In 2007/2008 I built a InfoPanel for my apartment to show me news, the weather and other interesting and fun things. The original InfoPanel was built using a VIA x86 micro ITX board and a 17" touchscreen all fitted in a self made wooden case. The InfoPanel survived until 2012 when I moved to the U.S. It was too old and too big to bring so I dismantled it.
I always missed it and thought about brining it back. For a brief time I used an old Samsung Galaxy Tab 10" but the device was just not right. Starting with a proprietary Samsung USB connecter that didn't allow for nice looking cabling, the device was black and silver so it didn't look too nice on the wall and finally the device was just old and slow. Long story short it only stayed on the wall for a couple of weeks and I just ran a full screened web browser.
The new InfoPanel
Hardware: Android 10" tablet in a white case with a USB connector on the long side.
Software: custom Android app that hides the Android navigation elements and status bar.
I chose a Yellyouth Android 10" tablet, those tablets are damn cheap (just under $100) but also kinda tricky. The good parts: 4GB ram and a fast processor. The tricky parts: The product description says the resolution is 2560x1600 my device reports that resolution in the system infos but the screen reports 1216x800 pixels. The device does not contain any sensors such as a light or proximity sensor (you will see why that matters later). The GSM modem does not support T-Mobile/AT&T SIM cards, I thought this was a joke but I tried a Google Fi data-only SIM (T-mobile) and the device couldn't connect to any network (this is fine since I only use WiFi).
I wrote a small Android application that basically shows a full screen webview. I've added a back and reload button to allow returning to the main page from links I clicked. The application hides all system UI (navigation and status bar). The user can swipe from bottom to top or top to bottom to reveal the back and reload buttons. The buttons auto hide after a short timeout. A really basic Android app!Result
I wanted to conserve power and turn of the screen when I'm not using the InfoPanel. Luckily saving power is a default function of Android (you can just set the inactivity timeout after which the screen will be dimmed and eventually turned off).
The catch: how do I turn the screen back on (without pressing the power button - since that is not super practical!)?
- Motion detection using the camera: several projects exist and I've got it integrated but was not able to get it working while the screen was off (I also didn't want so spent a lot of time on this part)
- Motion detection using the light sensor: I implemented this using a Nexus 7 tablet, a background service monitors the sensor and wakes up the device once it detects a significant change in brightness - sadly the Yellyouth device does not have a light sensor.
- Audio activation: the idea is to monitor the ambient noise and wake up the tablet when there is a loud noise (finger snap or clap), I implemented this using a background task that records audio and discards the content and only monitors the amplitude (there is a built-in method in the SDK to query the amplitude!)
All in all a fun weekend/evening project of a few hours.