Not long time ago we featured simple Arduino wav player that played music stored in internal microcontroller RAM. Due to memory limitation, you can play only couple of seconds of sound on Arduino UNO. To remove this limitation Kathy Yang extended player by adding SD card, where any size and length music files can be loaded.
Before you can listen for music, wav files need to be converted in to appropriate format so Ardiuno could play them correctly. This is done by special software provided by author. In order to select file and play it, you need to connect to Arduino via serial port debugger, where list of files are visible and with several control commands you can play file, stop, pause or switch to next file. Having this you shouldn’t have problem implementing you own user interface to control player. But more practical way of using it would be embedding sound effects in to project – think of educational child toy or other.
When project goes wireless prototyping with breadboard can be really messy. This is OK with single module, but what if you need several options? This is why TechBitar designed BridgeDuino board that can work as Arduino shield or HUB that can carry several popular wireless adapters including IR transmitter LED, IR receiver, RF433MHz reseiver and transmitter, Bluetooth HC-06 and HC-05, and Nrf24L01+.
Board can sit on top of Arduino Uno as shield or be as base for Arduino Pro Mini along with FTDI programmed adapter. All those adapters already have Arduino libraries available, so there is no problem to interfacing them you just need to be sure when selecting proper control and data pins. BridgeDuino also has several additional features that make life easier. For instance LM1117 3.3V supply for powering Nrf24L01+ module, battery power option with Schotky diode protection, jumpers for programming and configuring other adapters, several I2C and ADC headers.
Sometimes in more complex projects it is a waste to dedicate a line for every LED or button. If you thinking of selecting bigger microcontroller because you need additional pin to drive LED, think of smart way out. Francois AUGER & Philippe Fretaud have shared their technique of interfacing three LEDs and three buttons with three I/O pins.
They used special Charlieplexing method of connecting all together and then wrote code piece to drive LEDs and read buttons. Three additional diodes allow reading buttons without affecting other components. Using three additional diodes is way more efficient than expanding number of pins. See video bellow of live action. Continue reading
Lots of water is wasted in toilets around the world. Standard toilets flush about 6500ml of water mo matter if you are doing light or serious business. Some toilet flushers have dual button where one allows partial flushing, but it is not used in most cases -especially by kids. So TV Miller decided to automate water saving process here. He adopted Arduino system which fills only half of tank with water. This is more than enough to flush human urine. This is most often used option. If someone wants to do serious business, there is a button that once pressed fills tank full while you’re here.
Toilet has several improvements including electronic flush release mechanism based on servo. If this is not enough there is a bluetooth channel which allows flushing toilet with your smart phone. But probably most welcome feature of it is that it helps saving water – about 2 gallons per day. What if 1825 people would install this setup – they would save 1000000 gallons per year.