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UART can not receive at lower temperature

Hitoshi Sugawara
Mastermind 19960 points
Part Number: CC1310

Hi Experts,

A customer has confirmed that UART data can not be received when the temperature is low.
Result: 
      115200 baud
      Sent 28 data, CC1310 received 28 data with no problem. at 20 deg.C.  
      Sent 28 data, CC1310 received 0 data at 10 and 0 deg.C.

      9600 and 4800 baud
      Sent 28 data, CC1310 received 28 data with no problem. at 20 and 10deg.C.  
      Sent 28 data, CC1310 received 0 data at 0 deg.C.      received 9 data at 0 deg.C (4800baud)

      2400 baud
      Sent 28 data, CC1310 received 28 data with no problem. at 20 and 10deg.C
      Sent 28 data, CC1310 received 26 data at 0 deg.C.

      1200 and 600 baud 
      Sent 28 data, CC1310 received 28 data with no problem. at 20 deg.C, 10deg.C and 0 deg.C
      Sent 28 data, CC1310 received 0 data at -10 deg.C.

The external Xtal 24MHz is utilized.
They don't check the error bits.
Have you ever heard that condition before?
We would like to have your advice what they have to check?

Thank you for your check.
Best regards,
Hitoshi

  • 0
    TI__Guru**** 317180 points

    This is not a known condition. Generally, transistors are faster for lower temperature meaning that if the UART link was temperature dependent I would have expected issues for high temperatures and not low.

    How is this test done? Is it possible to post a picture that show the setup? 

  • 0 in reply to TER
    TI__Mastermind 19960 points

    Hi TER,

    Thank you for your feedback.
    Let me work with the customer and ask to share the picture for the setup.
    will get back to you ASAP.

    Best regards,
    Hitoshi

  • 0 in reply to Hitoshi Sugawara
    TI__Mastermind 19960 points

    Hi TER,

    The system consists of two CC1310 and UART communication runs between them.
    It seems UART data drops intermittently in lower temperature. 

    If you have any better idea to determine the root cause, it would be very appreciated.

    The customer will keep on communicating on this thread.

    Thank you for your kind support.
    Best regards,
    Hitoshi



  • 0 in reply to Hitoshi Sugawara
    TI__Guru**** 317180 points

    I did a quick test: I programmed two CC1310 Launchpads with the UARTECHO example and removed the TxD jumper on one board and the RxD jumper on the second board and connected a wire between the RxD and TxD. In addition I had a wire between the gnd pins to ensure that the two boards operate on the same gnd level. I tested on -10 degrees, -20 degrees, -30 degrees and I was able to send the UART chars from one board to the other for all. 115.2 kbaud was used.