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reset after enabling usci- uart

Jeff Cartwright
Prodigy 60 points

Hey so i have been stuck on this problem for some time now. I have been converting code from the f449 to the fg4619. part of this was changing the usart to a usci- uart. I set up the baudrate and registers and after i enable the usci using ucswrst the board will reset while waiting for a response. after it resets the wdtifg will be set but I have had the wdt disabled the whole time... If i run the code with out enabling the usci then the board will not reset, it will just time out waiting for a response.

thank you in advance for any help

  • 0
    Guru 227245 points

    USART interrupts are edge-triggered- Once your ISR responded to an interrupt, it is gone.
    USCI  interrupts are level-triggered. So as long as the interrupt condition still exists, your ISR will be entered and entered again, effectively halting the main function and finally causing a watchdog reset.

    To stop an USCI uart, you must remove the cause of the interrupt. This means either writing/readign the proper buffer, manually clearing the IFG bit or disablign this interrupt by clearing the IE bit. If you don't do one of the three, the interrupt condition remains and your ISR will called over and over again.

  • 0 in reply to Jens-Michael Gross
    Prodigy 60 points

    the thing is the USCRXIE interrupt vector is never fired, could it still be stuck even if it never runs though the interrupt vector?  its reseting about the point in the code where the URXIFG0 interupt would fire for the old board.

  • 0 in reply to Jeff Cartwright
    Guru 227245 points

    Jeff Cartwright said:
    the thing is the USCRXIE interrupt vector is never fired, could it still be stuck even if it never runs though the interrupt vector?  its reseting about the point in the code where the URXIFG0 interupt would fire for the old board.

    I don't know your code. So I cannot say what's happening (or not).. If you could post the code.

    What I can tell as a generic hint is that the TXIFG bit is set after a device reset, so as soon as you set the UCTXIE bit, the TX ISR wil be called. If you don't write something into TXBUF, clear TXIFG or clear TXIE, it will enter the same endless ISR loop. Without knowing you rcode (at least USCI init, clock init and ISRs - and the actual MSP you're workign with) I cannot help you further.

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