We bought a number of BMP388s and they showed bad accuracy and drift in pressure output. I asked customer support for the issue and she found some calibration coefficients in NVM must be wrong. I tried to check the calibration coefficients in NVM using a spread sheet which Bosch customer support gave to us. The result is as below.
| Calculation of pressure and temperature for BMP388 |
| | | | | |
| | | | | |
| | Input Calibration Parameters | Quantization Factor | Quantized | |
| DO_C | 27322 | 0.00390625 | 6994432 | NVM_PAR_T1 |
| DTK1_C | 18880 | 1073741824 | 1.758E-05 | NVM_PAR_T2 |
| DTK2_C | -10 | 2.81475E+14 | -3.553E-14 | NVM_PAR_T3 |
| | | | | |
| O_C | 25371 | 0.125 | 202968 | NVM_PAR_P5 |
| TK1O_C | 30991 | 64 | 484.23438 | NVM_PAR_P6 |
| TK2O_C | -13 | 256 | -0.0507813 | NVM_PAR_P7 |
| TK3O_C | -10 | 32768 | -0.0003052 | NVM_PAR_P8 |
| | | | | |
| S_C | 395 | 1048576 | -0.0152483 | NVM_PAR_P1 |
| TK1S_C | -2608 | 536870912 | -3.538E-05 | NVM_PAR_P2 |
| TK2S_C | 35 | 4294967296 | 8.149E-09 | NVM_PAR_P3 |
| TK3S_C | 0 | 1.37439E+11 | 0 | NVM_PAR_P4 |
| | | | | |
| NSL_C | 16342 | 2.81475E+14 | 5.806E-11 | NVM_PAR_P9 |
| TKNLS_C | 29 | 2.81475E+14 | 1.03E-13 | NVM_PAR_P10 |
| NLS3_C | -60 | 3.68935E+19 | -1.626E-18 | NVM_PAR_P11 |
| | | | | |
| | 24 Bit | 21 Bit | | |
| ADCT | 9543040 | | | |
| ADCP | 8652032 | 1081504 | | |
| | calculated | | Read | |
| Temp | 44.58235492 | [°C] | 44.582 | [°C] |
| p | 82631.0904 | [Pa] | 826.311 | [hPa] |
The symptom is mostly the same in all BMP388 that we bought. We thought that correction of wrong parameters above would improve the accuracy of sensing air presure but Bosch sensortec said they would not support for the issue anymore. Does anyone find an incorrect parameter on this spread sheet? Does anyone know how to derive correct calibration coefficients for each BMP388? Thank you very much in advance.
