Below -15℃, UART Cant Receive any data (STM32WLE5CCU6)

[taowa0550]

When temperature below -15℃ , STM32WLE5CCU6 UART can't  receive any data from uart, But it can send data out from UART.,and The LoRa Unit worked well,It seems the TXCO is working. What's the problem? How can solve this problem?

[unsigned_char_array]

What happens exactly? Is no data send? Or is the baudrate of the data send invalid? Please use a logic analyzer or oscilloscope to check the TX pin.
If sending works, but receiving doesn't it still is sensible to check TX baudrate, because if clock changes both RX and TX are affected (but the receiving device may be more tolerant for baudrate errors).

Do you use internal clock er external? Internal clock can change significantly with temperature. This can cause baudrate errors.

[abbas78]

It's likely a hardware-related issue rather than a software or clock source issue (since LoRa is working, the TCXO appears fine).

[Andrew Neil]

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@taowa0550 wrote:

When temperature below -15℃ , STM32WLE5CCU6 UART can't  receive any data from uart, 

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What is the 2nd UART ?

As @unsigned_char_array said, are you sure that the other UART is still sending ?

Check the actual baud rates of both UARTs - are they drifting with temperature?

Does the STM32WL UART flag any errors; eg, Framing ?

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@taowa0550 wrote:

It seems the TXCO is working. 

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You mean TCXO ?

Is that actually related to the UART at all ?

PS:

Does  the other UART receive anything transmitted by the STM32WL ?

[taowa0550]

  The reason has found out ,   Because  the Uart  use internal RC oscillator, when temperature changed and  RC oscillator  frequency drift.  Thanks for All

[Andrew Neil]

Glad you found it.

Yes, that is to be expected when using an RC oscillator as a UART baud date clock.

If that's resolved the issue, please mark the solution:

https://community.st.com/t5/community-guidelines/help-others-to-solve-their-issues/ta-p/575256

#RCOscillator #BaudRate #RCOscillatorBaudRate