Single-use temperature data loggers?

[justanothercanuck]

So work occasionally throws out these temperature data loggers that according to the specs are for single use only...  They use 2 different models, but here's the info on one of them...

http://www.sensitech.com/products/tt4usbfood
http://www.sensitech.com/assets/datasheets/fdtt4usb909.pdf

I got bored and cracked two of them open and noticed that it's just a battery with an ATMEGA, some support circuitry and a zebra strip glass LCD.

If that's all that's in them, I wonder what it would take to hack them to being re-usable, and possibly as a general use thermometer (since the range appears to be -30 to 70c)...  My guess is they're either doing the single-use stuff by code, or battery voltage.

Sorry, no pictures of the boards at the moment, if I remember, I'll crack them open again and take a few.

[Ian.M]

Due to the security requirements of their application, I suspect you'd have to reverse engineer the hardware and reflash them with your own code, as if they could be reset for reuse by any simple method it might be possible to compromise their log and cover up a storage/shipping temperature control failure.

[Yansi]

awwww I have a bunch of those gizmos in my lab too. There's not much to reverse engineer inside. There's a crappy old ARM from Atmel, big 8bit cheapass MCU for handling the display, some ultra-hermeticaly sealed zncl non-rechargable battery and thats mostly it. The temperature is measured by a blobby NTC.
My friend even googled out matching PC firmware for these units, but we hadn't been successful runing it, because it required some license number we weren't able to find or hack around. But I think there is nothing interesting, only if you want some basic parts and two crappy old MCUs. 

Here's a hi-res photo of the similar units I have. (Hope the eevblog will upload it).

//It won't. So only a small preview and here's link for the hi-res: http://n34.imgup.net/IMG_36822527.JPG


Oh, and I forgot to mention, it is not probably soldered with the patented european ROHS solder crap, it seems it is nice lead solder on the board.

[amyk]

Free is free... USB MCU with display and temperature sensor isn't so bad.

[Yansi]

It IS bad actually.  Opening the heck-of-a-solid hermetically sealed glued or welded plastic enclosure plus desoldering the old crusty MCU plus one stupid NTC is simply not worth it.

You can have modern MCU with USB for just about one or two bucks.

[Ian.M]

Who cares how cruddy the CPU is *IF* it can be reflashed in-situ and a free toolchain is available?  It cant be that bad as it does USB mass storage + composes a PDF document on the fly.  Of course having to crack the case is a P.I.T.A. but once the board layout is accurately known, it may be possible to simply cut access with a pilotless hole saw in a mill or pillar drill for reprogramming and just put a plastic bung in the hole afterwards.

[justanothercanuck]

Oh crap, I completely forgot I posted this...  and figures, work threw out the box before I could snap some photos.

Well isn't that funny, the other ones in the box were actually made by Libero.  Not sure if that's the exact model, but it looks close enough.

I also forgot that modern MCU's do code protection...  which kindof sucks, but I guess that's how they make their money.

Eh, what are you gonna do I guess...  maybe I'll start learning how to code with AVR and build my own one of these days. 

Was still interesting to see how basic these things were.

[AleXis6]

anybody found a way to reuse such devices? thank you

[Yansi]

You can reuse those only as a source of components. And the MCU is usable only in case the debug interface was not disabled, so there is still a way in to replace the FW with yo own. I would'n bother with these. Too much effort.  Silicon crisis seems on the way out, MCUs seems cheaper than ever.