MIDI out for a Korg CX-3 organ


[Michael] loves this old organ of his, but recently he wondered if it would be possible to add MIDI out without altering its original functionality. With a bit of research and more than a bit of hard work he accomplished his goal.

The nice thing about working on a quality piece of hardware like this is the resources you can find regarding how they work (which we bet is tailored for how to repair them when they break). [Michael] found a website with plenty of info on the circuit boards and how they work. From this he was able to locate a few chips which stream serial data regarding which keys have been pressed. Bingo!

Once he located the three signals he was after he built a board to translate them to the MIDI protocol. His circuit is based around an ATtiny2313. It is supported by a liner voltage regulator circuit as well as a buffer chip which converts the incoming signals to the 5V levels needed. His home etched board is clean and well mounted, and the success of the project can be heard in the clip after the jump.

Continue reading “MIDI out for a Korg CX-3 organ”

ATtiny2313 frequency meter measures 1Hz-10MHz


This frequency meter project squeezes a lot of performance out of the ATtiny2313 microcontroller. That chip does all of the work, measuring the frequency on the input pin as well as multiplexing the set of 7 seven-segment displays which read out the measurement.

The system is only as accurate as the clock crystal used by the AVR chip, so [Manekinen] recommends using one with the best tolerances available. It is also necessary to choose a value which is divisible by 1024 to get the best combination of accuracy and resolution. In this case he’s using a 22.1184 MHz crystal oscillator which is a slight overclocking of the chip which is spec’d to run at 20 MHz max.

We didn’t totally follow his explanation of how the two timers are used for counting. But if we really wanted to drill down for a full understanding his code (written in BASCOM-AVR) is available. If you’re just interested in the hardware we embedded a screenshot of the schematic after the break.

Continue reading “ATtiny2313 frequency meter measures 1Hz-10MHz”

The Keypad Contest


What can you do with ten buttons and ten lights? A lot.

[Andrew] and [Nathan] found a collection of Hale Research keypads being thrown out, and decided to host the Keypad Contest. The goal of the contest was to create something nifty using the ten buttons and ten lights on the keypad, and an ATtiny2313 that replaced the original 8051-compatible microcontroller in the device.

[Andrew] wanted to try making PCBs with his home-built CNC machine, so he milled out USBtinyISP programmers for the ATtiny2313. Then he gave out eleven development kits to a group, and explained how to develop on the hardware.

After a month of hacking, seven people completed projects. The winner was an internet radio controller, which had the keypad sending serial data to a TP-Link WR703N router. The router used a USB sound card and OpenWRT firmware to stream music. The runner up was a timing game called “Capture”.

The contest write up has details on all seven projects. [Andrew] and [Nathan] were successful in getting software engineers to try hardware with this contest, resulting in some neat hacks. After the break, check out a video demo of the internet radio controller.

Continue reading “The Keypad Contest”

Glass delay line slide used in an RGB lamp


The spire used in this lamp is a part from an old television. It’s a glass delay line slide which pipes the light up from the Bluetooth controlled RGB lamp (translated) in the base.

We have looked at delay lines previously when [Dave Jones] tore down a camcorder to get at one. But we must have missed the EEVblog follow-up episode which explains how the glass slides work. The device uses physical distance to form a delay. Waves directed into the edge of the glass slide bounce around at an angle before being sensed at the collection point. [Lukas] liked the visual appearance of the part and decided to use it to add visual interest to his lamp project. The nature of the glass makes it perfect for directing the light up and away from the PCB.

The lamp consists of one RGB LED module controlled by an ATtiny2313 microcontroller. Also on board is a HC-05 Bluetooth module. This along with an app he wrote lets the user change lamp color and behavior wirelessly. You can see the lamp in action in the video after the break, but we think the camera shot probably doesn’t do it the justice it deserves.

Continue reading “Glass delay line slide used in an RGB lamp”

WAV music player uses an ATtiny

We’re very accustomed to seeing small media player builds, but [txyz]’s ATtiny-powered audio player is one of the smallest and most feature-packed we’ve seen.

The audio player is powered by the very small and very inexpensive ATtiny2313. The music is stored on an SD card – a maximum of 2GB of WAV files recorded in mono at 32kBps at an 8-bit depth. On boot, the ATtiny loads the first audio file from the card and outputs it through a speaker connection.

To make things interesting, [txyz] made the audio player controllable via a serial connection. Once a small FTDI adapter is connected to the player, [txyz] can connect to it through a terminal and run through his playlist.

Even though the player is controllable through a serial port, there are a few pins left over that [txyz] could attach to buttons, if so desired. With a battery pack, this would turn his music player into the homebrew equivalent of an iPod shuffle. With the low component count, it might actually be cheaper than the shuffle, if [txyz]’s time is free, that is.

Video after the break.

Continue reading “WAV music player uses an ATtiny”

LED matrix pendants

If you want to mess around with some microcontrollers but don’t really have a purpose in mind this project is perfect for you. It’s cheap, easy to assemble, and there’s blinking LEDs! [TigerUp] shows us how he  put together some LED matrix pendants using just five components.

He calls the project Tiny Matrix, which is fitting as the pendant outline is barely 0.5″ by 0.7″. On the back an ATtiny2313 chip has been soldered directly to the legs of the LED display. They just happen to line up with I/O pins on the chip which makes for super simple soldering. Power comes from a coin-cell which is connected to the pendant by a red and black wire which make up the necklace for the device. The last two components not yet mentioned are a momentary push switch for changing modes, and a pull-up resistor on the reset pin. The bill of materials rings in at $4 and his firmware offers up nine different modes as you can see in the clip after the break.

[TigerUp] was inspired by this 8×8 matrix project.

Continue reading “LED matrix pendants”

Art Controller: relay board with switches for timing

Meet the Art Controller, a new dev board available over at Evil Mad Scientist Laboratories. It provides a drop-in solution for switching higher voltage loads (but not mains). The thing we like most about it is the ability to alter a switching delay without reprogramming the firmware.

The board uses an ATtiny2313 for control. It’s fed regulated 5V power from the on-board 7805 linear regulator. The relay can handle a 24V DC or 40V AC load, which is targeted at an audience that needs electronic switching for art-related devices but doesn’t want the hassle of designing a circuit every time. This offers a single shot, or repeat action, with that bank of DIP switches selecting a delay from once every second, to every 31 hours. It can get its initial trigger from anything that can pull a pin low, like a button, or a coin acceptor.

Keep this in mind. The open source nature of the project means it could come in handy as a reference design.