig_T1 << 1))) * dig_T2) >> 11; temp2 =(((((temp_raw >> 4) - dig_T1) * ((temp_raw >> 4) - dig_T1)) >> 12) * dig_T3) >> 14; DEBUG_PRINT(" temp1:%d temp2:%d",temp1, temp2); t_fine = temp1+temp2; DEBUG_PRINT(" t_fine:%d",t_fine); temp = (t_fine * 5 + 128) >> 8; tempf = (float)temp; DEBUG_PRINT(" tempf:%f",tempf); return (tempf/100.0f); } float BMP280::getPressure() { uint32_t press_raw; float pressf; char cmd[4]; cmd[0] = 0xf7; // press_msb i2c.write(address, cmd, 1); i2c.read(address, &cmd[1], 3); press_raw = (cmd[1] << 12) | (cmd[2] << 4) | (cmd[3] >> 4); int32_t var1, var2; uint32_t press; 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) { return 0; } press = (((1048576 - press_raw) - (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)); pressf = (float)press; return (pressf/100.0f); }