Tiny Android-based TFT wall panel

Hi there. Looking on different HA forums I more and more think about idea of designing my own product, because I can not find suitable device on the market. A kind of start-up.
I’m an experienced electronics developer and know, that it will take time and money to develop it, so it has to be interesting to community in order to start selling it. Otherwise it will not pay back my costs.
So what I want to implement - is a tiny TFT based wall panel. As a prototype you can look on this KNX Thermostat from Berker

The main characteristics of my device are:

  • form factor as standard EU switch or socket, to fit in standard EU wall opening. The device itself most likely will be flat and the size will be same as standard insert for popular switching systems like Jung LS or CD 500 (70x70mm) or Gira 55 (55x55 mm), so that user could install it in standard frame.
  • 2,5-3" fancy capacitive TFT Touchscreen
  • Android OS, so that user could install it’s favourite GUI app - Imperihome, Dashpanel, iViewer, Habdroid etc. Off course you have to consider small screen size, when designing your GUI. But screen should be big enough to fit at least couple of virtual buttons.
  • Connection - WiFi at first place. Then use your Android app to run Rest API or MQTT on top of it.
    In future I might add Ethernet with PoE.
  • Power Supply - microUSB connector on back wall. Use standard USB charger like Apple A1385. In future I might think about adding small battery and some kind of wall dock, so that user could take panel from the wall and use as remote control.
  • No GPS, no Bluetooth, no cameras, no Mike, no speaker(use Alexa or Google Home for this). Just simple Android.
  • maybe Temperature sensor.
  • target price below 100€

As a function I see it as replacement for standard wall switches and Thermostats. Eg.

  • light control, dimming
  • Jalousie Control,
  • Thermostat set-point adjustment
  • all kind of simple one-click functions, scenes activation.
  • It should be easy to integrate in any kind of home automation system
    Just couple of example screens, you could have there (off-course they will be in colour) :

What do you think about such device? Would you buy this thing for your home automation? Is there something to add/remove?
I could create device based on ESP8266, STM32, Arduino and other platforms, which might be cheaper a bit, but Idea behind Android is that in this case user virtually doesn’t need any programming knowledge in order to program such switch.

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Interesting. Being in the US this wouldn’t work in our switch boxes but I have a question about the power supply. If it is replacing (taking the spot of) a wall switch, how will the power be run behind it to connect to the micro USB? Are you able in the box to run power wires, connect them to a USB plug, and have room for this device all within a box?

Sounds like an interesting device! I’ve only thought about this for a few minutes, but here’s a few suggestions:

  1. Include a motion sensor, mainly for automatically un-dimming the backlight when no one is standing in front of the wall panel but in theory could be used also for presence detection or security if the motion sensor had enough range.
  2. Include a light level sensor.
  3. Use a USB-C connector for power rather than micro-B.

Of course, adding more functionality might drive the cost up and I think that keeping the cost to 100€ would be good (even less would be better).

Pretty interesting, although the main point I miss would be the power supply. In my walls, I have only one slot free if I would remove the light switches and replaces them with your vision.

If you would manage to integrate a power supply in this small form factor (which seems to be possible, some companies offer 220V power sockets with an additional USB slot (e.g. Wall Plugs on Google)

Also, in Europe we tend to have brick walls with defined size / depth so the depth of the unit would be a critical factor.

You’d need a custom face plate, but it would fit in a US dual-gang electrical box.

Thank you all for positive feedback.
Concerning power supply option: I know it’s pain topic by experience.
First you have to understand - putting HV power supply inside device is a complex thing not only from design (creepage distances, insulation, etc), but also from safety/certification point of view. I don’t want to be responsible if device kills someone. And certification costs are quite huge.
Therefore low voltage power supply option is preferable as this becomes problem of power supply, not my device.
USB seems to be industry standard right now. So basically my solution is simple - if you have 115/230V in our wall, you just use tiny USB charger, which fits in wall. The one from iPhone above is really small and I know even smaller, so there should be no problems with this.
The panel itself is going to be flat - 5-7mm, so it will not occupy any space in the wall opening.

