The WDT timer is a simple RC timer with a typical
time-out period of about 18 ms. This time-out period is
dependent on Voltage, Temperature and Silicon pro-
cess variations. Hence the tolerance on the time-out
period is very wide: Min. of 9 ms to a Max. of 33 ms
(please refer to appropriate datasheet for device
dependent value). There are applications where an
additional timer would be useful as an approximate
time keeper, hence getting a more precise value of the
WDT time-out is useful. This Tech Brief implements an
automatic calibration of the WDT time-out period on
start-up. TB004
Automatic Calibration of the WDT Time-out Period
CONCLUSION
Author: Stan D’Souza
Advanced Microcontroller The calibration of the WDT is simple and takes very lit-
Technology Division tle overhead in a program. The code in Appendix A is
written for a PIC16C84 device, but can be translated to
work on any PIC16CXXX product. The code in
Appendix B is writt……
