AN2822

Conclusion

Doc ID 14983 Rev 2

17/19

3

Conclusion

The calibration method described in this application note, ensures that the high speed

internal clock of the STM8S and STM8A microcontrollers operates at its intended frequency

(16 MHz) in the target application, independently of the temperature and power supply

voltage drift.

The proposed solution uses the 16-bit timer TIM3 for measuring the internal RC oscillator

frequency and external calibration signal which can be easily adapted from the mains. An

implementation example with power supply and calibration signal conditioning circuit is

proposed.

The example source code written in ANSI C and using the STM8S and STM8A firmware

library can be download from www.st.com.