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CCS/TM4C129ENCPDT: Reset buttpn control

RAGHUL N M
Intellectual 490 points
Part Number: TM4C129ENCPDT


Tool/software: Code Composer Studio

Hi,

I am using TM4C129ENCPDT with code composer studio.

I have a requirement like I need to monitor the reset button of the board programmatically. Is it possible?

There is a Reset ISR in startup_ccs.c file. I tried adding UARTprintf statements inside that ISR assuming it works in bootup or when I press the reset button. It didn't happen since all the UART configuration are done in the main which will execute after Reset ISR. 

I need to monitor the press and release of the reset button and time interval between the press and release and do the decision making accordingly.

Thank you for your time.

  • 0
    TI__Guru**** 191886 points

    Hi,

     You can monitor the EXT bit in the Reset Cause register.

  • 0 in reply to Charles Tsai
    Intellectual 490 points

    Thanks, Charles for your Quick reply.

    The EXT bit in reset cause register gives me info regarding whether an external reset has occurred or not since the previous POR? Can I monitor the time between the press and release of EXT reset button like a normal tactile switch connected to a  GPIO input pin?

    Thank you for your time.

  • 0 in reply to RAGHUL N M
    TI__Guru**** 191886 points
    That is not possible. While the reset button is pressed the entire device is in reset. There is no circuit in the device that can measure the elapse time while the device is in reset. Why do you need to know the elapsed time? Do you have external circuit that can measure reset pulse?
  • 0 in reply to Charles Tsai
    Guru 117855 points

    This post was directed to the O.P. - (not) to Charles...

    While the MCU's 'Reset' is 'active' - it is effectively rendered, 'Deaf/Blind & Dumb.'

    You 'NEED' to 'Monitor the Reset Line' - yet such (need) is extremely rare - and is likely to 'prove so' - in your case as well.

    Both Vendor (Charles) and this outsider - see 'NO practical use for such 'Reset Monitoring Capability' - unless you are 'qualifying the MCU's Reset Behavior!'

    Instead - you SHOULD be able to substitute a 'normal' GPIO for the 'Reset' - and (easily) measure that GPIO.    Should you require an MCU Reset - as a response to such a 'Switch Actuation' - you may, 'Save your measurement to an external EEprom' and then command a Software Reset.'     (Note that 'Zero Case' has been made for the 'NEED' for such Reset - and especially for 'Measuring & Logging the 'Duration' of  Reset...)