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Toilet light wall
LED screen made of empty toilet rolls
The first idea was to reuse empty toilet rolls and make some fun with arduino and some LEDs. After gluing first block (4x3 LEDs connected to Arduino Nano), I've decided that it would be cool to control it right from the android. So I've added one BT adapter and created an android app. As the time went by, another empty toilet roll appeared. So I've built one block after another... After some time I've set my goal to have 4x4 blocks all together (192 LEDs). As the blocks were adding, the functionality of android app was also rising.
first 6 blocks
What it can do ?
Because it is quite straightforward from the video below, let's just briefly list the features from an android app:
toggle random LED (screen saver)
animation (includes also editor for key-frame animation)
simple game using accelerometer
Was there something interesting ?
Aside from the gluing, soldering and programming, I've come across few interesting things:
I needed to create a protocol so the lights will be showing in real-time. I ended up with 2 bytes for each block. 12 bits for the light and the rest 4 bits as an identifier in the grid.
I've never used multiple bluetooth devices before. In this setup, my power resource was not sufficient enough so i needed to split the screen and use multiple bluetooth adapters.
view from the back
To sum it up, I've made quite a large screen (76x60cm) with a horribly small resolution (16x12px) that can be controlled only via bluetooth with a custom protocol. The possible use-case might be as some sort of art exhibition object or as a domestic screen saver.
Why A friend asked me if I could create an android app using his new Yi Dash Car Camera . Camera's parameters look very good and the price was quite low. He showed me a native Android app that was already on Google Play. He needed to download a list of video files and search them by specific time. About camera Camera has its own wifi. So If you want to do something, you need to be connected to its wifi. Camera automatically starts to record a video (each about 3 min long) when it's turned on. During download or changing settings recording is stopped. In the official app, there is also an option to take a picture (this is done via screenshot from the stream). What I did First, I've tried some SDK from the camera's company, but it was not supporting this one. After quick mail to support, I got confirmed that this camera does not have any official SDK. My next move was to download their app and look at the source code. I've used online decompile
Detecting changes in Android contacts Intro In next few lines we will talk about detecting changes in Android contacts. Android Os provides a storage for contacts called Contacts Provider. Contact Provider allows you to manage an access to a structured set of data and standard interface that connects data in one process with code running from another process. Structure Android Contacts structure consists of many tables, here are few of them. ContactsRaw table: (listing important rows) _id - RAW_CONTACT_ID account_name - e.g. email address account_type - account type e.g. com.google.com deleted Table ContactsContract.RawContacts.CONTENT_URI contains original contacts. This table mainly stores raw_id. The contact details are stored in Contact Contract table. Contacts table: (listing important rows) _id - CONTACT_ID (this id refers one group of raw_contact_id ) lookup - link to all contact details and contact in this table Table Contacts.CONTENT_URI consists of
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