Being in the US this wouldn’t work in our switch boxes

Offcourse US or UK versions are possible, if there are demand.

I don’t feel it as good option. Dimming/undimming can be done by time or touching. Usually the TFT will just stay on. All these motion and light sensors require some place on front panel, which I don’t see now. Also it has to be supported by Android OS, but I don’t want to much specialized firmware.

Anyway it’s going to be smallest standard USB connector, so that anyone has a cable for it.

Yes. Otherwise cheap Android Tablet or Smartphone becomes more preferable.

I would prefer this option. I know I’m not the only dinosaur preferring wired to wireless … but it also would allow centralized power supply (the PoE hub) and no mains in its wall box at all.

No speaker, understood, but a beeper can be really useful in a UI for feedback to user.

Sorry to crash the party, but I wouldn’t buy it. You can as well put a simple (used?) smartphone on the wall.
Or a Pi with a TFT extension. The stuff is there already, it’s just a slightly different form factor.
People either already use it that way, or they don’t deploy it for reasons beyond the functionality you mentioned, such as lack of software integration into their HA system, lack of useful UI, or design.

The form factor makes all the difference - I haven’t seen a smartphone or Pi installation that sits perfectly flush with the wall and looks seamless, rather than a screen stuck onto a wall.

I would definitely buy something like this.

I’ve got HabPanel running on a 4" screen and it’s usable, but not wall mounted yet. I think a 3" screen would be the smallest you could go to from a user experience point of view.

I think this would be a niche market within an already niche market. There seems to be two schools of thought in HA. One wants to go all tech, remove everything physical and be the home of the future. Others (me included) see HA as a layer of technology, one that enhances but not replaces.

When I look to implement, my goal is so that anyone (friends, relatives) can come to my house and not be confused how to turn a light on. No special control panels or having to pull out a phone. Physical switches are there, just zwave, and the HA is built upon that.

Markus, that’s exactly what stays behind this product idea:

  • Simple smartphone will cost you at least 100€ - I had in hands those Huawei terminals, and they are awful. Plus smartphone on the wall doesn’t always looks nice - the only good ones are Sony’s, but they again much more expensive, than 100€
  • Pi with TFT extension - first, not good form-factor. Second it’s Linux, so not really suitable as GUI for non-programmer. Third - some assembly required.
  • Yes, lacks of integration, lack of useful GUIs. Arduino and Co or ESP8266 will not provide you nice GUIs, unless you are a good programmer. And Android does - there are many apps for any HA Integration, from with I really like CF iViewer with powerful (my) MQTT client, that can be connected to any Opensource HA. So I will provide reference designs which would allow creations of customized GUIs without programming
  • I’m going to add some “nice-to-have” home-automation-specific features, like Temperature sensor or PoE, which usually absent in smartphones, but will give you capability to some hardware, reducing installation costs.
  • And finally WAF - that drives the market.

Finally I see a niche in niche market of DIY HA Installations, where users know how integration should work, but don’t want to design peripheral hardware themselves. Raspberries and Co occupied their position as Home Automation Servers. Z-wave seems to solve sensor Issues. But other than big tablets or Smartphones no-one solves intelligent switch issue.

The main problem with using a Raspberry Pi plus a small touchscreen is the software. Linux + X Windows + a browser does not make for a good experience IMHO, and you waste a lot of memory and CPU. It would certainly be possible to write a Raspberry Pi UI that doesn’t use X Windows, but as far as I know no one has done so. It’s possible to run Android on a Raspberry Pi but from what I’ve read so far it’s not quite ready for prime time…

I would be interested in such a device, although in an existing installation/retrofit I would only be able to deploy a limited number of panels. In a new setup would probably opt to install in addition to physical switches

The eastetics of the frame/front panel are quite important and unfortunate something where most devices fail.

