DIY Bluetooth Home Automation

blueboard

Interested in a bit of home automation? Don’t know where to start? We just found a great Instructable on making your own bluetooth controlled relay module!

[Kyle’s] been working on this for a while, and finally at his 5th iteration he’s ready to share it with the public. It’s a project you can make from scratch, and each unit will cost approximately ~$25 in components — which can control up to two outputs. He’s included an inkscape PCB layout which you can easily etch on your own using the toner transfer method. The heart of the build is an Atmega328, which helps keep the costs down — after all, it is only controlling two outputs! Then it’s just a matter of adding the components, a bit of soldering, and uploading the firmware! 

The entire design is open source, and [Kyle] would love some feedback to continue improving upon it. The write-up is quite thorough, so if you’re interested, take a look and leave him a comment!

Furbies Sing Queen at Fresher’s Faire

kent-furby

The University of Kent has their own hacker space, called  [Maker Society]. Every year the school holds an orientation for new students called the Fresher’s Faire. The [Maker Society] display at this year’s Fresher’s Faire included a group of partially clothed Furbies singing the classic Bohemian Rhapsody by Queen. This isn’t our first run in with Bohemian Rhapsody and hacked hardware.

The [Maker Society] started by doing some internet research and reverse engineering a first generation Furby.  The Furby itself is a marvel of cost reduction. All the doll’s functions run from a single motor and a cam system. A limit switch tells the on-board microcontroller when the cam is at the zero position. An optical encoder keeps track of the cam as it moves. The [Society] replaced Furby’s internal microcontroller with an Atmel ATMega328. This allowed them to use the Arduino programming environment.

Many classic Animatronic systems use an audio recording for motion. Typically a stereo recorder would perform double duty. The first track would contain the audio for the animation. A second track would contain audio tones corresponding to movement of each of the degrees of freedom of the doll being animated. Because the two tracks were on the same strip of magnetic tape, the audio and movement would always be in sync. Multitrack tape record and playback systems added even more flexibility to this type of system.

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A simple Forth development board

forth

Forth is a very interesting programming language. It’s very flexible and is extremely efficient on low powered hardware, but unfortunately not very popular simply due to the fact that it’s not very popular. There were a few Forth-based microcomputers built in the 1980s, but these were largely unsuccessful.

[Leon] is a Forth aficionado and came up with his own Forth development board in the hopes of Forth making a comeback. It’s a very small and cheap board – only about $12 in parts – but it’s still extremely powerful and a fun platform for investigating Forth.

Compared to other programming languages found in 80s microcomputers, Forth is just weird. It’s a stack-based language, so instead of adding two numbers like 3 + 4, Forth uses postfix notation (or Reverse Polish Notation) so the same statement is expressed as 3 4 +. It’s a much more efficient way for computers to handle data, and some claim it’s more efficient for humans as well.

[Leon] created his own board able to be programmed in Forth, shown above, that uses an ATMega328 microcontroller. He’s using AmForth to put Forth on his system, but also extended the base AmForth install with his own floating point version. making this version of Forth at least as powerful as any 80s microcomputer or ATMega development board is today.

[Leon] put together a great demo of the capabilities of Forth and his dev board. You can check that out below.

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Humidity Activated Bathroom Fan

bathroom humidifier

[Andrea] recently moved into an apartment with a few of his friends. Unfortunately the bathroom lacks one of the most important things — A fan. Or at least a window!

Using the case of an air freshener, a simple DHT11 Humidity/Temperature sensor, an LCD, a 12V fan, and ATmel328 microcontroller, he created this handy gadget.

When the humidity in the bathroom passes the 50% threshold, an LED flashes to prompt the user to open the door. After a short delay, one of the transistors flips causing the moist air to circulate out of the room.

We’re surprised the little 12V fan is powerful enough to clear the room, but apparently it helps a lot and can clear the room in less than 20 minutes.

To see it in action, stick around after the break.

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An atmega328-based radioteletype XY scope display

[Jack] tipped us about a Crossed Bananas Display (CBD) he just designed. A CBD is a tuning aid for frequency-shift keyed (FSK) modes and is basically an oscilloscope in X-Y mode. At one time, radioteletype operators used binary FSK to transmit text over radio waves. In this scheme, the “1” is called the mark frequency and the “0” is called the space frequency. If both frequencies were perfectly tuned (correct phase) the resulting display would look like the one shown above, explaining the origin of the “crossed banana” name.

The build is based on an ATmega328 and a 1.8″ ST7735R display which has a 128×160 resolution. The MC33204PG operational amplifier is used in conjunction with a potentiometer to scale the input in the microcontroller ADC’s range. Another potentiometer sets the refresh rate of the graph. The whole project is enclosed in a painted cast-aluminium bud box and all the sources for this project can be found here.

Breadboard Sequencer Does a Lot with Very Little Hardware

breadboard-sequencer

[Jan Cumpelik] squeezes a lot of performance out of very few components with his breadboard sequencer which he calls Lunchbeat. We really like his awesome breadboard which has a series of trenches perpendicular to the bus strips framing the long sides. All of our breadboards have just one trench down the middle. This, combined with his mad breadboard skills, results in a really clean prototype.

The chip nearest his hand is the ATmega328 which drives the sequencer. It takes inputs from that row of 10k trimpots as well as a series of tactile switches. Feedback is given with the row of eight LEDs. Those are driven from a 595 shift register to save pins on the microcontroller. The remaining chip is an OpAmp which works in conjunction with a 3-bit R2R ladder DAC to output audio. Turn your speakers down just a bit before taking in the demonstration below. There you will also find an image version of his schematic that we made for your convenience. It is only available as a PDF in the code repository he posted.

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ContactKey: A portable, battery-powered phonebook

contactKey

Although it’s still a prototype, [Russell] tipped us off to his battery-powered device for storing your contacts list: ContactKey. (Warning: Loud sound @ beginning). Sure, paper can back up your contact information, but paper isn’t nearly as cool to show off, nor can it receive updates directly from your Android. The ContactKey displays a contact’s information on an OLED screen, which you can pluck through by pressing a few buttons: either ‘Up,’ ‘Down,’ or ‘Reset’. Although the up/down button can advance one contact at a time, holding one down will fly through the list at lightning speed. A few seconds of inactivity causes a timeout and puts the ContactKey to sleep to conserve battery life.

This build uses an ATMega328 microcontroller and an external EEPROM to store the actual list. [Russell] wrote an Android app that will sync your contact list to the ContactKey over USB via an FTDI chip. The microcontroller uses I2C to talk to the EEPROM, while an OLED display interfaces to the ATMega through SPI. We’re looking forward to seeing how compact [Russell] can make the ContactKey once it’s off the breadboard; the battery life for most smartphones isn’t particularly stellar. Phones of the future will eventually live longer, but we bet it won’t be this one.

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