Barcode

"I think Erik is trying to be funny?"

Not really: several contributors have told you that this is not a trivial exercise, and yet you continue to ask to be given free, complete code!

"very sarcy and not helpful!"

Your request looked more like a demand for a freebie than for "help".

"I think polling might not work well, and I think I must use an interrupt."

Now you're getting somewhere!

Whether polling is workable depends on what else your processor has to do - since a barcode swipe is only relatively brief, it might be possible to stop everything else and poll the input during a swipe...

"But should it be edge or level?"

Probably edge: what you want is to detect the start of a bar - which would be an edge.
You then need to time the width of the bar.

As already mentioned, this just gives you the raw bar timings - you then have to process that to allow for irregular and skewed scanning, poor-quality printing, etc, then decode that, etc, etc,...

Barcode scanners are relatively cheap on ebay - do you really need to do this from scratch for yourself?

Have you tried looking on the Agilent site, or others?

"I think Erik is trying to be funny?"

Not really: several contributors have told you that this is not a trivial exercise, and yet you continue to ask to be given free, complete code!

"very sarcy and not helpful!"

Your request looked more like a demand for a freebie than for "help".

"I think polling might not work well, and I think I must use an interrupt."

Now you're getting somewhere!

Whether polling is workable depends on what else your processor has to do - since a barcode swipe is only relatively brief, it might be possible to stop everything else and poll the input during a swipe...

"But should it be edge or level?"

Probably edge: what you want is to detect the start of a bar - which would be an edge.
You then need to time the width of the bar.

As already mentioned, this just gives you the raw bar timings - you then have to process that to allow for irregular and skewed scanning, poor-quality printing, etc, then decode that, etc, etc,...

Barcode scanners are relatively cheap on ebay - do you really need to do this from scratch for yourself?

Have you tried looking on the Agilent site, or others?