RCC internal clock sources calibration register 3
| HSICAL | HSI clock calibration These bits are initialized at startup with the factory-programmed HSI calibration trim value. When HSITRIM is written, HSICAL is updated with the sum of HSITRIM and the factory trim value. |
| HSITRIM | HSI clock trimming These bits provide an additional user-programmable trimming value that is added to HSICAL[11:0] bits. It can be programmed to adjust to voltage and temperature variations that influence the frequency of the HSI. |