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CCS/TMS320F28069: Watchdog timer calculation

Devvrat Arya56
Prodigy 110 points
Part Number: TMS320F28069


Tool/software: Code Composer Studio

I am using watchdog in my application. I have set the prescaler to the highest (0x7). Then watchdog is supposed to reset at around 36ms  (calc. below)  but according to CPU timer it resets around 850 msec. Am I calculating the values wrong?

Calc:

=> Calculated:    OSCLK/512/64= (90x10^6)^-1 x 512 x 64= 0.0036 (SYSCLK=90mHZ)

=> Actual:           850msec

The OSCLKSRC is the internal oscillator

  • 0
    TI__Guru 61235 points

    Devrat,

    The WD runs off the internal 10 MHz oscillator, not SYSCLKOUT.  Also, the counters themselves consist of the free-running counter (prescaler) that you have set to count to 64, and the 8-bit counter which always counts to 256.

    So, the calculation is:

    (1/10 MHz)*512*64*256 = 0.839 sec.

    Regards,

    David