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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Pair of MIDI dongles to inspire some weekend music hacking

pair-of-midi-dongles

This pair of dongles is a fun way to get your feet wet working with MIDI hardware. They’re called MIDIvampire-I and MIDIvampire-II. Just plug one end into your MIDI-ready instrument and the other into a pair of speakers and you’re off and running. Mark I is a polyphonic synth, and Mark II is a drum machine, but both use basically the same hardware which you may already have on hand.

The single chip on each board is an ATmega328 often found anchoring Arduino boards. The other silicon component is an S1112B30MC voltage regulator. The rest of the components are passives, with MIDI and headphone jacks for connectivity. They’re selling these if you want the easy way out, but we thought we’d bring them to your attention in case you needed a breadboarding project this weekend. The firmware, BOM, schematic, and board artwork are all available on the Wiki pages linked in the articles above. After the break you can see a couple of demo videos which walk through all of the features.

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Soundball bumps to your tunes

soundball-blinks-to-the-music

Meet soundball, a hobby electronics project when replaces a disco ball with one made of LEDs (translated) going every which way. This image shows the device before being injected into an enclosure. The final offering is a white project box with a hole in the top through which the diffuser covered blinky ball is supported.

The main board hosts a collection of the usual suspects: an ATmega328, an MSGEQ7 equalizer, a couple of TLC5940 LED drivers, and a footprint for a Bluetooth Shield. The equalizer chip provides [Cornelius] the audio analysis used to generate light patterns that go along with the music.  But he can still control the lights manually with a button on the case or by connecting to it via Bluetooth.

Swap out the LED drivers for some solid state relays and you can blink your Christmas lights to the music.

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