💬 NRF52 Recessed Vibration+Contact sensor for door/window

[openhardware.io]

https://www.openhardware.io/view/434/NRF52-Recessed-VibrationContact-sensor-for-doorwindow

[scalz]

Work in progress
I'm waiting for pcb and should get them soon as they have been shipped. can't wait to try this new board and compare range with my Aeos custom antenna board
If performing well, then i may ask to a fabhouse for PCBA, as it should be a "cheap" board.

[NeverDie]

Nice work!

[Nca78]

This is getting really small, it's great to get power consumption low enough to be able to use a CR1632 for a long time.

[d00616]

Wow. Looks perfect.

[Terrence]

@openhardware.io So, I have been looking for a way to determine if a door lock was locked. Is this that?

[d00616]

@scalz Is your plan is to drill a hole into the window frame and put this board in?

Most modern windows here in Germany have enough space between the inner and outer windows frame to place a flat board between. My windows have a slot of ~1,8cm and my door of ~1,2cm.

[scalz]

@Terrence it's for detecting intrusion, if the door is opened or not. The accelerometer for detecting vibration, if intrusion is in progress (before door is opened)

@d00616 yes, planning something like that for the drills: (pic from internet)

For my house, or some of my friends, that would work well, some others not. when that's the case, i'll use my aeos board as a common door sensor.
Do you mean you would need a smaller board?

[d00616]

@scalz I mean this: https://shopdelta.eu/wireless-window-opening-detector-ja-82m-jablotron_l2_p6386.html Looks like fitting in doors and windows following European standards.

Most new plastic doors and windows in Germany looking like this. The metal at the right side can surround the window.

Graphical view of another frame: http://www.focuswindows.com/product/eurocell-eurologik-70mm/

BTW. your board is perfect to put it into a little capsule and fixating it with silicone at the glass or at the frame.

[scalz]

@d00616 oki. I didn't know these ones. will think about it.

So far my WIP enclosure for this project is:

[scalz]

@d00616 the sensor you showed me above is 25mm width?? so it's bigger to fit, right?

[d00616]

@scalz said in NRF52 Recessed Vibration+Contact sensor for door/window:

@d00616 the sensor you showed me above is 25mm width?? so it's bigger to fit, right?

The width doesn't matter in that dimension. There is a space for an object with a with of 4cm and a height of 1cm.

[d00616]

@scalz You don't need to change your design for me

This is another concept for windows.
http://www.eq-3.com/products/homematic/heating-and-climate-control/homematic-wireless-window-rotary-handle-sensor.html

[scalz]

Here is a pic of this very tiny door sensor with accelerometer for vibration detection. crazy!

Handsoldered this one! and working well, yay
Need to print a box for this one and install it in a door..

[Fabien]

Can't wait for pcb publishing !

[Fabien]

Why did you use LIS3DH ? ADXL362 seems to be better. You can have 100 mesures / second with 2uA consumption according to this : https://ez.analog.com/docs/DOC-15838

[Nca78]

@Fabien said in NRF52 Recessed Vibration+Contact sensor for door/window:

Why did you use LIS3DH ? ADXL362 seems to be better. You can have 100 mesures / second with 2uA consumption according to this : https://ez.analog.com/docs/DOC-15838

I asked myself the same question, then I checked the prices and if you want it in small quantities from a reputable source, LIS3DH is 1/4 of the price (1.5$ compared to 6$) while keeping a "low enough" power consumption.
ADXL362 is much cheaper on AliExpress but when best price seen on octopart is over 3$ from a non authorized distributor I'm a bit suspicious when seeing prices just over 2$...

[scalz]

i remember of this one
i did this because:

• i have lis3dh in stock and wanted to validate my idea.
• cost. LIS3DH is one of the cheapest and low power accelerometer
• fabhouse usually source at known suppliers in case of pcba, and the adxl is not very cheap.
• I2C because it was really very tight to route the pcb regarding the very small size, and without signals vias on bottom touching gnd coincell (and i'm not fan of tabbed coincell.. ) . SPI would have needed more pins to route
• it is mainly for detecting tilts on door intrusion or knocks. I didn't need a very precise accelerometer for motion.
• I wanted to make a very cheap but reliable door sensor. I think goal is achieved

Too much work actually, plus received some new launchpads to evaluate, i also need to assemble some of my new boards for the faire etc., so, i'm not sure yet when, but i'll take a look whether the adxl would fit, in case you really need it

[korttoma]

@scalz is there any chance that one could buy this device preassembled from you?
I was thinking I could use something really tiny as a one button scene controller and found your design.
Maybe you can even leave out some components in my case to keep the effort and cost down?
Or do you have some other design that would fit my purpose (small one-button scene controller)?

[Nca78]

@korttoma said in NRF52 Recessed Vibration+Contact sensor for door/window:

Or do you have some other design that would fit my purpose (small one-button scene controller)?

Hello Tomas, I have bought one of those. They are over 20mm diameter so not as small as the one from @scalz but still pretty small and they have a physical button + a led (and an unpopulated footprint for an accelerometer, too).
This is the one I bought but there are many seller, I hope with a better price as when I bought it, I paid less than 4€ and shipping included. I have received mine but not tested programming it yet, if you want me to confirm there's no problem to reprogram it I'll can check it during the week.
https://www.aliexpress.com/item/2V-3-3V-NRF51822-Bluetooth-4-0-Wireless-Module-For-iBeacon-Base-Station-Intelligent-Control-System/32824004498.html

[korttoma]

Nice @Nca78 ! With case and everything it is perfect! When you find the time to test it would you mind creating a new thread for it with details like what I would need to be able to program it?

[NeverDie]

@Nca78 said in NRF52 Recessed Vibration+Contact sensor for door/window:

(and an unpopulated footprint for an accelerometer, too).

I wonder whether that unpopulated footprint is where the antenna is?

[Puneit Thukral]

@scalz May I request you to share your code for it please. Thanks.

[skywatch]

What ever happened to this?