Brady temperature sensor NFC labels



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Patience my friend.




Ah hell, guess I’m gonna wait a bit longer… but, 2021 starts on 01.01. - so, we eagerly await news on that exact date! :smile:


I’ll get my post and DMs ready at 11:59:59 so we can badger him on the exact start of the day!


Well I’m very disappointed.

Okay then, since you ain’t saying nothing, shall we have a game of “guess what Amal is coming up with”?

I’ll start. Let’s see… It’s an implant with a small C4 charge and a bridgewire. Scan it with the right credentials and you’re a goner. It’ll be called the flexDignitas.

Am I close?

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You’re disappointed? Not as much as I am… you missed a golden gif opportunity here…

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No comment.

I didn’t even see the opportunity :slight_smile: It never occurs to me to post an animated gif in response to something. Maybe I should get some training on that…

If you want training, I’m happy to summon @Pilgrimsmaster for you


Ah no, you got that wrong: PM’s specialty is replacing words with emojis :slight_smile:

He can do two things!


I feel like my brains natural language is gifs, and I have to translate to written text when gifs are not accepted


And… they sent me the oversized UHF tags :frowning:


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This is getting embarrassing… I just received a package with a letter saying “So sorry we sent you the wrong labels, here are the right ones” and a bag full of the same UHF labels :slight_smile:

The package also contains a pamphlet with the motto “Specialists in identification”. Indeed, I can tell… :slight_smile:


Yeah, I got me a bunch of NFC labels today! (shall we say the Brady bunch? … Sorry…)

Preliminary tests aren’t good:

  • I stuck one in the temperature chamber, stabilized at 22C: the temperature it reports swings from 21.4C to 23.3C from one read to the next. While that’s probably okay to track the temperature of frozen goods (possibly it’s optimized for freezing temperatures too), the precision is far too low for body temperature. Accuracy seems reasonable though.

    At any rate, it gives me a renewed respect for the humble Destron Fearing Bio Thermo aka xBT, which performs much better precision-wise.

  • There’s a counter in the URL: each time the chip is read, the counter increases. The question that immediately springs to any programmer’s mind is: how deep is the counter and what happens when it overflows?

    Or said another way, if the counter is 16 bits and I read it 65536 times, does it roll over and keep going, does the chip crash or does the chip disable itself?

    The side question is, since it probably writes the counter to the same memory cell over and over, what happens when said cell becomes unwritable? I will of course test this by reading the shit ouf ot it until it dies (if it dies), but it does not inspire confidence.

  • This being a shitty world of IoT cloudiness where the companies don’t want you to have control over your own devices, sure enough the temperature data is obfuscated. It’s not encrypted exactly - at least it doesn’t appear to be - but it’s not in clear text. Some reverse-engineering is in order.

    I kinda hoped it wouldn’t be, but… no real surprise there: why make it an honest-to-goodness device when you can make it shifty, tie it to an online service and hamper the user’s ability to do what they want?

    Also, the device seems to tack on an OTP, and if you mess with it, the Brady website throws a fit and “disables” the device - meaning it refuses to report the temperature from that point on. Not that I care, I don’t intend to send them any data, but I thought I’d mention it because it’s really sad.

Okay, owned. Sometimes I amaze even myself :slight_smile:


Re precision, it may not be as bad as I thought: the tag’s mass is so small that it has a stupidly small thermal inertia. As a result, I’m picking up a lot of stray heat variations, mainly from the ACR122U reader I use, and from drafts in my office. Just putting it on the reader is enough to make the temperature reading jump 60 degrees in one second. Amazing!

Anyway, I need to affix it to something metallic with enough mass, and read it with an external antenna to assess the precision properly. That’s for another day.



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Tolerance is ±0.9C and standard deviation is 0.3C in ultra-stable temperature environment at 30C over 600 samples. Not great…

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If it’s anything like the NTAG216 then it would be a 24 bit counter. My hunch is that the chip inside it is actually the SmartSensor chip from NXP which has a shitty thermal sensor built in… but I could be wrong. Does TagInfo identify it as an NXP chip?

As for counter rollover, in the NTAG216 this is what the SDS says;

Once the NFC counter has reached the maximum value of FF FF FF hex, the NFC counter value will not change any more.

Therman inertia… I’ve not heard of that term before but it makes perfect sense. NEW PHRASE UNLOCKED!


I am still bitter about that thing. POS

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If it goes over 65535, I’ll get it up to above whatever is needed to wear out the flash and see what happens then.

It says:

  • IC manufacturer: NXP Semiconductors
  • IC type: NHS
  • Capacitance: 50 pF
  • Storage size: 888 bytes

If that’s what’s in them tags I got here, I can see why. Sensor performances are sub-par. Even for their intended application (cold chain tracking), I’m pretty sure a fussy QA inspector would not validate the solution, on account of the fact that you might read -4C when the goods are really at -3C.

Or did you have other complaints?

The NHS3100 is a temperature sense IC that NXP specifically advertises as field programmable, but when you spend countless hours doing R&D only to find out that their execution of that is a hack job side project by one of their engineers that is poorly optimized for non-ideal coil shapes, they tell you to punch sand.