Single Board Relay Computer

We all know you can build a computer out of relays, and if you’re a regular reader of Hackaday, you’ve probably seen a few. Actually designing and fabricating a computer built around relays is another thing entirely, and an accomplishment that will put you right up there with the hardware greats.

The newest inductee of the DIY microcomputer hall of fame is [Jhallen]. He’s built a microcomputer ‘trainer’ out of relays. It’s got more click and clack than the Tappet family, and is a work of art rendered in DPDT relays.

The biggest consideration in designing a relay computer is the memory. You can implement a CPU in a few dozen relays, but even a small amount of memory is still hundreds of additional components. In this computer, [Jhallen] is sort of cheating. The memory is implemented as 256 32-bit words on a microcontroller alongside a controller for the front panel. The CPU is still all relays, with support for self-modifying code, a bunch of instructions for conditional jumps, and an ‘increment and jump if not equal to zero’ instruction.

Below, you can check out a very in-depth video of the relay computer in action, starting off with some satisfying click and clack of Euclid’s algorithm and a demonstration of the variable clock rate. The video goes on to demonstrate the assembly language of the relay computer itself and a bit of the overall architecture. This is really one of the most educational demo videos for vintage computing we’ve ever seen.

[Jhallen] assembled a few of these boards and he’s selling some of the extras. If you have $600, you can pick one up over on Tindie (standard Hackaday / Tindie disclosure statement). Considering the amount of soldering required to assemble this board, we’re going to guess that’s a very fair price.
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A Smaller, Cheaper RISC V Board

Early this year, the world of electronics saw something amazing. The RISC-V, the first Open Source microcontroller was implemented in silicon, and we got an Arduino-derived dev board in the form of the HiFive 1. The HiFive 1 is just a bit shy of mindblowing; it’s a very fast microcontroller that’s right up there with the Teensy when it comes to processing power. There’s support for the Arduino IDE, so all those fancy libraries are ready to go. That’s not to say there aren’t a few problems; it’s a relatively expensive board, and it does use the ubiquitous but somewhat unfortunate Arduino form factor.

In the past few months, SiFive, the folks behind the FE310 microcontroller inside the HiFive 1, have been working to get bare chips out on the market. Now, those trays of microcontrollers are being turned into newer, slightly more development-friendly boards. Meet the LoFive RISC-V. It’s a GroupGets crowdfunding campaign from [Michael Welling], and it takes all the openness from the HiFive 1 and the FE310 microcontroller and stuffs it into a cheap, easy-to-use board.

Like the HiFive 1, the LoFive features the FE310 microcontroller and a 128 Mbit SPI flash. Unlike the HiFive 1, there’s not much else on this board. There’s a few voltage regulators, a crystal, some caps, and a button on an interrupt pin. If you’re looking for an Open Source microcontroller development board without a lot of cruft, here you go. This is a RISC-V microcontroller with the minimum amount of support circuitry.

The GroupGets campaign is offering up 1,000 of these little boards for $25 each plus shipping. If you’ve been looking for an excuse to play around with Open Source microcontrollers, this may be the best chance you’re going to get for a while.

A Slew Of NYC Meetups With Tindie And Hackaday This Week

This is a busy, busy week for Tindie and Hackaday. We’re going to New York, and we have a ton of events planned.

First up is the monthly Hackaday meetup. This time, we’re teaming up with Kickstarter for a pre-Maker Faire Meetup. We’ll be hosting this at Kickstarter’s HQ, and already we have an impressive line of speakers set up to talk about Assistive Technology. These speakers include:

  • Anita Perr and R. Luke Dubois from the NYU Ability Project
  • Andrew Chepaitis from ELIA Life Technology

Also on deck for the for the Hackaday x Kickstarter meetup are live demos from WearWorks, who are developing the WAYBAND, a haptic navigation device and from Elia Frames, a tactile reading system.

The Hackaday x Kickstarter meetup will be Thursday, September 21st, starting at 6:30pm. Here’s the link to RSVP.

This weekend is also World Maker Faire New York and Tindie will be out in force showcasing all the wonderful bits and bobs developed by the Tindie community.

On deck will be [Jasmine] and [Brandon] from Tindie, and of course we’re inviting Tindie sellers to drop by the booth throughout the weekend and showcase their wares.

Also on deck for the World Maker Faire will be [Shulie], [Shayna] and myself. We’ll be tossing brand new Tindie stickers into the audience and giving out Tindie Blinky Badges. If you’ve ever wanted to show your enthusiasm for DIY hardware, now you can with an electronic blinky lapel pin. Solder it up and listen to Benchoff rationalize why it doesn’t need a current limiting resistor! Such fun!

Better Stepping With 8-Bit Micros

The electronics for motion control systems, routers, and 3D printers are split into two camps. The first is 8-bit microcontrollers, usually AVRs, and are regarded as being slower and incapable of cool acceleration features. The second camp consists of 32-bit microcontrollers, and these are able to drive a lot of steppers very quickly and very smoothly. While 32-bit micros are obviously the future, there are a few very clever people squeezing the last drops out of 8-bit platforms. That’s what the Buildbotics team did with their ATxmega chip — they’re using a clever application of DMA as counters to drive steppers.

