EEVblog #637 - Omni Directional Laser Barcode Scanner Teardown

[EEVblog]

What's inside one of those omni-directional laser barcode scanner you use at the supermarket, and how does it work?
Motorola / Symbol LS9208

Datasheets:
Reflective Interrupter http://www.osram-os.com/Graphics/XPic0/00083379_0.pdf/SFH%209202,%20Lead%20%28Pb%29%20Free%20Product%20-%20RoHS%20Compliant.pdf
http://www.motorolasolutions.com/web/Business/Products/Bar%20Code%20Scanners/General%20Purpose%20Scanners/LS9208/_Documents/Static%20Files/LS9208.pdf
http://www.keil.com/dd/docs/datashts/atmel/at91fr4042.pdf
http://www1.futureelectronics.com/doc/RENESAS%20ELECTRONICS/DF2215RTE24V.pdf

[FrankBuss]

I don't know if it is a good idea that these devices can be configured with barcodes, because there could be a joker at the supermarket checkout who shows some of these special barcodes to the scanner and then the interface doesn't work anymore.

[daqq]

Hi, thanks for the teardown.

But I'm pretty sure that this is just a 1D scanner - it would not support any 2D codes (QR etc). There is most likely just a photodiode inside the whole shielding assembly. According to the datasheet it supports the following:

UPC/EAN/JAN, UPC/EAN w/ Supplementals, UCC/EAN128, Code 128, ISBT 128, Code 39, Trioptic Code 39, Interleaved 2 of 5, Discrete 2 of 5, Code 93, Code 11, Codabar,  MSI, RSS variants

None of which are 2D. As such the processing is simpler by orders of magnitude - just process a single 1D analog signal, look for a pattern.

[bktemp]

It seems to work like a flying spot scanner. The sensor seems to be a simple photodiode. The 1D signal is generated by sweeping the laser across the code. This is why it did not work with the laser blocked. This also eliminates any ambient light by simply high pass filtering the sensor ouput.

Could you probe the output of the sensor? It could be interesting to look at the waveform while scanning different objects.

[EEVblog]

But I'm pretty sure that this is just a 1D scanner - it would not support any 2D codes (QR etc). There is most likely just a photodiode inside the whole shielding assembly.

Ah, yes, you are right. I was looking at the new DS9208 Motorola datasheet which is 2D, not the older LS9208. So I had it in my mind it was 2D and was trying to explain it as such. Doh.

[sunnyhighway]

I don't know if it is a good idea that these devices can be configured with barcodes, because there could be a joker at the supermarket checkout who shows some of these special barcodes to the scanner and then the interface doesn't work anymore.

That's why you need to put it into single line scan mode (programming mode) first, by pressing the only button it has.
Furthermore, this button can easily be disabled by pulling the connector.

[German_EE]

Sorry Dave, I just get a message saying 'This video is private'.

[electromatt]

Sorry Dave, I just get a message saying 'This video is private'.

Same here - Perhaps Dave is in the process of uploading a new version?

[VK5RC]

For 2001 Space Oddessy fans , HAL has taken over youtube !
"Dave you know I can't comply to that request" or something close to that anyway!
HiHi

[EEVblog]

Same here - Perhaps Dave is in the process of uploading a new version?

Yep, corrected version, with an additional observation.

[electronics man]

It's telling me it's private as well

[josem]

I don't know if it is a good idea that these devices can be configured with barcodes, because there could be a joker at the supermarket checkout who shows some of these special barcodes to the scanner and then the interface doesn't work anymore.

These devices almost always offer the option of turning off configuration barcodes or only accepting them immediately after boot up.

Any decent supermarket system would have one of those options enabled... but perhaps many do not. 

[Fennec]

It's telling me it's private as well

Working now

[ElektronikLabor]

Yep, corrected version, with an additional observation.

What is different in the current version?
I watched only the old version, which was 1:30 longer!

[EEVblog]

Yep, corrected version, with an additional observation.

Waht is different in the current version?

I added a part on what that mysterious 6 pin slit package might be doing.

[andtfoot]

A while back I had a casual job for a couple of months repairing barcode scanners. It was pretty much only board level swaps for the larger units, and entire unit swaps for the cheaper handhelds.

One of my favourite fault descriptions that came through was "laser no wobble". (well it seemed funny at the time...  )

[Jorpy]

There never was a 53rd  week of 2005.. How can that Atmel chip have been manufactured there?   

[ElektronikLabor]

I added a part on what that mysterious 6 pin slit package might be doing.

Thanks Dave, I also asked myself what it is.

BTW: You also added the curious reflective square on the top of the prism
http://youtu.be/PIn00-qW5WI?t=22m16s

Could it be a counterweight for the balance of the prism? I mean the "something in the corner" thing.

[Cr0oK]

Hi Dave
the mysterious part is something called reflective interrupter. Like this
http://www.osram-os.com/Graphics/XPic0/00083379_0.pdf/SFH%209202,%20Lead%20(Pb)%20Free%20Product%20-%20RoHS%20Compliant.pdf

Greetings Chris

[Refrigerator]

There never was a 53rd  week of 2005.. How can that Atmel chip have been manufactured there?   

Time paradox ?

[SeanB]

Dave, do you want the hand held version of that scanner?

[tinytim]

and no comment wouldbe complete without a link to the defcon vid



and no i have not tried it with tesco special money off coupons.   

[lpickup]

There never was a 53rd  week of 2005.. How can that Atmel chip have been manufactured there?   

What, you guys have never completed a project on December 37th?

[Lukas]

Have you probed the laser diode? I'm curious to know whether it's modulated, which would make detection a lot easier.

[bitwelder]

I think that the shock mount system serves not only to avoid receiving shocks from outside, but also to avoid propagate the mirror vibrations to the external enclosure (which would make the device quite unpleasant to keep on the counter).