bmp280 datasheet

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Sensortec | BMP280 Data sheet
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Modifications reserved | Data subject to change without notice
Document number: BST-BMP280-DS001-23 Revision_1.23_11202
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Compensating the pressure value with 32 bit integer has an accuracy of typically 1 Pa (1-sigma). At
very high filter levels this adds a noticeable amount of noise to the output values and reduces their
resolution.
// 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
BMP280_S32_t t_fine;
BMP280_S32_t bmp280_compensate_T_int32(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;
}
// Returns pressure in Pa as unsigned 32 bit integer. Output value of “96386” equals 96386 Pa = 963.86 hPa
BMP280_U32_t bmp280_compensate_P_int32(BMP280_S32_t adc_P)
{
BMP280_S32_t var1, var2;
BMP280_U32_t p;
var1 = (((BMP280_S32_t)t_fine)>>1) – (BMP280_S32_t)64000;
var2 = (((var1>>2) * (var1>>2)) >> 11 ) * ((BMP280_S32_t)dig_P6);
var2 = var2 + ((var1*((BMP280_S32_t)dig_P5))<<1);
var2 = (var2>>2)+(((BMP280_S32_t)dig_P4)<<16);
var1 = (((dig_P3 * (((var1>>2) * (var1>>2)) >> 13 )) >> 3) + ((((BMP280_S32_t)dig_P2) * var1)>>1))>>18;
var1 =((((32768+var1))*((BMP280_S32_t)dig_P1))>>15);
if (var1 == 0)
{
return 0; // avoid exception caused by division by zero
}
p = (((BMP280_U32_t)(((BMP280_S32_t)1048576)-adc_P)-(var2>>12)))*3125;
if (p < 0x80000000)
{
p = (p << 1) / ((BMP280_U32_t)var1);
}
else
{
p = (p / (BMP280_U32_t)var1) * 2;
}
var1 = (((BMP280_S32_t)dig_P9) * ((BMP280_S32_t)(((p>>3) * (p>>3))>>13)))>>12;
var2 = (((BMP280_S32_t)(p>>2)) * ((BMP280_S32_t)dig_P8))>>13;
p = (BMP280_U32_t)((BMP280_S32_t)p + ((var1 + var2 + dig_P7) >> 4));
return p;
}