(*****) Uhlmann & Zacher CX2172 NFC / BLE smart door handle review

Well bummer: I was about to order a second handle for the storage area just outside the company building. It was a perfect fit for that particular door, only I have to drill a couple holes in it to fit it.

So I asked my boss permission first, and he said: “Weeell, now you see, the problem with that storage area is, we kinda built it without asking the other co-owners of the building their opinion, and they’ve been trying to get us to tear it down for the past 20 years. Now we’re in a sort of truce: they don’t like it but they quit bothering us with it for now. So I don’t really want them to see a new handle on the door, because they might go on the offensive again.”

Damn and blast… Now I have to build some homebrew solution that stays hidden on the other side of the door, when there’s a nice commercial option available :frowning:

Disguise the new handle as an old handle lol

Can’t do that: There is no handle right now - just a key. That’s why I have to drill holes: the lock case can take a handle, but none was fitted originally. Right now we open the door only with the key.

What about a xAC activated thing that manually turns the key/knob on the other side?

Yeah that’s what I’ll do probably. There’s a thumbturn on the inside of the door. I’ll probably make a custom one with a big-ass servo in it. The most important thing is that it shouldn’t look geeky or anything: this is not my home, I need to make a really clean install.

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Question, how do you make the servo turn one way a certain amount and the other a certain amount on alternating activations with just the xAC? Or do you throw an arduino in there as well?

Arduino and shield prolly. Or I find some ready-made actuator with a digital logic control line in our pile of junk.

Ah, at the point that it needs a logic I’ll just use a pn532 at that point

Main reason not to do that would be to avoid remembering master keys and approved keys etc. - those state machines and memory structures, while not necessarily complex, can be a pain. Even a simple ATtiny microcontroller could read the output of the xEM AC v2 and produce the required pwm output for the servo

Well, there will only ever be like 2 or 3 cards ever used with mine so it’s not too bad.
Also i already have some pn532s and they need the arduino so I’d rather save my arduinos for them if possible and use the xAC for something simple like a garage door…

You’re giving them too much credit I think. The Samsung Ezon locks also do this… I can reg smartcard chips but not read them in normal mode… I think this is honestly because the “normal” read routine is probably copy pasted from sample code from the chip supplier and reads IDs in a very shitty way, while the registration stuff needs to be custom programmed and that’s when the coder actually reads the spec sheet of the reader chip and properly pulls the IDs from the iso14443a select process.

I’ve seen some honestly very terrible code samples from reader chip suppliers.

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Yeah I was just guessing. I have no idea what it’s doing exactly, I just know it’s obviously not designed to handle any sort of valid tag, and that it’s not the same code doing the reading in normal mode and enroll mode (which, as you correctly point out, screams sloppy development).

Sample code falls under support, i.e. it doesn’t make money. Bean counters don’t want the developers spending too much time on support.

I’m lucky at my company: I suggested that we spend time developing impeccably-coded open-source APIs for our products, and they were wise enough to agree 100%. Our customers like the level of support and they come back for more, and my company realizes it. It’s nice to work for someone who see further than the next quarter.

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And now I know the battery life: a shade over a year on one CR123 (410 days to be precise).

Changing the battery is easy enough: undo the little hex set screw at the back of the handle, slide the handle cover out, change the battery, the handle reboots and calibrates itself I guess (it makes odd motor noises), and you’re done:

image

This is much less battery life than my BeCode AIR+ that gets about the same usage, has been running for 1 year and 9 months on a smaller single coin cell, yet shows no signs of quitting. I’m guessing the useless BLE transmitter inside the handle accounts for the wasted power.

I doubt the ble radio has much to do with it but honestly battery abuse probably accounts for shorter life of many devices… it’s strange to me how many engineers won’t pay attention to momentary draws that peak over the maximum safe draw on things like lithium cells. Sure the battery can supply the required current but at a lifespan cost to the cell due to chemical breakdown… lost potential chemical energy… every time it happens. Usually this happens with mechanical actuators like those found in locks. That or they put a leaky capacitor there to try to handle the peak start draw of actuators like that and the cap just bleeds power constantly.

In any case it would be difficult for a ble radio sending standard advertising packets out but otherwise going unused to cause much drain on a cell like that.

I’ve recently analyzed BLE traffic in a device I was debugging, and you’d be surprised how much the power draw rises when you have a bunch of cellphones and laptops in the vicinity constantly sending service discovery requests to the device.

BLE is much less low energy than what most people think. It’s only great when there’s zero other BT devices around most of the time.

Here in the case of my door handle, it’s surrounded by cellphones and computers. It gets quieter at night of course, but for 8 to 10 hours a day, it’s being fingered by people’s tracking devices of choice.

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Those phones are doing it wrong then… they only need to do that once and be done… WTF are they doing?

The same thing, over and over

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Fuckin BOO. That’s def not low energy. Fuck man I’m so tired of phone OSes “phoneing it in” (angry pun)

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I’m sure each cycle counts as low energy, they probably just have things set to cycle absurdly often because people are stupid and need instant responses from technology

Or something stupid like that

Well, I mean, the advertising packets should be infrequent and thats controlled by the ble device. When another device like a phone wants to figure out what gap/gatt profiles the ble device has they really only need to do that once… like ever. Those things don’t change… it’s basically a list of ble profiles and services the ble device supports. Why would you ever want to keep hitting it over and over?