Z80 Family Reunion Discovered In Old PoS Card Swiper

June 14, 2021 by Chris Lott 19 Comments

[Ben Heck] found an old card-swipe point-of-sale box at the Goodwill store, took it home, and tore it down to see what was inside. He found a completely serviceable single board computer based on the Z80. In fact, there’s a whole family of four Z80 chips: the CPU itself, the DART chip (dual UART), the PIO chip (parallel input/output interface), and the CTC chip (counter/timer circuit). That’s not all — there’s a landline telephone modem, a real time clock, 32K of RAM and UV-EPROM. The second PCB of this assembly holds a hefty sixteen-key keypad and a sixteen-character vacuum fluorescent alphanumeric display. All this for the bargain price of $2.99.

Surely [Ben] will dig into the Z80 system in the future, but in this video he tries to make the display work. An OKI Semiconductor controller drives the VFD. After tracking down the data sheet, [Ben] wires it up to an Arduino and writes a quick program. Only a few YouTube minutes later, he conquers the display, drawing sample text anywhere he wants on the screen with any brightness he desires.

You never know what you may find lurking inside old equipment like this. You might find a proprietary ASIC with no documentation, or like [Ben] did here, you could find a fully functioning embedded computer. If [Ben] can whip up a RAM-based emulator to replace the 32K UV-EPROM, he’ll have a perfect evaluation board for Z80 projects.

Let us know in the comments if you have found any treasures like this. Also, how would you use this board if you had found it? Thanks to reader [Nikša Barlović] for sending in the tip.

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Mickey’s Big Timer Makes Glider Competitions Better

June 13, 2021 by Zoe Skyforest 2 Comments

There’s plenty of obscure sports in the world. Many of them could benefit from bespoke equipment like scoring displays, but are too obscure to support commercial efforts in this regard. Radio controlled glider competitions fit into just this category. This led a man named [Mickey] to develop what he calls Mickey’s Big Timer, to aid in the running of such events.

Glider events run outdoors in full sunlight, so the system uses big bright LED matrix displays to show its timing information. The system, built around the STM32 Discovery platform, uses several of the microcontroller boards to drive several displays as well as the main controller which handles timing. It also packs in an audio system for issuing instructions to competitors. It can also display pilot names as well as instructions such as when competitors should land at the end of a heat.

Some code is available on Github for those interested in how it all works. Word around the RC forums has it that [Mickey] built several systems, some of which ended up as far afield as New Zealand where they helped run many successful glider contests over the years.

We’ve seen plenty of scoreboard projects over the years; a little portable one could be useful for adding some spice to your pickup neighbourhood games. Video after the break.

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Hacking The Lidl Home Gateway

June 12, 2021 by Jenny List 21 Comments

For years, Europeans have been browsing the central aisles of the German Aldi and Lidl supermarket chains, attracted by the surprising variety of transitory non-grocery bargains to be found there. There are plenty of temptations for hackers, and alongside the barbecues and Parkside tools at Lidl last year was a range of Zigbee home automation products. Every ZigBee network requires some form of hub, and for Lidl this comes in the form of a £20 (about $28) Silvercrest Home Gateway appliance. It’s a small embedded Linux computer at heart, and [Paul Banks] has published details of how it can be hacked and bent to the user’s will.

Under the hood is a Realtek RTL8196E MIPS SoC with 16Mb of Flash and 32 Mb of memory. Gaining control of it follows the well trodden path of finding the bootloader, dumping the firmware, and re-uploading it with a known password file. If you’ve done much hacking of routers and the like you’ll recognise that this quantity of memory and Flash isn’t the most powerful combination so perhaps you won’t be turning it into a supercomputer, but it’s still capable enough to be integrated with Home Assistant rather than the cloud-based services with which it shipped.

There was a time when repurposing routers as embedded Linux machines was extremely popular, but it’s something that has fallen from favour as boards such as the Raspberry Pi have provided an easier path. So it’s good to see a bit of old-fashioned fun can still be had with an inexpensive device.

If you fancy a bit more German budget supermarket goodness, feast your eyes on an Aldi stick welder!

Tiny Mechanical Keyboard, Powered By Pi Pico

June 9, 2021 by Donald Papp 18 Comments

For some applications, smaller is better and that is precisely the thinking behind a diminutive keyboard like the PiPi Gherkin, which is designed to use the Raspberry Pi Pico as its controller. This keyboard may have only 30 keys in total, but they are full-sized for comfort and don’t let the scant layout mislead you. It has more functionality than it would seem to at first glance; the entire bottom row acts as dual function tap/hold keys, allowing the keyboard to shift layers on the fly.