The usual way of driving steppers quickly with an ATMega or other 8-bit microcontroller is abusing the hardware timers. It’s quick, but there is a downside. It takes time for these timers to start and stop, and if you’re doing it two hundred times per second with four stepper motors, that clock jitter will ruin your CNC machine. The solution is to use a DMA channel to count down, with each count sending out a pulse to a stepper. It’s a clever abuse of the hardware, and the only drawback is the micro can’t send more than 2¹⁶ pulses per any 5ms period. That’s not really an issue because that would mean some very, very fast acceleration.

The Buildbotics team currently has a Kickstarter running for their four-axis CNC controller using this technique. It’s designed for Taig mills, 6040 routers, K40 lasers, and other various homebrew robots. It’s an interesting solution to the apparent end of the of the age of 8-bit microcontrollers in CNC machines and certainly worth checking out.

Hackaday Links: September 17, 2017


Mergers and acquisitions? Not this time. Lattice Semiconductor would have been bought by Canyon Bridge — a private equity firm backed by the Chinese government — for $1.3B. This deal was shut down by the US government because of national security concerns.

[Jan] is the Internet’s expert in doing synths on single chips, and now he has something pretty cool. It’s a breadboard synth with MIDI and CV input. Basically, what we’re looking at is [Jan]’s CVS-01 chip for a DCO, DCF, and DCA), a KL5 chip for an LFO, and an envelope chip. Tie everything together with a two-octave captouch keyboard, and you have a complete synthesizer on a breadboard.

As an aside relating to the above, does anyone know what the cool kids are using for a CV/Gate keyboard controller these days? Modular synths are making a comeback, but it looks like everyone is running a MIDI keyboard into a MIDI-CV converter. It seems like there should be a –simple, cheap– controller with quarter-inch jacks labeled CV and Gate. Any suggestions?

World leaders are tweeting. The Canadian PM is awesome and likes Dark Castle.

Way back in July, Square, the ‘POS terminal on an iPad’ company posted some data on Twitter. Apparently, fidget spinner sales peaked during the last week of May, and were declining through the first few weeks of summer. Is this proof the fidget spinner fad was dead by August? I have an alternate hypothesis: fidget spinner sales are tied to middle schoolers, and sales started dropping at the beginning of summer vacation. We need more data, so if some of you could retweet this, that would be awesome.

Remember [Peter Sripol], the guy building an ultralight in his basement? This is going to be a five- or six-part video build log, and part three came out this week. This video features the installation of the control surfaces, the application of turnbuckles, and hardware that is far too expensive for what it actually is.

Hackaday Prize Entry: You Can Tune A Guitar, But Can You Reference REO Speedwagon?

Just for a second, let’s perform a little engineering-based thought experiment. Let’s design a guitar tuner. First up, you’ll need a 1/4″ input, and some op-amps to get that signal into a microcontroller. In the microcontroller, you’re going to be doing some FFT. If you’re really fancy, you’ll have some lookup tables and an interface to switch between A440, maybe A430, and if you’re a huge nerd, C256. The interface is simple enough — just use a seven-segment display and a few LEDs to tell the user what note they’re on and how on-pitch they are. All in all, the design isn’t that hard.

Now let’s design a tuner for blind musicians. This makes things a bit more interesting. That LED interface isn’t going to work, and you’ve got to figure out a better way of telling the musician they’re on-pitch. This is the idea of [Pepijn]’s Accessible Guitar Tuner. It’s a finalist in The Hackaday Prize Assistive Technology round, and a really interesting problem to solve.

Most of [Pepijn]’s tuner is what you would expect — microcontrollers and FFT. The microcontroller is an ATMega, which is sufficient enough for a simple guitar tuner. The real trick here is the interface. [Pepijn] modulating the input from the guitar against a reference frequency. The difference between the guitar and this reference frequency is then turned into clicks and played through headphones. Fewer clicks mean the guitar is closer to being in tune.

This is one of those projects that’s a perfect fit for the Hackaday Prize Assistive Technology round. It’s an extremely simple problem to define, somewhat easy to build, and very useful. That doesn’t mean [Pepijn] isn’t having problems — he’s having a lot of trouble with the signal levels from a guitar. He’s looking for some help, so if you have some insights in reading signals that range from tiny piezos to active humbuckers, give him a few words of advice.

Hackaday Prize Entry: An Optical Power Meter

This is the type of crowd that’s famous for building their own test equipment. If you need a way to program a flash chip, don’t go out and buy one — you can just build one. Need a spectrum analyzer? You can build that out of copper clad board. For his Hackaday Prize entry, [oakkar7] is building an optical power meter, capable enough to do futzy fiber work, but still completely DIY.

When you get into networking and telecom connections that don’t begin with the letters ‘RJ’, you start to stumble upon SPF transceivers. These ‘small form factor pluggable’ devices are little modular transceivers capable of handling fiber, Gigabit Ethernet, and other slightly weirder bit pipes. When used with fiber, they can measure optical power in dBm and watts, and can be debugged by a UART.

[oakkar]’s optical power meter uses these SPF transceivers, tied together with a fairly simple circuit consisting of an Arduino, a few tact switches, a Nokia LCD, and an FTDI UART. The key in tying all of this together is an Arduino library for SPF and DDM (Digital Diagnostics Monitoring), giving the user access to all the configuration bits in these transceivers.

While the circuit is simple enough to be built on a piece of perfboard, [oakkar] really knocked it out of the park with the enclosure on this one. With just a little bit of laser cut acrylic and a few standoffs, [oakkar] has a device that actually looks professional, and has most of the capabilities of fancier, more expensive tools.