4 ms·
Wifi sensing is interesting, but you can combine a $3 ESP chip with one of these for a much easier project at lower cost: https://www.dfrobot.com/product-2795.h
by t0mas88 2y ago
Wifi sensing is interesting, but you can combine a $3 ESP chip with one of these for a much easier project at lower cost: https://www.dfrobot.com/product-2795.html https://www.dfrobot.com/product-2795.html
I use those for presence detection in my house. 3D print a small case and for < $20 you have highly accurate presence detection that also works when sitting still. Ideal for automatic light and climate control.
- stavros 2y agoMy problem with similar sensors is that they don't work very well if you're sitting still around 3m away. Maybe my sensor isn't great, but when I'm sitting still at the computer, it frequently thinks I'm not there any more, which ruins any benefit.
- squarefoot 2y agoPairing them with PIR detection should help to also detect stationary warm objects.
- stavros 2y agoI did pair them, unfortunately PIR sensors are even worse at detecting stationary objects (less sensitive to body micromovements).
- Avamander 2y agoIt's difficult to find good PIR sensors though. The commonly found cheap modules don't include a thermistor to compensate for room temperature. Finding one with analog output or continuous detection is even more difficult, most detect changes.
- Avamander 2y agoThere are some that detect heartbeat, I guess those might work. But those are mmWave, not just cheap 2.4GHz radars or PIR.
- stavros 2y agoI've got LD2410B, which are mmWave, so they should detect heartbeat (and do), but not from more than 2-3m away.
- transpute 2y agoIs the LD2410B sensing range limited by the PCB antenna?
- stavros 2y agoI'm not sure, it always just made sense to me that the farther away someone is, the harder it'll be to detect their small movements.
- transpute 2y agoSmallness detection depends on RF: higher frequency = shorter wavelength = more resolution for imaging. Detection range without obstacles depends on transmit power and signal reception. There are other models in the same family which might have more power/range.
- victorbjorklund 2y agoA hack is to put a sensor on the chair
- stavros 2y agoHmmmmm that's not a bad idea, I'll have to see how to do that, though. I don't want cables restricting me.
- swsieber 2y agoIf your fine with zigbee, I could see having one of these aqara door sensors in the cushion of the seat, triggering to closed when you sit on it: https://cloudfree.shop/product/aqara-door-and-window-sensors/ https://cloudfree.shop/product/aqara-door-and-window-sensors... Seems like it'd be finicky though.
- stavros 2y agoZigbee is great, but my chair has a mesh :/ I'll see if I can print something below, so that the sensor is activated, but yes, it does seem that it would be pretty finicky...
- transpute 2y agoCeiling sensor is another option.
- stavros 2y agoFor now I've put a mmWave sensor under my desk, which works fairly OK. It's not perfect, but definitely good enough.
- rpgwaiter 2y agoYou can buy the sensors they use in car seats for like $10 https://a.co/d/0dibAFxc https://a.co/d/0dibAFxc
- 2y ago