BME280 library
BME280.cpp
- Committer:
- yasuyuki
- Date:
- 2015-11-23
- Revision:
- 0:b32d0acc420d
- Child:
- 1:0054d4a28927
File content as of revision 0:b32d0acc420d:
//********************** // BME280.cpp for mbed // // BME280 bme280(P0_5,P0_4); // or // I2C i2c(P0_5,P0_4); // BME280 bme280(i2c); // // (C)Copyright 2015 All rights reserved by Y.Onodera // http://einstlab.web.fc2.com //********************** #include "mbed.h" #include "BME280.h" BME280::BME280 (PinName sda, PinName scl) : _i2c(sda, scl) { init(); } BME280::BME280 (I2C& p_i2c) : _i2c(p_i2c) { init(); } unsigned char BME280::get(unsigned char a) { buf[0] = a; // register _i2c.write(BME280_ADDR, buf, 1); // with stop // get data _i2c.read( BME280_ADDR, buf, 1); return buf[0]; } void BME280::set(unsigned char a, unsigned char b) { buf[0] = a; // register buf[1] = b; _i2c.write(BME280_ADDR, buf, 2); // with stop } void BME280::getALL() { // set ctrl_meas : forced mode set(ctrl_meas, 0x25); // wait status if(get(status) != 0)wait_ms(1); // get temp temp.XLSB = get(temp_xlsb); temp.LSB = get(temp_lsb); temp.MSB = get(temp_msb); temp.dummy = 0; // get press press.XLSB = get(press_xlsb); press.LSB = get(press_lsb); press.MSB = get(press_msb); press.dummy = 0; // get hum hum.LSB = get(hum_lsb); hum.MSB = get(hum_msb); // compensation t = BME280_compensate_T_int32(temp.s32>>12); p = BME280_compensate_P_int64(press.s32>>12); h = BME280_compensate_H_int32((signed int)hum.u16); } unsigned int BME280::humidity() { // get hum getALL(); return h; } signed int BME280::temperature() { // get temp getALL(); return t; } unsigned int BME280::pressure() { // get hum getALL(); return p; } void BME280::init() { // get calibrations calib.LSB = get(calib00); calib.MSB = get(calib01); dig_T1 = calib.u16; calib.LSB = get(calib02); calib.MSB = get(calib03); dig_T2 = calib.s16; calib.LSB = get(calib04); calib.MSB = get(calib05); dig_T3 = calib.s16; calib.LSB = get(calib06); calib.MSB = get(calib07); dig_P1 = calib.u16; calib.LSB = get(calib08); calib.MSB = get(calib09); dig_P2 = calib.s16; calib.LSB = get(calib10); calib.MSB = get(calib11); dig_P3 = calib.s16; calib.LSB = get(calib12); calib.MSB = get(calib13); dig_P4 = calib.s16; calib.LSB = get(calib14); calib.MSB = get(calib15); dig_P5 = calib.s16; calib.LSB = get(calib16); calib.MSB = get(calib17); dig_P6 = calib.s16; calib.LSB = get(calib18); calib.MSB = get(calib19); dig_P7 = calib.s16; calib.LSB = get(calib20); calib.MSB = get(calib21); dig_P8 = calib.s16; calib.LSB = get(calib22); calib.MSB = get(calib23); dig_P9 = calib.s16; dig_H1 = get(calib25); calib.LSB = get(calib26); calib.MSB = get(calib27); dig_H2 = calib.s16; dig_H3 = get(calib28); calib.MSB = get(calib29); calib.LSB = get(calib30) << 4; dig_H4 = calib.s16>>4; calib.LSB = get(calib30); calib.MSB = get(calib31); dig_H5 = calib.s16>>4; dig_H6 = get(calib32); // Set configuration set(config, 0x00); set(ctrl_hum, 0x01); } // Returns temperature in DegC, resolution is 0.01 DegC. Output value of "5123" equals 51.23 DegC. // t_fine carries fine temperature as global value BME280_S32_t BME280::BME280_compensate_T_int32(BME280_S32_t adc_T) { BME280_S32_t var1, var2, T; var1 = ((((adc_T>>3) - ((BME280_S32_t)dig_T1<<1))) * ((BME280_S32_t)dig_T2)) >> 11; var2 = (((((adc_T>>4) - ((BME280_S32_t)dig_T1)) * ((adc_T>>4) - ((BME280_S32_t)dig_T1))) >> 12) * ((BME280_S32_t)dig_T3)) >> 14; t_fine = var1 + var2; T = (t_fine * 5 + 128) >> 8; return T; } // Returns pressure in Pa as unsigned 32 bit integer in Q24.8 format (24 integer bits and 8 fractional bits). // Output value of "24674867" represents 24674867/256 = 96386.2 Pa = 963.862 hPa BME280_U32_t BME280::BME280_compensate_P_int64(BME280_S32_t adc_P) { BME280_S64_t var1, var2, p; var1 = ((BME280_S64_t)t_fine) - 128000; var2 = var1 * var1 * (BME280_S64_t)dig_P6; var2 = var2 + ((var1*(BME280_S64_t)dig_P5)<<17); var2 = var2 + (((BME280_S64_t)dig_P4)<<35); var1 = ((var1 * var1 * (BME280_S64_t)dig_P3)>>8) + ((var1 * (BME280_S64_t)dig_P2)<<12); var1 = (((((BME280_S64_t)1)<<47)+var1))*((BME280_S64_t)dig_P1)>>33; if (var1 == 0) { return 0; // avoid exception caused by division by zero } p = 1048576-adc_P; p = (((p<<31)-var2)*3125)/var1; var1 = (((BME280_S64_t)dig_P9) * (p>>13) * (p>>13)) >> 25; var2 = (((BME280_S64_t)dig_P8) * p) >> 19; p = ((p + var1 + var2) >> 8) + (((BME280_S64_t)dig_P7)<<4); return (BME280_U32_t)p; } // Returns humidity in %RH as unsigned 32 bit integer in Q22.10 format (22 integer and 10 fractional bits). // Output value of "47445" represents 47445/1024 = 46.333 %RH BME280_U32_t BME280::BME280_compensate_H_int32(BME280_S32_t adc_H) { BME280_S32_t v_x1_u32r; v_x1_u32r = (t_fine - ((BME280_S32_t)76800)); v_x1_u32r = (((((adc_H << 14) - (((BME280_S32_t)dig_H4) << 20) - (((BME280_S32_t)dig_H5) * v_x1_u32r)) + ((BME280_S32_t)16384)) >> 15) * (((((((v_x1_u32r * ((BME280_S32_t)dig_H6)) >> 10) * (((v_x1_u32r * ((BME280_S32_t)dig_H3)) >> 11) + ((BME280_S32_t)32768))) >> 10) + ((BME280_S32_t)2097152)) * ((BME280_S32_t)dig_H2) + 8192) >> 14)); v_x1_u32r = (v_x1_u32r - (((((v_x1_u32r >> 15) * (v_x1_u32r >> 15)) >> 7) * ((BME280_S32_t)dig_H1)) >> 4)); v_x1_u32r = (v_x1_u32r < 0 ? 0 : v_x1_u32r); v_x1_u32r = (v_x1_u32r > 419430400 ? 419430400 : v_x1_u32r); return (BME280_U32_t)(v_x1_u32r>>12); }