AN4631 datasheet(24/30 Pages) STMICROELECTRONICS

Part #	AN4631

Description	How to calibrate an STM32L0xx internal RC oscillator

PDF	30 Pages

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Manufacturer	STMICROELECTRONICS [STMicroelectronics]

Direct Link	http://www.st.com

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Internal oscillator measurement

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DocID027266 Rev 2

Internal oscillator measurement

The internal MSI and LSI RC oscillators are low-power and low-cost clock sources. In the

STM32L0xx microcontroller family, an internal connection is provided between the internal

RC oscillators (MSI and LSI) and the embedded timer (TIM21) to facilitate the measurement

procedure.

3.1

Measurement principle

The internal RC oscillator measurement procedure consists in running the timer counter

using the HSI16 clock, configuring the timer in Input capture mode and then connecting the

internal RC oscillator (that needs to be measured) to the timer.

The following figure shows the configuration used to perform the MSI measurement. As

shown, MSI can be connected internally to TIM21 Input 1 (TI1).

Figure 13. MSI measurement configuration

The next figure shows the configuration used to perform LSI measurement. As shown, LSI

can be connected internally to TIM21 Input 1 (TI1).

AN4631 Datasheet(PDF) 24 Page - STMicroelectronics