Tiny Code Reader: a $7 QR code sensor
That's inexpensive enough to be the basis for a modern recreation of the CueCat:
Sadly, Useful Sensors seems to have pivoted to other edge AI tech and no longer sells this or their person detector.
Somewhat incidentally, is there an actual description of how a low-tech QR code reader would work? I’ve looked for this a few years ago and all solutions I could find were of two flavours: (1) use ZXing (“Zebra Crossing”, a now-unmaintained library[1] for every 1D and 2D barcode under the sun); (2) use OpenCV. Nowhere could I find any discussion of how one would actually deal with the image-processing part by hand. And yet QR codes are 1994 tech, so they should hardly require fancy computer-vision stuff to process.
Can also do this with an esp-32 camera module which are cheap and all-in-one https://github.com/alvarowolfx/ESP32QRCodeReader
My experience with small QR code readers like this on ESP32 boards is that without a viewfinder, they lose a lot of utility. The feedback loop that a viewfinder gives with positioning and knowing when the QR code is detected is invaluable.
If you pair this with a eink display you could send messages back and forth with another device https://remotehack.space/QR-TX/
A fridge-mounted ESP32 barcode integration would be pretty awesome for tracking fridge inventory
I've had a recurring idea in my head of a sensor you could mount in your car, and then be able to read QR codes from the side of the road, and get an index of all the businesses you'd be driving by for later lookup. Not sure how feasible or useful it'd actually be...
I love these. Kinda insane they got it packaged so cheaply.
Anyone who knows of a cheap sensor that works in Linux and can read Digikey bag barcodes?
A cheap android phone would perform better and for much cheaper.
positioning limit may be a focus issue.
typically on these cameras the lens is mounted and focused by a screw thread. there is not usually an 'infinity stop' because the mount is very simple, so i would expect the lens may be mechanically positioned outside the useful focus range. a 110 degree FoV is a very wide lens, so the useful screw range may be quite mechanically narrow, but when positioned properly it will have a very deep in-focus field, capturing near objects and far objects clearly.
the datasheet doesn't say much about focus, but it looks like the rim of the lens is knurled for grip, so try rotating the lens. 'screw out' will bring focus nearer, 'screw in' will push focus farther. i would suggest indexing your start position with a paint pen for easy return, and then index the correct position if you find it.
if all else fails, you could place a small aperture in front of the lens. this will reduce light transmission but also improve the focus field, like squinting your eyes.