Reset

POR

During the work of microcontroller, supply voltage variations occurs. It is very dangerous if voltage drops beneath certain limit, because microcontroller can make some unpredictable actions. In the case of such

voltage drop detection, microcontroller is switched into Power on Reset mode in which it remains until voltage stabilizes above critical limit which is defined by Trip Voltage parameter.

XRES

External reset allows user to bring microcontroller to start state by switching a button. Reset is achieved when XRES pin reads logic ONE. Simplest reset circuit can be made with pull-down resistor and one switch.

WDR

Watch dog reset (WDR) is used for avoiding software dead-loops or other irregularities, bringing the system in the start state. Using WDR, it is watch dog timer (WDT) is periodically restarted inside of a main program, after which appropriate subprograms are executed. In normal mode after certain time WDT is being restarted once again and subprogram cycle continues. But, if program blocks in one of the subprograms WDT is not reset, and WDR occurs.