long countdown timer, how to save power?

[Darrel Taylor]

I think something like this would work. (untested)

<font color="#000000"><b>TMR1IF  </b><font color="#008000"><b>VAR </b></font><b>PIR1</b>.<font color="#800000"><b>0

</b></font><font color="#0000FF"><b><i>;Countdown from
</i></b></font><b>Years     </b><font color="#008000"><b>CON </b></font><font color="#800000"><b>0
</b></font><b>Days      </b><font color="#008000"><b>CON </b></font><font color="#800000"><b>30
</b></font><b>Hours     </b><font color="#008000"><b>CON </b></font><font color="#800000"><b>4
</b></font><b>Minutes   </b><font color="#008000"><b>CON </b></font><font color="#800000"><b>12

</b></font><b>TheCount  </b><font color="#008000"><b>VAR WORD</b></font>[<font color="#800000"><b>2</b></font>]

<font color="#008000"><b>ASM  
</b></font><font color="#000080">TotalSeconds = _Years*31536000 + _Days*86400 + _Hours*3600 + _Minutes*60
    MOVE?CW TotalSeconds &amp;&amp; 0xFFFF, _TheCount
    MOVE?CW TotalSeconds &gt;&gt; 16, _TheCount + 2
</font><font color="#008000"><b>ENDASM

</b></font><b>T1CON </b>= <font color="#800000"><b>%00001011                  </b></font><font color="#0000FF"><b><i>; T1 OSC ON, Timer ON

</i></b></font><b>Main</b>:
    <b>TMR1IF </b>= <font color="#800000"><b>0                     </b></font><font color="#0000FF"><b><i>; clear the Timers IF flag
    </i></b></font>@ <font color="#008000"><b>SLEEP
    </b></font>@ <b>NOP                        
    TheCount </b>= <b>TheCount </b>- <font color="#800000"><b>2        </b></font><font color="#0000FF"><b><i>; subtract 2 seconds
    </i></b></font><font color="#008000"><b>IF </b></font><b>TheCount </b>= <font color="#800000"><b>0 </b></font><font color="#008000"><b>THEN           </b></font><font color="#0000FF"><b><i>; if low Word is 0
        </i></b></font><font color="#008000"><b>IF </b></font><b>TheCount</b>(<font color="#800000"><b>1</b></font>) = <font color="#800000"><b>0 </b></font><font color="#008000"><b>THEN    </b></font><font color="#0000FF"><b><i>;   check high Word
            </i></b></font><font color="#008000"><b>HIGH </b></font><b>PORTB</b>.<font color="#800000"><b>0           </b></font><font color="#0000FF"><b><i>;   count complete, turn a pin on
            </i></b></font><font color="#008000"><b>STOP
        ENDIF  
        </b></font><b>TheCount</b>(<font color="#800000"><b>1</b></font>) = <b>TheCount</b>(<font color="#800000"><b>1</b></font>) - <font color="#800000"><b>1  </b></font><font color="#0000FF"><b><i>; not finished dec high Word
    </i></b></font><font color="#008000"><b>ENDIF
GOTO </b></font><b>Main
</b>

Make sure the WDT, VREF and anything that draws current is turned off.

HTH,
  DT