This is a real-time PIC In-Circuit Emulator (ICE), programmer, debugger, and development system.

This project combines Microchip’s MPLAB development software with the advanced self-debugging features of the latest PIC chips. The result is a user-friendly advanced development system for a very low cost.

One way of testing programs relies on advanced software that can "run" in a virtual chip on a PC screen and advanced hardware which communicates with the program in the PC, reads input pins, and switches output pins to match the levels of the virtual chip. Such a system is called an In-Circuit Emulator or "ICE" and professional systems are available for practically every type of microcontroller.

The problem with this is cost. A professional ICE for the PIC series of chips costs a reasonable 2000 UK Pounds or so. Not a lot if you are a professional programmer, but certainly enough to make your eyes water if you are an amateur!

Just lately a new type of development system has appeared called In-Circuit Debugging (ICD). This requires a chip with special built in hardware (known as a "Background Debugger") and software which can communicate its status via a serial link.

The chip is fitted to its working printed circuit board (PCB) and all external hardware is connected and active. Code is then programmed, run, and debugged under PC control, until it is running correctly. For Microchip PIC users, the good news is that the PIC16F877 and its close relatives the ’876, ’874, and ’873 have built in ICD facilities and can be used to develop code which can be run in these and smaller chips in the range – such as the most popular PIC16F84.

This article is intended as an easy introduction to ICD with very simple demonstration programs, users can then progress to using the more complicated features of the chips.