External Watch Dog Timer

• In websrv65_v310/src/mxwebsrvr.c
• Put this in TWO places:
• In the main() initialization section before the infinite while(1) loop
• In the interrupt HighISR() loop where it’ll be repeated 1200 times a second
• //-------------------------------------------------
• // Normal external watchdog timer state
• // Make RC0 = input & RC0 = 1
• //-------------------------------------------------
• TRISC = 0xff;
• LATC0 = 1;

• Everytime we process an ADC variable macro found on a fetched webpage, pull the line to the external watch dog timer

• In main initialization and 1200 Hz ISR routine, return the line to the external watch dog timer to idle state

• In websrv65_v310/src/cmd.c
• /////////////////////////////////////////////////
• //ADC variables
• else if (tagGroup == VARGROUP_ANALOG)
• {
• if (tagVal < 40)
• pGetTagInfo->ref = cmdGetWordVar(ref, pGetTagInfo->val, AdcValues[tagVal]);
• TRISC = 0; // set tickle line to output to external WDT
• LATC0 = 0; // set tickle line low to discharge external WDT
• return 1; //One byte was written
• }

• The instructions will permit the program to run without WDT reset only as long as it continues responding to webpages containing ADC macros on a periodic basis. If there is any lapse, the WDT will pull the reset line to the PIC.