Without resetting....Switching PIC over to Backup Battery

[ScaleRobotics]

Hi financecatalyst,
If you can suffer a .7 volt drop, why not just use 2 diodes, one on the battery and 1 on the mains fed supply, the pic will draw from whichever is outputting the highest voltage. No reset. as for the other stuff, sense the mains fed supply with an analog port, or heck even a digital port (if power then main loop) and jump to the disabled routine if not true.

The January 2011 Nuts and Volts magazine shows a simple example using exactly that. They let people embed it into blogs and such, but I am not sure it will be visible without a subscription.

<table border="0" cellpadding="0" cellspacing="0"> <tbody><tr style="background-color: rgb(210, 210, 210); height: 30px;"> <td><img class="navlogo" src="http://n-cdn.dashdigital.com/nutsvolts/include/icons/navbar_logo.gif?lm=1292898564000" alt="Nuts &amp; Volts" align="left" height="28"> </td> <td style="color: rgb(102, 102, 102); font-weight: bold; font-family: tahoma,sans-serif; font-size: 11px; line-height: 15px; padding-right: 5px;" align="right"> <span id="top_right_text">Look inside &gt;</span> </td> </tr> <tr style="background-color: rgb(255, 255, 255);"> <td colspan="2" style="padding: 10px 0px;" align="center"> <a href="http://nutsvolts.texterity.com/nutsvolts/201101?pg=41" target="_blank" onclick="window.open('http://nutsvolts.texterity.com/nutsvolts/201101?pg=41','sharewidget','toolbar=no,menubar=no ,resizable=yes,scrollbars=yes,left=0,top=0,width=' +(screen.width-10)+',height='+(screen.height-10)+'');return false;" title="View Magazine"> <img src="http://n-cdn.dashdigital.com/nutsvolts/201101/data/imgpages/smtn/0041_wdxmxd.gif?lm=1292898564000" alt="41" border="0"> </a> </td> </tr> <tr style="background-color: rgb(210, 210, 210); height: 30px;"> <td colspan="2" style="color: rgb(102, 102, 102); font-weight: bold; font-family: tahoma,sans-serif; font-size: 11px; line-height: 15px;" align="center"> <span id="bottom_text">January 2011</span> </td> </tr> </tbody></table>