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View Full Version : "Low Tech" Bar Code Reader -- Possible?



Scope
04-02-2010, 09:14 AM
Hello Microcontroller Loving Friends,

Would it be feasible or possible to create a 'low tech' bar code reader using QTI sensors?

Not much like a 'real' bar code, really, but something similar - on a different scale. For example, if I created a large strip of paper with areas of black & white, and assuming I could control the path of the "scan", couldn't something similar to a bar code reader be created using this technique?

I'm thinking of making a bar code reader robot and locating it inside one of the many plexiglass display cases in the main entrance to our school during National Robotics Week and then offering students clues to a puzzle so they can make a key - a barcode key - to "unlock" the robot and watch it do something - light up LEDs, beep, dance, give them a pass to skip school, whatever.

Thanks,

Scope

Phil Pilgrim (PhiPi)
04-02-2010, 12:08 PM
The TSL1401-DB (http://TSL1401-DB), in conjuction with the MoBo-Stamp-pe (http://www.parallax.com/StoreSearchResults/tabid/768/txtSearch/28300/List/0/SortField/4/ProductID/451/Default.aspx), can read primitive barcodes. Attached is a program and some sample barcodes that the program reads. Although the program calls for an LED strobe unit (in devleopment), it should work with any evenly-illuminated subject.

-Phil

WBA Consulting
04-02-2010, 12:45 PM
Should be do-able. Since a barcode is based upon timing (to determine wide and narrow bands), you may need to have a method of moving the "key" under the QTI sensors at an even rate to establish the bands. If you go with simple white or black strips, it won't be necessary as you would be basically be creating a binary input device. With a true barcode format, you will have wide and narrow black stripes and wide and narrow "blank" spaces. 4 possible options per "bit".

very interesting idea however!

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Andrew Williams
WBA Consulting
WBA-TH1M Sensirion SHT11 Module (http://www.aestheticacoustics.com/sht11_01.htm)
Special Olympics Polar Bear Plunge, Mar 20, 2010 (http://www.kintera.org/faf/donorReg/donorPledge.asp?ievent=322002&lis=1&kntae322002=BDAEE98623FB443591C072E356710D6B&supId=265642883)

erco
04-02-2010, 11:01 PM
With just a phototransistor and IR LED, I made a reliable BS2-based stripe counter circuit, it can detect 3-10 b/w stipes over a 2.5 " length, moving at a decent clip. All stripes were ~.150 wide. With a smaller sensor and longer distance and lower swipe speed, you could count a lot higher.

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"If you build it, they will come."