Henk: When you say serial output, do you mean it has an RS232 connector? Or is it a pair of wires?

The question is whether the barcode reader is a self-contained unit that actually reads the barcode and translates it to its ASCII representation. This is usually not the case unless the hardware you have is something you connect to a PC.

Otherwise, the output of a barcode reader is usually a high level as it passes over a bar (dark area) and a low as it passes over a space (white area). However, if you stall over a black area for some amount of time, the device will usually go back to a low state even if you are still over a dark area. The sequence of highs/lows can be decoded by the 8052 by determining how long the signal is high followed by how long it is low, etc. A recent project of mine was exactly that.

Craig Steiner