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Original question:

ISO3082: Signal Output Anomaly On Rx pin

ISO3082: hardware issus

albert qiu
Intellectual 330 points
Part Number: ISO3082

Hi TI expert

MCU data is sent to ISO3082 through UART3_TXD. After data is sent, DIR3 changes from high level to low level and switches to RX mode.
You will find that UART3_RXD has some abnormal data (485_1_B and 485_1_B have no data).
If you switch directions after 50ms, there is no abnormal data.
Is this phenomenon normal? How can we solve this problem

  • +1
    TI__Mastermind 29375 points

    Hello Albert,

    Thank you for reaching out. It looks like the DE transitions low at the exact same time that the TX data transmission ends. I suspect that the device is switching to receive mode before too soon and the signal is just finishing on the bus as a result of the propagation delay. 

    I would recommend waiting to switch modes until after about 3us (this is 2*Tplh(max)). 

    I hope this helps. 

    Best,
    Andrew