Minimal Computer and Operating System: One Button, One LED

DUO BINARY is a very, very small computer system in every possible sense. It runs on an ATtiny84, which has even got “tiny” in its name. The user interface is a single button for data entry and a single LED for feedback, making this binary keyboard look frivolously over-complicated. It uses a devilish chimera of Morse code and a truncated ASCII to enter data, and the LED blinks the same back at you.

We’re guessing that [Jack Eisenmann] is the only person in the world who can control this thing, and you can watch him doing so in the video embedded below. Continue reading “Minimal Computer and Operating System: One Button, One LED”

Morse Code: Paris in the Mint Box

TinyLilyThumbnail[Rob Bailey] likes to build things and he likes ham radio. We are guessing he likes mints too since he’s been known to jam things into Altoids tins. He had been thinking about building a code practice oscillator in a Altoids Smalls tin, but wasn’t sure he could squeeze an Arduino Pro Mini in there too. Then he found the TinyLily Mini. The rest is history, as they say, and 1CPO was born.

The TinyLily Mini is a circular-shaped Arduino (see right) about the size of a US dime. most of the pads are arranged around the circle and there is a small header that takes a USB programmer. A small rechargeable battery can run the device for a long time.

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Morse Code Waterfall is Cooler Than Your Fifth Grade Science Fair Project

For her science fair project, [David]’s daughter had thoughts about dipping eggs in coffee, or showing how dangerous soda is to the unsuspecting tooth. Boring. Instead she employed her father to help her build a Morse Code waterfall.

A more civilized wea-- tool from a more elegant age. Young Jed--engineer.
A more civilized wea– tool from a more elegant age. Young Jed–Engineer.

[David] worked with his daughter to give her the lego bricks of knowledge needed, but she did the coding, building, and, apparently, wire-wrapping herself. Impressive!

She did the trick with two Arduinos. One controls a relay that dumps a stream of water. The other watches with an optical interrupt made from an infrared emitter and detector pair to get the message.

To send a message, type it in the keyboard. The waterfall will drop spurts of water, and then show the message on the decoder display. Pretty cool. We also liked the pulse length dial. The solution behind the LEDs is pretty clever. Video after the break.

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Spark Gap and Coherer Meet Beagle Bone

Getting back to basics is a great way to teach yourself about a technology. We see it all the time with computers built from NAND gates or even discrete transistors. It’s the same for radio – stripping it back to the 19th century can really let you own the technology. But if an old-school wireless setup still needs a 21st-century twist to light your fire, try this spark gap transmitter and coherer receiver with a Beagle Bone Morse decoder.

At its heart, a spark gap transmitter is just a broadband RF noise generator, and as such is pretty illegal to operate these days. [Ashish Derhgawen]’s version, which lacks an LC tuning circuit, would be especially obnoxious if it had an antenna. But even without one, the 100% electromechanical transmitter is good for a couple of feet – more than enough for experimentation without incurring the wrath of local hams.

The receiver is based on a coherer, a device that conducts electricity only when a passing radio wave disturbs it. [Ashish]’s coherer is a slug of iron filings between two bolts in a plastic tube. To reset the coherer, [Ashish] added a decoherer built from an electromagnetic doorbell ringer to tap the tube and jostle the filings back into the nonconductive state. He also added an optoisolator to condition the receiver’s output for an IO pin on the Beagle, and a Python script to decode the incoming Morse. You can see it in action in the video below.

If this build looks familiar, it’s because we’ve covered [Ashish]’s efforts before. But this project keeps evolving, and it’s nice to see where he’s taken it and what he’s learned – like that MOSFETs don’t like inductive kickback much.

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Breathing New Life Into An Old Key

For most of us who have experimented with Morse code, the oldest key we are likely to have used will have been a piece of military surplus kit from the Second World War era. [Kyle Gabriel] however is a lucky man. His grandfather left him his key-on-board telegraph practice set, a vintage key and telegraph sounder arrangement used to learn Morse code in the days when the telegraph was king. Rather than keep the set merely as an heirloom, [Kyle] set about bringing it up to date by interfacing it to a Raspberry Pi and writing a Morse reader program.

Along the way [Kyle] had to contend with debouncing the switching signal from the key, considering an RC network before settling on a software debounce timer. He provides a brief synopsis of the mechanics of Morse decoding software, and a demonstration of the code in action which you can see in the video below the break.

[Kyle’s] decoding software, beatbybeat, is on GitHub. We can see it will be a useful tool for anyone interested in Morse, or who is writing their own Morse software.

Morse code has featured on these pages more than a few times over the years. Of relevance to this piece are an Arduino decoding Morse code, a more up-to-date practice oscillator with a home-made key, and a couple of other vintage telegraphs reading RSS feeds and reading emails.

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Tiny USB Morse Code Beacon

It is reasonably easy to make a microcontroller spit out some Morse code. What makes [pavlin’s] take on this project interesting is that it resides on a tiny USB board with an ARM processor. The design for the board is available with single-sided artwork suitable for production using simple methods like toner transfer.

The STM device has a built-in USB bootloader. It can also act as a serial port, which makes the project very simple. The only external parts are a speaker and an optoisolator. The program provides a command line interface over the serial port that you can use to program the message and set other options like speed and the delay between messages. The code is available on GitHub.

You might argue that a beacon shouldn’t need a USB port, and we’ve seen an alternative that fits the bill. If you want a much larger Arduino-based keyer, we’ve seen those, too.

Free Cell Data Transfer with Slowest Morse Code Ever

Readers of a certain age will remember the payphone trick of letting the phone ring once and then hanging up to get your quarter back. This technique was used with a pre-planned call time to let someone know you made it or you were okay without accruing the cost of a telephone call. As long as nobody answered you didn’t have to pay for the call, and that continues to be the case with some pay-per-minute cellphone plans.

This is the concept behind [Antonio Ospite’s] ringtone data transfer project called SaveMySugar. Don’t judge him, this work has been ongoing for around ten years and started back when cellphone minutes were a concern. We’re just excited to see that he got the excruciatingly slow thing to work.

Those wanting to dig down to the nitty-gritty of the protocol (and you should be one of them) will want to read through the main project page. The system works by dialing the cellphone, letting it ring once, then hanging up. The time between redials determines a Morse code dot, dash, or separation between characters. Because you can’t precisely determine how long it will take each connection to read, [Antonio] built ‘noise’ measurement into the system to normalize variations. The resulting data transfer works quite well. He was able to transfer the word “CODEX” in just six minutes and thirty seconds. But it is automatic, so what do you care? See the edge-of-your-seat-action play out in the video below.

If you can’t stomach that baud, here’s a faster Morse code data transmitter but it doesn’t use the phone.

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