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What’s the deal with barcodes?

I was recently asked by a reader to elaborate a bit on barcodes and the bardcode scanner I implemented with the Kitchen PC. So, here’s some info on how we use the kitchen scanner, as well as some other fun information on barcodes

When I first read about the idea of a kitchen scanner I thought it was a bit ridiculous. Overkill. Unnecessary. A little “What would I use that for?” But you know what’s REALLY weird? I mentioned the idea to my wife when I was first designing the computer and her eyes lit up, at which point she all but demanded it be included. Go figure.

First, what is a barcode? A barcode is basically a way to encode information so that a machine can read it quickly and efficiently. An example of this is the UPC, or “Universal Product Code” and is found on just about everything you can buy in North America. A UPC will have numbers at the bottom, and all those black and white bars are the same numbers, but in computer terms. Plus, because of included “error correction”, a UPC barcode can be greatly degraded (“messed up”) and the scanner can still read it.

Here’s an example of a standard UPC and what the different digits mean:

The first digit is the number system, next five digits are the manufacturer code, and the next 5 are the item number. The remaining digit is the checkdigit.

Want more info? Here’s a pretty good article on how UPCs work.

For the geekiest among you, YOU can even figure out how the check digit works to fill in “missing numbers”.

Barcode Scanners
Now I needed a way to read these barcodes. Upon researching barcode scanners I found two things: 1) the good ones are super expensive new, and 2) they read information all different ways. Following are the types I’ve found:

    • Pen readers

      These are the kind you see a lot at the libraries. It’s a thick pen with a sensor on the end and a cord that goes back to the computer. You run the pen along the barcode and a little photodiode reads the reflected light. These tend to be lower priced than other types, so quickly made my list of possibilities. However, wasn’t crazy about having a pen dangling from the PC, and my wife’s #1 requirement was “no computery stuff” laying around.
    • CCD readers

      These are the kind you tend to see in many retail stores. If the associate has to put the tag right up against the device, it’s probably one of these. They reflect ambient light to a bunch of little sensors. Downside is they often need to be almost touching the sensor. Upside, they’re cheaper than the better alternatives.
    • Laser scanners

      These are the creme de la creme…and the price usually reflects it. They shoot a laser line that reads the barcode and frequently include mirrors, such as the big scanners at the grocery store. They can be handheld or stationary and they work from several inches away…after all, it’s a LAAAAASER! Unfortunately, the price break tends to be a little cost prohibitive for your average consumer.

The other thing I had to keep in mind was that I wanted a scanner that simply read the barcode as if I was typing the number in on the keyboard. Many of the scanners I found had two versions: the “keyboard entry” version, and one that read a bunch of other symbols too, which I’m sure makes sense to the software reading it but does me no good. In fact, the CueCat barcode scanner is a pen scanner that can be found on eBay modified to only read the keyboard entry data:



This is actually a favorite among hobbyists because it can be found in the sub-$10 price range…that, and the fact that the encryption used in it is weak enough to break with instructions on the internet. But I digress.

So I wanted a scanner that could be hidden, read a barcode from a few inches away (margin of error = user friendliness), was reliable and didn’t cost more than the computer itself. The obvious choice was a laser scanner and the remaining requirement was met by the handheld version made by Metrologic. Found a used one on eBay and was on my way.

And mounted:

The downside to any barcode inventory system is the initial setup. If we wanted to track inventory, that means I’d have to scan every item in our kitchen and pantry, and then rely on my wife to scan every item she uses. That just seemed absurd for everyone but the most OCD person. Option two was to track a grocery list…much more manageable, and my wife agreed this could actually decrease her workload. grocery list it was. However, we still had to either create a database of everything we buy or find a pre-existing database online to use.

There are several sites out there for this kind of thing, but the easiest to implement I found was It’s literally a website with a single field and an enter button. You scan (or type) your item number, submit it, and it adds it to your list.

Your list can then be printed from the website or you can subscribe to your grocery list via a custom RSS feed to review, perhaps, on your web-enabled cell phone at the store.

This has turned out to be the easiest method by far. Plus, if you scan an item that’s not in the DB, you can add it, and then it’s available to everyone else who uses the site…which means the database is maintained by all the users, making it grow very quickly. Downside? There are a few incorrect item numbers…I haven’t come across any yet, but I’ve heard of a few people having trouble getting the developer to correct them. Nothing’s perfect.

Side perk: you can add all those little frequent shopper barcode numbers to your Grocist account and it will include the individual barcodes for each store on your printed grocery list. When you get to the register, just scan your shopping list and you’re done. Nice!

QR Codes
So far we’ve been talking about 1 dimensional barcodes…the kind you see represented as a UPC on everything you buy. However, no barcode conversation would be complete without talking about the latest fad, QR Codes.

While UPC barcodes are one dimensional, QR codes are a type of two dimensional barcode…which means data is stored left to right AND top to bottom. QR codes are a cool implementation of this in that they create a standard for sharing information…URLs, addresses, or just plain text. Following is an example of my business card as a QR code:

QR Code

Huh? Yeah, that’s our business name and website encoded as a 2D barcode. To read it, you need to install [usually free] barcode scanning software on your phone. Point the phone’s camera at the code and BAM! The information is displayed. In fact, it can be used for phone numbers and SMS to automatically call or text instead of having to type in the number. If you scanned the above barcode, you would get the following information:

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So there’s barcodes in a short(ish) post. Any comments? What are some strange ways you’ve seen barcodes used?

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