Interrupt Service Routine (continued)

• //------------------------------------------------
• // increment a count of 12 samples in 10msec
• // 12*1/1200 sec = 1/100 sec
• //------------------------------------------------
• tick12Count++;
• //------------------------------------------------
• // if 10msec passed, increment legacy 10msec counter
• //------------------------------------------------
• if (tick12Count >= 12) {
• tickCount++;
• tick12Count = 0;
• if (--tickHelper == 0) {
• tickHelper = TICKS_PER_SECOND;
• tickSec++;
• }
• }
• //------------------------------------------------
• // Set ADC to convert newly selected input
• // to be read upon next ISR
• //------------------------------------------------
• ADCON0_ADON = 1;
• ADCON0_GO = 1;

• The Modtronix web server has a 10msec “tickCount” counter
• This corresponds to 12 interrupts at 1200Hz, so increment a tick12Counter every interrupt

• Everytime tick12Counter passes 12, reset it, and count the legacy “tickCount”

• Last thing we do in the ISR routine is to trigger the A/D converter to take another measurement