Important factor for me would be the ability to integrate with my switches, sockets etc. (I use Gira frames, but similar systems like Busch-Jaeger, Jung, Peha, Berker etc exist). Ideally you would only fabricate the internal device and combine it with the Original frame and Faceplate from Gira etc. Only this way you can guarantee seamless integration as otherwise you will find difficulties to match the various colors/textures/finishes (just think about different colors of white…)

Smart move to opt for having only 5v power as this takes away many regulatory/certification and liability issues.
Would recommend to look into future option to offer external power supply module that would go in the back of the wall box (maybe fixed by screw to the back of the display module?). Different module could be offered for 220v input or PoE input or something else. This modular approach will help you keep the number of variants of the panel down (higher volume on single sku, more cost effective)

Yes, you reading my thoughts. I think about the same combination - using standard Gira/Jung Frames and custom internals. The only problem I see, is that some series have quite wide frame and smaller inner window, which reduces size of display to something useless.
For example quite popular Jung CD 500 or LS Series have a big inner window of 68x68mm. There I can easily fit 2,8" or even 3" display.
But Gira 55 - another popular series, has only 55x55mm window, for which I have to use much smaller display.
Therefore I can not guarantee, that device will fit all possible frames.

Hi, this does sound like an interesting idea. You mentioned the ESP8266 as a possible hardware layer, if that’s what you opt for it would be worth adding support for i2c sensors rather than building sensors into the unit as it allows for customisation and future sensors.
Would be interested depending on the aesthetics, I think the idea of being able to pop it out and make it portable is a nice option. However I don’t see it replacing a physical light switch for example, a tactile, single function switch that is familiar to everyone has a lot going for it.

It is always rather hard to start small production, and maintain some kind of profit from it (of at least not go minus). Remember, if you sell is, you will need CE approval, and since your device contains radio(s), it will not be the lowest cost at the test house. Also, you will need to cover warranty etc. etc.
Sorry if I’m sounding too negative - I don’t want to be a a*hole. :slight_smile: Just saying.
If you would add 230V power supply, and motion sensor to it, I think you would have a larger audience. I would certainly buy it then.

(From another electronics developer)

The device will not feature ESP8266, instead there will be some Android capable processor, like Allwinner, for example. I will check I2C capability, but it worth mentioning, that Android has quite limited support for such things, as mentioned in http://static.googleusercontent.com/media/source.android.com/en//compatibility/android-cdd.pdf. The only ones useful for HA there are ambient temperature sensor and photometer (light sensor). Maybe proximity sensor could be used as motion detection also.

I can do some trick and you will :heart: tactile feeling from this device. Pressing on the screen will feel like pressing real button, and if you will make sensitive area big enough in your GUI, you would be able to operate it almost blindly. So I hope it will replace physical switch at some point.

I’m aware of those things.:slight_smile:

I’ll be honest I’ve not read all the replies whilst I love the idea I see two problems…

  1. Don’t force people on to an OS - sure make Andriod an option but how about letting me put Linux on it if I want to? I don’t like the idea of play store and all the extra Andriod rubbish for something I’d want to be super simple…

  2. Power is the key issue in my opinion - I take your point about safety but if you want to be a game changer that is where it is… I have lots of 220v wires in my walls - I don’t have any 12v… I don’t want a socket inside the wall to plug a USB charger into… I am sure there are some mains wired USB transformers out there but as someoen that isn’t electircal I don’t know how good/safe/efficient they are…

but in my opinion power is the problem for wall mounts. I take your point about safety and that you can squeeze a USB charger in the wall but that just creates issues.

I agree with this on some levels - and having the switch for when the server crashse and you can’t get it running again is important…

That being said I don’t think ZWave is there (in the UK) for a retrofit option yet and the other, Lightwave, is only receive so no transmit when used locally which makes for an imperfect system.

On the flip side - I feel Philips Hue have missed a trick not having a lightswitch replacement which just passes the 220v through to the light and then has a software based switch being powered by that (essentially combining the battery based options they have) with something that can make it so my Hue bulbs always have power…

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