Abstract

The microcontroller based Barcode Decoder decodes code 39 .Code 39 was first barcode symbology to encode alphanumeric data strings .It is for this many industrial groups accepted this technology for their labeling requirements .It is widely used as standard for their labeling requirements .It is widely used in variety of applications. Hewlet- Packard's industrial Digital slot Reader is used here.

HP Barcode decoders provide an excellent scanning performance on a wide range of bar-coded cards and badges .When a bar coded card is swiped the slot reader gives a stream of pulses with varying widths .The count corresponding to these pulses widths are stored in the RAM. These are then decoded by the software, which is written in the PL/M -51.PL/M-51 is a high level language for programming various families of microprocessors and microcontroller .The Intel Corporation designed it .later the stored pulse widths are compared with the character set and the decoded output is displayed on the Liquid Crystal Display.