TABLE OF CONTENTS How then do we get black and white bars on paper into a PIC? We'll use the simplest possible scanner, a bar code wand reader. To read you swipe the wand across the bar code. There's a lot of black magic that goes into a wand, so I'll assume you will use an already build commercial wand. I recently purchased two unused Hewlett Packard A000-series wands for $5.00 each from an electronics surplus house and similar wands from HP and other manufacturers are widely available in the surplus market.
My HP wand is shown in Figure 25-4. It came with a three-foot cable terminated with a 6-pin DIN plug. (The mating panel jack is a Mouser Electronics part no. 16PJ224.) Although I was able to find HP's data sheet [25-4] for the A000-series wands, my DIN plug had six pins, not five as the data sheet shows. Since you may have a similar problem, I'll go though how I identified the correct pin connection.
Many wands of this era used HP's specialized LED sensor and support chip, HBCC-0500 and followed HP's recommended circuit design shown in the associated data sheet. [25-3] The wand has three connections; +5V (red), ground (black) and an open collector output (white). A fourth connection is the shield for the cable, which is normally connected to the DIN plug's shell. The wiring color code comes from HP's data sheet. Using...
