# task in PIC16f887 with watchdogtimer

Can someone help how to find formula and calculate this task?

How many times per second will be reset if the microcontroller is set to 1:128 preskaler microcontrollers and works on Frequency of 8 Mhz.

Could someone explain me how to solve this kind of task? Please.

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On the '887 you have 2 prescalers on the watchdog - the dedicated 16-bit watchdog prescaler, and the secondary prescaler shared with Timer0. Are you using the secondary one at all, or just the watchdog one? –  Majenko Nov 30 '11 at 17:57
just watchdog one –  jiki Nov 30 '11 at 18:00

The watchdog always runs from the internal 31KHz internal oscillator.

The general formula for calculating the watchdog time is:

$\frac{1}{31000}\times WDTPrescaler [\times Prescaler]$

Where $WDTPrescaler$ is the dedicated 16-bit watchdog prescaler, and $Prescaler$ is the optional 8-bit prescaler shared with the Timer0 module.

$\frac{1}{31000}\times 128 = 0.004129032$