This keyboard definitely has a a thoughtful layout, and we’re not just talking about the tap/shift functionality. We especially like the way the Pi Pico is tucked neatly underneath the main PCB, taking up very little room while exposing its USB connector between two standoffs for easy access without requiring an adapter, or wiring a separate plug.

If the Gherkin sounds familiar, we’ve seen it before as part of this lunchbox cyberdeck build, where the small size allowed it to take up impressively little room. The shifting might take a little getting used to, but it’s a clean design that uses full sized keys, so when it comes to small keyboards one could certainly do worse.

Custom Num Pad Does Double Duty As Macro Pad

June 8, 2021 by Kristina Panos 7 Comments

Why buy a num pad or a macropad when you can build something new and beautiful, open source that bad boy, and be a hero to the community? We think that should be all the justification you ever need to build instead of buy, even if you think your thing is Just Another Keypad [JAnK] as [Clewsy] claims.

At first glance, JAnK appears to be a standard number pad with four macro keys across the top. But when you roll your own ‘board, all the keys are programmable. [Clewsy] took advantage of this by adding a second layer that’s accessible with (what else?) the Num Lock key. This switches JAnK over to 21-key macro pad mode.

[Clewsy] rolled their own PCB for this and used the venerable ATMega32u4 because of its HID and USB host capabilities. Every key is backlit, and these LEDs are driven by an MP3202 LED driver and PWM from the AVR. [Clewsy] was able to build a prototype by sawing the num pad off of a stainless steel key switch plate from another build, but eventually ordered JAnK its own custom, laser-cut, stainless steel plate. The lovely enclosure is made of spotted gum wood and an acrylic base.

Putting it all together proved to be a bit problematic. [Clewsy] soldered up the minimum viable components for testing and discovered that the ATMega’s VCC and GND pins were both shorted. This killed the AVR programmer, but not the chip itself, and [Clewsy] happened to have a spare. To add insult to injury, the Num Lock light didn’t work, but [Clewsy] was able to simply reverse the LED instead of ordering a new pile of boards. Check out the detailed write-up with code and tons of pictures over on [Clewsy]’s personal site.

One of the awesome things about this build is that [Clewsy] was able to re-use the code from macr0, which began life as a proof of concept for scanning key matrices, and retired to become a music and media controller.

Gdbdiff: Diff-ing A Real RP2040 MCU Against An Emulated MCU

June 3, 2021 by Maya Posch 15 Comments

What to do when developing an RP2040 emulator but validating the emulator instruction by instruction is a slow and tedious process? Why, automatically compare it against the real hardware if you’re [Uri Shaked], of course. This is the purpose of gdbdiff. This project uses the GDB remote serial protocol via OpenOCD to run test firmware step by step.

During a livestream (video linked via the above link), this allowed [Uri] to find a number of instruction bugs in the emulator this way. These issues involved issues such as incorrect flags in the APSR register and an edge case in the LSRS register. This gdbdiff livestream is part of an entire series of live-coding sessions during which [Uri] writes an RP2040 emulator from scratch.

We applaud [Uri] for creative thinking here, and assume that this way the livestream was probably more entertaining to watch than when doing instruction-level debugging purely by hand :)

New Part Day: RP2040 Chips In Single Unit Quantities

June 1, 2021 by Jenny List 27 Comments

Since the launch of the Raspberry Pi Pico back in January the little board with its newly-designed RP2040 microcontroller has really caught the imagination of makers everywhere, and we have seen an extremely impressive array of projects using it. So far the RP2040 has only been available on a ready-made PCB module, but we have news today direct from Eben Upton himself that with around 600k units already shipped, single-unit sales of the chip are commencing via the network of Raspberry Pi Approved Resellers.

This news will doubtless result in a fresh explosion of clever projects using the chip, but perhaps more intriguingly it will inevitably result in its appearance at the heart of a new crop of niche products that go beyond simple clones of the Pico in different form factors. The special ingredient of those two PIO programmable state machines to take the load of repetitive tasks away from the cores raises it above being merely yet another microcontroller chip, and we look forward to that feature being at their heart.

The Broadcom systems-on-chip that power Raspberry Pi’s existing range of Linux-capable boards have famously remained unavailable on their own, meaning that this move to being a chip vendor breaks further new ground for the Cambridge-based company. It’s best not to think of it in terms of their entering into competition with the giants of the microcontroller market though, because a relative minnow such as the RP2040 will be of little immediate concern to the likes of Microchip, ST, or TI. A better comparison when evaluating the RP2040’s chances in the market is probably Parallax with their Propeller chip, in that here is a company with a very solid existing presence in the education and maker markets seeking to capitalise on that experience by providing a microcontroller with that niche in mind. We look forward to seeing where this will take them, and we’d hope to eventually see a family of RP2040-like chips with different package and on-board peripheral options.