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TL16C550C: INTRPT Pin is keep activated(high) and only a cold start can make it work again

kunpeng li
Prodigy 30 points
Part Number: TL16C550C

HI, my 16C550 is act abnormal sometimes,      it can only send data but can't receive data,  so I measured the INTRPT pin , and found , when the 16c550 can not receive data , the INTRPT pin is always activated(high) , when 16C550 is work normally , the INTRPT is like pulse signal.    so please help, I don't know why the INTRPT remain high, I set the IER register to 0x01 so I think only a received data that is available will make INTRPT go active, and it will reset after I read the buffer,   don't know why it will remain active, thanks 

the attachments is the waveform of INTRPT when everything is fine and when can not receive.

  • 0
    TI__Mastermind 47328 points

    Hi Kunpeng,

    What is the difference between the first and second scope captures? Are the two scope captures a picture of two separate instances of interrupts? The top one looks like the interrupt pin toggles on/off, on when receiving data, off when reading the FIFO. 

    You are asking why the interrupt stays on when the device is working. Are you transmitting data faster than you can read the data? The receiver buffer register may never be fully cleared and therefore the interrupt stays high until data is no longer available in the receiver buffer register or goes below the trigger level in FIFO mode. 

    Regards,

    Tyler