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AM3352: Effects of noise for UART peripheral

Junpei Kishi
Intellectual 865 points

Part Number: AM3352

Hi Team,

I want to know the effects for UART peripheral which are caused by two type noise signals.

1. Very short spike noise

Is there some effects for UART peripheral when RX pin receive very short spike noise like 1~2 us which is enough shorter than UART baud time?

I have two expected situation, one is that no effect were caused in this case, the other is that the peripheral mistake the noise for a start bit.

2. Longer spike than 1 baud time

In our case, we run the peripheral in 57600 baud, so the baud time is 17.6 us.

If the noise pulled down UART_RX for longer than 17.6 us, what's happen on the peripheral.

I think it's misidentified as a start bit.

Please let me know it is correct or not which shows above.

Thank you,

Junpei

  • 0
    TI__Mastermind 30695 points

    Junpei

    I have forwarded you questions to the design team and hope to have a response Monday, if not before. 

    --Paul 

  • +1
    TI__Mastermind 30695 points

    1. Very short spike noise

    The UART peripheral samples the incoming characters at the midpoint after being synchronized with the start bit falling edge.   If noise coincides with the sample point then the character could be read incorrectly.

    2. Longer spike than 1 baud time

    Similar to the previous question, this would result in an incorrect character being captured.

    The best approach would be to identify and eliminate the noise source. If not possible can the connection/cable connecting the UARTs be shielded?

    --Paul