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Internal oscillator measurement

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Figure 14. LSI measurement configuration

After enabling the timer counter, when the first rising edge of the internal oscillator signal to

be measured occurs, the timer counter value is captured and then stored in

IC1ReadValue1. On the second rising edge, the timer counter is captured again and stored

in IC1ReadValue2. The elapsed time between two consecutive rising edges of the clock

represents an entire period. The following figure shows the timing diagram of an internal RC

oscillator measurement.

Figure 15. Timing diagram of an internal RC oscillator measurement

The internal oscillator frequency value is computed as shown by the following formula:

internal oscillator frequency = HSI16_Value / Capture

where:

•

HSI16_Value is the HSI16 frequency value: typical value is 16 MHz,

•

Capture represents an entire period of internal RC oscillator (MSI or LSI):

IC1ReadValue2 - IC1ReadValue1.