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(Serial Interface) What is the formula for computing UART transfer bit rate? [2005/04/12]

最新更新:04/12/2005

Question:

(Serial Interface)  What is the formula for computing UART transfer bit rate? [2005/04/12]

Answer:

  • When using the internal clock for the synchronous clock
    Transfer bit rate (bps) =                            f (  XIN  )                       
    ( BRG setting value + 1 )  × 16  ×  m
     
    m : BRG count source select bit = When "0", m = 1
      BRG count source select bit = When "1", m = 4
     
    Main clock f(XIN) frequency range varies depending on the operating voltage.
     
  • When using external clock as synchronous clock
    Transfer bit rate ( bps ) = f ( SCLK ) / 16

    Please consider timing requirements regarding external clock frequency f(SCLK).
    A value which satisfies the minimum time specified in tc (SCLK) must be set.
    Refer to the electrical characteristics in the datasheet for timing requirements.

(#105191)

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