Implemented first Hangar-Service
Dependencies: CalibrateMagneto QuaternionMath
Fork of SML2 by
Barometer.cpp
- Committer:
- pvaibhav
- Date:
- 2015-01-23
- Revision:
- 4:e759b8c756da
- Parent:
- 3:ee90a9ada112
- Child:
- 16:3e2468d4f4c1
File content as of revision 4:e759b8c756da:
#include "Barometer.h" #define DEBUG "BMP280" #include "Logger.h" Barometer::Barometer(I2C &i2c) : I2CPeripheral(i2c, 0xEC /* address */) { write_reg(0xE0, 0xB6); // reset wait_ms(2); // cf. datasheet page 8, t_startup const uint8_t chip_id = read_reg(0xD0); if (chip_id == 0x58) { bmp280_read_calibration(); //setFilterCoefficient(kFilter_16x); INFO("Bosch Sensortec BMP280 ready"); } else { WARN("Bosch Sensortec BMP280 not found (chip ID=0x%02x, expected=0x58)", chip_id); } } // Calibration parameters stored on chip static uint16_t dig_T1; static int16_t dig_T2; static int16_t dig_T3; static uint16_t dig_P1; static int16_t dig_P2; static int16_t dig_P3; static int16_t dig_P4; static int16_t dig_P5; static int16_t dig_P6; static int16_t dig_P7; static int16_t dig_P8; static int16_t dig_P9; void Barometer::bmp280_read_cal_reg(const uint8_t reg, char* val) { *val = read_reg(reg); *(val + 1) = read_reg(reg + 1); } void Barometer::bmp280_read_calibration() { bmp280_read_cal_reg(0x88, (char*)&dig_T1); bmp280_read_cal_reg(0x8A, (char*)&dig_T2); bmp280_read_cal_reg(0x8C, (char*)&dig_T3); bmp280_read_cal_reg(0x8E, (char*)&dig_P1); bmp280_read_cal_reg(0x90, (char*)&dig_P2); bmp280_read_cal_reg(0x92, (char*)&dig_P3); bmp280_read_cal_reg(0x94, (char*)&dig_P4); bmp280_read_cal_reg(0x96, (char*)&dig_P5); bmp280_read_cal_reg(0x98, (char*)&dig_P6); bmp280_read_cal_reg(0x9A, (char*)&dig_P7); bmp280_read_cal_reg(0x9C, (char*)&dig_P8); bmp280_read_cal_reg(0x9E, (char*)&dig_P9); LOG("Calibration parameters: T=[%u, %d, %d] P=[%u, %d, %d, %d, %d, %d, %d, %d, %d]", dig_T1, dig_T2, dig_T3, dig_P1, dig_P2, dig_P3, dig_P4, dig_P5, dig_P6, dig_P7, dig_P8, dig_P9); } enum Oversampling { kSkip = 0, kOversample_1x = 1, kOversample_2x = 2, kOversample_4x = 3, kOversample_8x = 4, kOversample_16x = 5, }; // Time taken to read the pressure at a particular oversampling // cf. page 18 static float waitTime_ms[] = { 0, // skip 6.4, // 1x 8.7, // 2x 13.3, // 4x 22.5, // 8x 50, // 16x }; enum Filtering { kFilter_None = 0, kFilter_2x = 1, kFilter_4x = 2, kFilter_8x = 3, kFilter_16x = 4 }; void Barometer::setFilterCoefficient(const uint8_t iir) { write_reg(0xF5, (iir & 0x07) << 1); INFO("Filter coefficient => %dx", 1 << iir); } void Barometer::takeMeasurement(const uint8_t tmpovr, const uint8_t psrovr) { // Start a forced measurement write_reg(0xF4, ((tmpovr & 0x07) << 5) | ((psrovr & 0x07) << 2) | 0x01 /* force reading mode */); // wait until it's done //wait_ms(waitTime_ms[psrovr]); // XXX: what does this mean for BLE? } // These typedefs are for Bosch's conversion algorithms below typedef uint32_t BMP280_U32_t; typedef int32_t BMP280_S32_t; typedef int64_t BMP280_S64_t; // 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 static BMP280_S32_t t_fine; double bmp280_val_to_temp(BMP280_S32_t adc_T) { BMP280_S32_t var1, var2, T; var1 = ((((adc_T>>3) - ((BMP280_S32_t)dig_T1<<1))) * ((BMP280_S32_t)dig_T2)) >> 11; var2 = (((((adc_T>>4) - ((BMP280_S32_t)dig_T1)) * ((adc_T>>4) - ((BMP280_S32_t)dig_T1))) >> 12) * ((BMP280_S32_t)dig_T3)) >> 14; t_fine = var1 + var2; T =(t_fine*5+128)>>8; return T / 100.0; } // 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 double bmp280_val_to_pa(BMP280_S32_t adc_P) { BMP280_S64_t var1, var2, p; var1 = ((BMP280_S64_t)t_fine) - 128000; var2 = var1 * var1 * (BMP280_S64_t)dig_P6; var2 = var2 + ((var1*(BMP280_S64_t)dig_P5)<<17); var2 = var2 + (((BMP280_S64_t)dig_P4)<<35); var1 = ((var1 * var1 * (BMP280_S64_t)dig_P3)>>8) + ((var1 * (BMP280_S64_t)dig_P2)<<12); var1 = (((((BMP280_S64_t)1)<<47)+var1))*((BMP280_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 = (((BMP280_S64_t)dig_P9) * (p>>13) * (p>>13)) >> 25; var2 = (((BMP280_S64_t)dig_P8) * p) >> 19; p = ((p + var1 + var2) >> 8) + (((BMP280_S64_t)dig_P7)<<4); return ((BMP280_U32_t)p) / 256.0; } double Barometer::getPressure() { takeMeasurement(kSkip, kOversample_16x); const uint8_t msb = read_reg(0xF7); const uint8_t lsb = read_reg(0xF8); const uint8_t xlsb = read_reg(0xF9); const uint32_t val = (msb << 12) | (lsb << 4) | ((xlsb & 0xF0) >> 4); return bmp280_val_to_pa(val) / 100.0; } double Barometer::getTemperature() { takeMeasurement(kOversample_1x, kSkip); const uint8_t msb = read_reg(0xFA); const uint8_t lsb = read_reg(0xFB); const uint8_t xlsb = read_reg(0xFC); const uint32_t val = (msb << 12) | (lsb << 4) | ((xlsb & 0xF0) >> 4); return bmp280_val_to_temp(val); } double Barometer::getAltitude() { const double R = 287.05; // general gas constant const double g = 9.80665; // acceleration due to gravity const double T = 297.6; // supposed to be average temperature between p and p0 const double p0 = 1000.0; // hPa sea level const double p = getPressure(); const double h = (R / g) * T * log(p0 / p); return h; }