STM32F401 low temperature problem

[‪tsur.1]

Hi, I am using STM32F401CCU6 on my circuit and it working well at room temperature. When I was testing the circuit in low-temperature below -10 degrees the RX of UART1 lost messages, when I came back to 0 degrees the circuit is coming back to normal opera

[Tesla DeLorean]

If the design doesn't work properly in the intended environment you're likely going to have to respin it in a way that does.

Perhaps you can profile the HSI, LSI and internal temp and come up with a curve that works for most or specific devices.

Auto-bauding might be the easiest to implement. If bytes are sent in bursts you could profile the inter-symbol time between interrupts.

[‪tsur.1]

hi guys, thanks a lot for the help, I did calibrate the HSI, and the UART start working at -20 degree.

 The AN5067 Application note is very helpful for this case.

 I am still working on the calibration process with automation in the oven. 

I also read in the reference manual (RM0368) on page 101 that it's possible to make the calibration with the LSI clock and not just with LSE, is someone here know this method? 

[waclawek.jan]

LSI is an even less precise/stable RC oscillator than HSI, so I believe it's the other way round, LSE to be used as precise source to calibrate LSI.

JW