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Reliable U(S)ART between two STM32 MCUs with internal oscillator

Question asked by T B on Sep 15, 2017
Latest reply on Sep 15, 2017 by Clive One



I have a best practice question.


Correct UART communication requires the transmitter and receiver clocks differ by less than 5% (2.5% per MCU), otherwise communication errors may occur. For the temperature range TA = 0 to 85°C the Accuracy of the HSI oscillator is good enough. But for temperatures below 0°C, the HSI has too less accuracy.


What do you do?
•    Use external oscillator
•    Use autobaud detection.
•    Oscillator calibration with external signal
•    Do not care
•    ….