A Unique Display Makes An Unusual Clock

Do you know the clock speed of the computer you’re reading this article on? Maybe Hackaday readers are more likely to reply “Yes!” to that question than the general public, but if there’s a takeaway it’s that for most computer users their clock speed is now an irrelevance. It’s quick enough for the job in hand and that’s all that matters. This was not always the case though, and a few decades ago the clock speed of a PC was its major selling point. Beige boxes would have seven-segment displays lit up with the figure, and it was an unusual example of one that [Ken Yap] used to produce a clock that he believes is one-of-a-kind; unless by some slim chance somebody else has rescued the same part.

The displays were hard wired without any signals from the processor, and what makes this one unusual is that as well as having a couple of digits in yellow it also sports a segmented “MHz” in red. This would have been quite a big deal on your 486 back in about 1994. To make a clock from this unpromising start required a little creative thinking, and he manages it by using the “M” and the “H” digits to represent minutes and hours, and displaying each figure in turn. The display is wired on a piece of protoboard with an STM8 dev board, and yes, as you can see in the very short video below the break, it does tell the time.

Custom displays are more usually seen in the world of LCDs than LEDs, so this one remains a rarity on these pages. Happily there are projects out there in which people spin their own takes on the idea.

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Pulse Generator Does The Job With An STM8

When working with hardware, whether a repair or a fresh build, it’s often necessary to test something. Depending on what you’re working with, this can be easy or a total pain if you can’t get the right signal to the right place. To eliminate this frustrating problem, [WilkoL] built a useful pulse generator for use in the lab.

[WilkoL] notes that historically, the job of generating pulses of varying length and frequency would be achieved with a smattering of 555 timers. While this is a perfectly cromulent way to do so, it was desired to take a different approach for the added flexibility modern hardware can offer. The pulse generator is instead built around an STM8 microcontroller; an unusual choice in this era, to be sure. [WilkoL] specified the part for its incredibly low cost, and highly capable timer hardware – perfect for the job.

Combined with an ST7735 TFT LCD screen, and programmed in bare metal for efficiency’s sake, the final project is installed in a project box with controls for frequency and pulse length – no more, no less. Capable of pulse lengths from 250 ns to 90 s, and frequencies from 10 mHz to 2 MHz, it’s a tool that should be comfortable testing everything from servos to mechanical counters.

Of course, if you need to get down to picosecond timescales, an avalanche pulse generator might be more your speed. Video after the break.

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Palm-Sized Sixteen Segments Light The Way To Our Hearts

It’s no secret that we here at the Hackaday are suckers for cool display. LEDs, OLEDs, incandescent, nixie or neon, you name it and we want to see it flash. So it fills us with joy to discover a new way to build large, daisy-chainable 16-segment digits, and even more excited to learn how easy they are to fab and assemble.

A cousin of the familiar 7 segment display, the 16 segment gives so many more possibilities (128% more possibilities to be exact) for digit display. To be specific, those extra segments unlock the ability to display upper and lowercase latin characters as well as scads of punctuation.

But where the character set is complex, the assembly is anything but thanks to a great design from [Kolibri] called klais-16. They’re available fully assembled if you want to jump straight to code, but thanks to thorough documentation (seriously, check this out) assembly is a snap.

Each module is composed a very boring PCBA base layer which should be inexpensive from the usual sources, even when ordering one fully assembled. A stackup of three more PCBs are used for spacing and diffusion with plans for die-cut or injection mold layers if a larger production run ends up happening. Board dimensions for each character are 100 mm x 66.66 mm (about 4″ x 2.5″). Put together, each module can stand on its own or be easily daisy-chained together to make a longer single display.

Addressing all those bits with an elaborate, ugly control scheme would be a drag but fortunately the firmware for the onboard STM8 microcontroller exposes a nice boring serial interface which can be used without configuration to display strings. There’s even an example Windows Batch script!

The Cheap Way To Glitch An STM8 Microcontroller

Reverse engineering or modifying a device often requires you to access the firmware stored on a microcontroller. Since companies are usually not fond of people who try to peek into their proprietary data, most commercial devices are readout protected. [rumpeltux] ran into this problem when he tried to dump the firmware on an HC-12 wireless serial communication module for yet undisclosed reasons. Hacking into the device was a challenge that he gladly accepted and in the end, he succeeded by building a low-cost setup for voltage glitching.

Voltage glitching is a form of fault injection that has, e.g., been successfully used to hack the Playstation Vita. It involves the injection of voltage spikes on the power line in order to force the bootloader to skip security checks. The hard thing is trying to find the right shape of the waveform and the best way to inject the signal.

While there are already open-source boards for fault injection like ChipWhisperer, [rumpeltux] chose to build his own setup around an FPGA. By using a cheap EPM240 board, some MOSFET, and a USB-to-Serial converter, the total costs of the glitching setup were under 20 Euros. [rumpeltux] then recorded a larger number of voltage traces on the VCC pin around the reset phase and analyzed the differences. This helped him to pinpoint the best time for injecting the signal and refine the search space. After some unsuccessful attempts to glitch the VCC and GND pins, he got lucky when using one of the voltage regulator pins instead.

Be sure not to miss Samy Kamkar’s talk at Supercon 2019 if you want to know more about hardware attacks or how to eavesdrop on people using a bag of potato chips.

Getting Started With STM8

There are so many different CPUs today and often the hardest thing about using any of them is getting started and gathering the right software tools. If you’ve ever eyed up the very inexpensive STM8 processor, you’ll want to check out [Shane Burrell’s] video (see below) about how to get started with the STM8.

The STM8 isn’t a 32-bit processor — you could probably guess that from the name. [Shane] uses SDCC (small device C compiler) to target the little chip. He also shows how he manages a fairly substantial piece of code and how he controls the build process.

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Hackaday Prize Entry: HID Dial

Microsoft has introduced a few interesting bits of hardware recently, and the most drool worthy by far is the Microsoft Surface Dial. What is this magical input device that will revolutionize creative work on a computer? Basically, it’s a Griffin PowerMate — a rotary encoder and button — an interface that really hasn’t changed in a decade and a half.

[K.C. Lee] figures a device this simple would make for a great Hackaday Prize entry, so he built a USB HID multimedia dial. It’s a rotary encoder and a button. This one lights up, though, making this a gamer USB HID multimedia dial.

The electronics for this build are based around the STM8S003, an extraordinarily cheap microcontroller that will work well enough in this application. The mechanical part of this build is a little more interesting; [K.C.] says not everyone has access to fancy CNC or 3D printing equipment, so he built this model out of bits of plastic, metal, and superglue. This enclosure is literally an old superglue bottle cap, an empty dental floss spool, and bits of metal. It works, and took less time to build than it would take to design in a CAD program.

Right now, [K.C.] is working through some USB issues with the STM8 microcontroller. Once those issues are behind him, he’ll have a very cool and very useful input device sitting on his desk. It might look like parts waiting for the recycling bin, but it will be at least as useful as the fancy Microsoft version.

Smaller Cheaper Arduino

Well, honestly, [Michael Mayer’s] STM8 Arduino (called Sduino) isn’t actually much to do with the Arduino, except in spirit. The STM8 is an 8-bit processor. It is dirt cheap and has some special motor control features that are handy. There’s a significant library available for it. However, it can be a pain to use the library and set up the build.

Just like how the Arduino IDE provides libraries and a build system for gcc, Sduino provides similar libraries and a build system for the sdcc compiler that can target the STM8. However, if you are expecting the Arduino’s GUI or a complete knock off of the Arduino library, you won’t get that.

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