AN4631 Datasheet, PDF (14/30 Pages) STMicroelectronics – How to calibrate an STM32L0xx internal RC oscillator

Internal RC oscillator calibration
Figure 8. Internal oscillator calibration: finding the minimum frequency
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1. If the system clock source is HSI16, the trimming bits have a 5-bit length and the number of steps is 32. If
the system clock source is MSI, the trimming bits have an 8-bit length and the number of steps is 256.
2. Frequency measurement is detailed in Section 2.3.5.
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