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LED Chaser for PIC16F84A and 16F628A

This simple circuit functions as a 12 LED chaser.  A single illuminated LED 'walks' left and right in a repeating sequence, similar to the effect seen on KITT, the car in the Knight Rider TV series.
Fully commented source code and programmer ready HEX files are provided for the PIC 16F84A and 16F628A at the bottom of this page.
The circuit has been constructed on a PCB but can easily be built on strip-board, or a solderless breadboard.
This project has been put together for anyone starting with their first PIC and the source code is heavily commented with references to the PIC datasheets and the MPASM assembler user guide.

Schematic small view
Download schematic in PDF

PCB Layout
PCB artwork and overlay small view
Download PCB artwork in PDF
Download Eagle 5.02 CAD Files (ZIP)
Construction notes:
LED Chaser PCB copper side Fig.1 LED Chaser PCB assembled Fig .2 LED Chaser PCB without crystal or load capcitors fitted Fig. 3
In Fig 1. note how the holes for the DC Power Jack (top right) have been milled into slots to accept the solder tabs on the connector.  
You can use either a PIC 16F84A or PIC 16F628A microcontroller with this circuit.  Download the files required below.
The HEX files are ready to program straight into the PIC.  The asm files are the source code which you can modify or just view to see how it works.  If you are going to modify the code I recommend you download and install the Microchip MPLAB IDE which will allow you to edit, modify and program the PIC seamlessly.
If you need a PIC Programmer I strongly recommend the Microchip PICKit 2, this is available from suppliers world wide or direct from Microchip.  It's reasonably cheap to buy and reliable.  I have a couple of them and I wouldn't use anything else now.
Description Filename Download link
Source code for 16F84A ledchaser16F84A.asm download
HEX file ready to program into the PIC ledchaser16F84A.HEX download
Source code for 16F628A ledchaser16F628A.asm download
HEX file ready to program into the PIC ledchaser16F628A.HEX download
Microchip MPASM User Guide 33014J.pdf download
16F628A datasheet 440044b.pdf download
16F84A datasheet 35007b.pdf download

Source from: http://picprojects.org.uk/projects/ledchaser/index.htm