Internal RC oscillator calibration

AN4067

14/27

DocID022913 Rev 2

3.3.1

Internal oscillator calibration with minimum error

The HSI_CalibrateMinError() function calibrates the internal oscillator (HSI) to have

the frequency nearest to the typical value. It measures all frequencies for different trimming

values and provides the trimming value that corresponds to the frequency with the minimum

error. The trimming value thus obtained is programmed in the trimming bits.

After calibration, the HSI_CalibrateMinError() function returns the internal oscillator

frequency value as an unsigned 32-bit integer (uint32_t).

The flowchart in Figure 10 provides the algorithm for this function.

Example

uint32_t InternOscAfterCalib = 0;

{

......

/* Get the internal oscillator (HSI) value after calibration */

InternOscAfterCalib = HSI_CalibrateMinError();

}

In case of an HSI14 calibration, the HSI14_CalibrateMinError() function should be used

instead of HSI_CalibrateMinError().