• State Resolved
  • Locked Locked
  • Replies 3 replies
  • Answers 1 answer
  • Subscribers 99 subscribers
  • Views 290 views
  • Users 0 members are here
Support feedback
Options
Options
Related

This thread has been locked.

If you have a related question, please click the "Ask a related question" button in the top right corner. The newly created question will be automatically linked to this question.

Original question:

AM6442: About UART mode.

AM6442: About UART mode

tomitama
Expert 1090 points

Part Number: AM6442

question 1
About the chapter "1.5.4.8.1.3.7.1 Time-Out Counter" of TRM.
  Please tell me a specific example of setting the timeout time.
  For example, if the baud rate is 115200, how long does the receiver line (RX) stay high before it times out?

Question 2
About the TRM chapter "12.1.5.4.7.1 Register Access Modes".
  After setting the register access mode, does the software need to wait for the setting to be completed?
  Is it possible to access registers in the changed access mode even if there is no DSB (Data Sync Barrier) after setting the register access mode?

  • 0
    TI__Mastermind 29945 points
    tomitama said:
    question 1
    About the chapter "1.5.4.8.1.3.7.1 Time-Out Counter" of TRM.
      Please tell me a specific example of setting the timeout time.
      For example, if the baud rate is 115200, how long does the receiver line (RX) stay high before it times out?

    The chapter references states:

    An RX idle condition is detected when the receiver line (RX) is high for a time that equals 4x the programmed
    word length + 12 bits or manually configured amount of baud clocks, if a value other zero is set in the timeout
    register. RX is sampled midway through each bit.

    tomitama said:
    Question 2
    About the TRM chapter "12.1.5.4.7.1 Register Access Modes".
      After setting the register access mode, does the software need to wait for the setting to be completed?
      Is it possible to access registers in the changed access mode even if there is no DSB (Data Sync Barrier) after setting the register access mode?

    The programming guide in the TRM does not require a delay after programming the UART_LCR register.

    The UART_LCR register should be set to operational mode for operation. Operational mode must be disabled in order to switch to Config mode A or B.

    --Paul

  • 0 in reply to PaulM
    Expert 1090 points

    Thank you for your reply.

    I didn't understand the answer to Question 1, so I'll ask again.

    If the word length is 8 bits and the timeout register is 0 bytes,
    Does it time out when the receiver line (RX) becomes HI for 44 bits in a row?
    (8bit x 4) + 12bit = 44bit

    If the timeout register is 10 bytes (80 bits),
    Does it time out when the receiver line (RX) becomes HI for 80 bits in a row?

    Also, when does the time-out occur when the receiver line (RX) becomes HI continuously from what timing?

  • +1 in reply to tomitama
    TI__Mastermind 29945 points
    tomitama said:
    Does it time out when the receiver line (RX) becomes HI for 44 bits in a row?
    (8bit x 4) + 12bit = 44bit

    Correct

    tomitama said:
    If the timeout register is 10 bytes (80 bits),
    Does it time out when the receiver line (RX) becomes HI for 80 bits in a row?

    The TIMEOUTL/H  register can be used as an override of the default calculation. The 16-bit value represents the number of baud clocks for the timeout.

    Yes, if TIMEOUT is programmed for 80, and the is no RX activity, then a timeout will occur..

    tomitama said:
    Also, when does the time-out occur when the receiver line (RX) becomes HI continuously from what timing?

    I believe the timeout counter starts once no activity is seen on the RX line. Any activity on the RTX line will reset the timeout counter. 

      --Paul