Hi,
Thanks for the replay.
Yes, I do see absolute accuracy pressure errors of about 4hPa.
I checked the issue on 5 different sensors. I used as reference two iPhones as well as a website that reports real time local presure.
I can't send the full code it is few 100K lines of code. The relevant code is below.
#define CntrlMeasDefault 0B10110111 //Temp OS 16X, Press OS 16x, Power Normal
#define ConfigDefault 0B01010000 //Inactive 125ms, IIR Filter coefx16, SPI OFF
s32 IS_BMP_Config()
{
s32 com_rslt = ERROR;
u8 CntrlMes=CntrlMeasDefault;
u8 Config= ConfigDefault;
I2C_routine(); // Initiate a pointer to the I2C routine
com_rslt = bme280_init(&bme280); // Read DeviceID and the compensation parameters.
com_rslt=bme280_write_register(BME280_CTRL_MEAS_REG,CntrlMes,(u8)1);
com_rslt+=bme280_write_register(BME280_CONFIG_REG,Config,(u8)1);
HAL_Delay(100);
Read_Config_Reg();
return com_rslt;
}
s32 Get_BMP280_Bridge_Data(s32 *v_data_uncomp_temp_s32 ,s32 *v_data_uncomp_pres_s32)
{
s32 com_rslt = BME280_INIT_VALUE;
com_rslt = bme280_read_uncomp_temperature(v_data_uncomp_temp_s32);
com_rslt += bme280_read_uncomp_pressure(v_data_uncomp_pres_s32);
return com_rslt;
}
double IS_Compensate_Pressure(s32 v_uncomp_pressure_s32)
{
double var1, var2;
int8_t rslt=BMP280_OK;
double pressure=0;
//rslt = null_ptr_check(dev);
if (rslt == BMP280_OK)
{
var1 = ((double) p_bme280->cal_param.t_fine / 2.0) - 64000.0;
var2 = var1 * var1 * ((double) p_bme280->cal_param.dig_P6) / 32768.0;
var2 = var2 + var1 * ((double) p_bme280->cal_param.dig_P5) * 2.0;
var2 = (var2 / 4.0) + (((double) p_bme280->cal_param.dig_P4) * 65536.0);
var1 = (((double)p_bme280->cal_param.dig_P3) * var1 * var1 / 524288.0 + ((double)p_bme280->cal_param.dig_P2) * var1) /
524288.0;
var1 = (1.0 + var1 / 32768.0) * ((double) p_bme280->cal_param.dig_P1);
pressure = 1048576.0 - (double)v_uncomp_pressure_s32;
if (var1 < 0 || var1 > 0)
{
pressure = (pressure - (var2 / 4096.0)) * 6250.0 / var1;
var1 = ((double)p_bme280->cal_param.dig_P9) * (pressure) * (pressure) / 2147483648.0;
var2 = (pressure) * ((double)p_bme280->cal_param.dig_P8) / 32768.0;
pressure = pressure + (var1 + var2 + ((double)p_bme280->cal_param.dig_P7)) / 16.0;
}
else
{
pressure = 0;
rslt = BMP280_E_DOUBLE_COMP_PRESS;
}
}
return pressure;
}
/*
* returns altitude in meters based on pressure and standard seaLevelpressure, both in hPa
* standard seaLevelhPa = 1013.25
*/
float Get_Altitude(float Pressure)
{
return (float)44330 * (1.0 - pow(Pressure / 1013.25, 0.19026)); // From feet converted to [M]
}
