Internal RC oscillator calibration

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DocID027266 Rev 2

Figure 6. Hardware connection using LSE as the reference frequency

In the above figure:

TI1_RPM: TIM21 input 1 remapping

TI1_RPM: Timer input 1

IC1PS: Input capture 1 prescaled

2.2.2

Case where another source is used as the reference frequency

Any signal with accurate frequency can be used for internal oscillator calibration, and the

mains is one of the possibilities.

As shown by Figure 7 below, the reference signal should be connected to Timer 21

channel 1.

Figure 7. Hardware connection using external reference frequency

In the above figure:

TI1_RPM: TIM21 input 1 remapping

TI1: Timer input 1

IC1PS: Input capture 1 prescaled

*PA2 and PB13 can be used as TIM21 channel 1