BME280 library
Diff: BME280.cpp
- Revision:
- 0:b32d0acc420d
- Child:
- 1:0054d4a28927
--- /dev/null Thu Jan 01 00:00:00 1970 +0000 +++ b/BME280.cpp Mon Nov 23 07:50:28 2015 +0000 @@ -0,0 +1,213 @@ +//********************** +// 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); +} +