Hi,

It's just a passive board, with a single female header on one side and two mail headers on top

Name: easytest-board_1.jpg Views: 1161 Size: 27.1 KB

I think I've discovered what was happening. Looking at the schematic for the RTC2 add-on board there is an SQW pin which outputs a square wave that can be used as an interrupt... when this is plugged into the header on the EasyPIC5 board this SQW pin on the header connects to PORTC.2, hence the regular pulsing.

I didn't twig that this issue only rose it's head when I chose to use external LEDs to see what was happening as the status display LEDs for C1 and C2 on the EasyPIC5 board are covered by the 4 x 20 LCD. So much wasted time, and my apologies for wasting your time trying to troubleshoot a non-code related issue