Four jumper wires with white heatshrink on them, labelled VCC, SCL, SDA and GND

The Connector Zoo: I2C Ecosystems

May 4, 2022 by Arya Voronova 56 Comments

I2C is a wonderful interface. With four wires and only two GPIOs, you can connect a whole lot of sensors and devices – in parallel, at that! You will see I2C used basically everywhere, in every phone, laptop, desktop, and any device with more than a few ICs inside of it – and most microcontrollers have I2C support baked into their hardware. As a result, there’s a myriad of interesting and useful devices you can use I2C with. Occasionally, maker-facing companies create plug-and-play interfaces for the I2C device breakouts they produce, with standardized pinouts and connectors.

Following a standard pinout is way better than inventing your own, and your experience with inconsistent pin header pinouts on generic I2C modules from China will surely reflect that. Wouldn’t it be wonderful if you could just plug a single I2C-carrying connector into an MPU9050, MLX90614 or HMC5883L breakout you bought for a few dollars, as opposed to the usual hurdle of looking at the module’s silkscreen, soldering pin headers onto it and carefully arranging female headers onto the correct pins?

As with any standard, when it comes to I2C-on-a-connector conventions, you would correctly guess that there’s more than one, and they all have their pros and cons. There aren’t quite fifteen, but there’s definitely six-and-a-half! They’re mostly inter-compatible, and making use of them means that you can access some pretty powerful peripherals easily. Let’s start with the two ecosystems that only have minor differences, and that you’ll encounter the most! Continue reading “The Connector Zoo: I2C Ecosystems” →

A Great Resource For The Would-Be Pinball Machine Builder

April 29, 2022 by Dave Rowntree 12 Comments

Those of us beyond a certain age will very likely have some fond memories of many an hour spent and pocket money devoured feeding the local arcade pinball machine. At one time they seemed to be pretty much everywhere, but sadly, these days they seem to have largely fallen out of favour and are becoming more of speciality to be specifically sought out. Apart from a few random ones turning up — there’s a fun Frankenstein-themed machine in the Mary Shelley Museum in Bath, England — a trip to a local amusement arcade is often pretty disappointing, with modern arcade machines just not quite scratching that itch anymore, if you ask us. So what’s an old-school hacker to do, but learn how to build a machine from scratch, just the way we want it? A great resource for this is the excellent Pinball Makers site, which shows quite a few different platforms to build upon and a whole ton of resources and guides to help you along the way.

Continue reading “A Great Resource For The Would-Be Pinball Machine Builder” →

Edible Electronics Let Us Hear The Lamentations Of The Chocolate Bunnies

April 19, 2022 by Kristina Panos 12 Comments

Yet another Day of the Chocolate Bunnies has passed by, and what did you do to mark the occasion? You likely kicked back and relaxed, surrounded by whatever you gave up for Lent, but good for you if you mixed chocolate and electronics like [Repeated Failure] did. They created a completely edible chocolate Easter bunny that screams when bitten.

So obviously, the hardest part is figuring out something to build the circuit with that is both conductive and safe to eat. [Repeated Failure] spent a lot of time with carbon oleogel paste, which is made from natural oils and waxes. Not only was it less conductive than [Repeated Failure]’s skin, it came out pitch black and tasted like nothing, which kind of a bonus, when you think about it.

Then came the cake paint, which [Repeated Failure] laced with trace amounts of silver powder. While that worked somewhat better, a successful circuit would have likely required near-fatal amounts of the stuff. Yikes!

The winner turned out to be edible silver leaf, which is like gold leaf but cheaper. Ever had Goldschläger? Gold leaf is what’s suspended inside. The really nice thing about silver leaf is that it comes in thin sheets and can easily be cut into circuit traces with scissors and connected to I/O pins with copper tape. Be sure to check it out after the break, including [Repeated Failure]’s friend’s reaction to innocently biting the chocolate bunny’s ears off, as one tends to do first.

Think you’d rather hear plants giggle? Sure, it sounds cute, but it’s actually kind of creepy.

Continue reading “Edible Electronics Let Us Hear The Lamentations Of The Chocolate Bunnies” →

Best Ways To Make PCB Breakaway Tabs, Revealed

April 9, 2022 by Donald Papp 20 Comments

Most of us are familiar with the concept of producing PCBs in a panel, and snapping them apart afterwards. V-grooves that go most of the way through a PCB are one way to go about this, but a line of perforations along which to snap a tab is another. But what’s the best size and spacing of holes to use? Sparkfun’s [Nick Poole] spent some $400 on PCBs to get some solid answers by snapping each of them apart, and judging the results.

The nice thing about creating a perforation line (or “mouse bites”) is that drill hits are a very normal thing in PCB production, which makes creating this kind of breakaway tab a very straightforward and flexible method. However, it can be tricky to get results that are just right. Too sturdy, and breaking apart is a hassle. Too weak, and the board may break or twist before its time. On top of that, edges must also break cleanly. We’ve covered panelizing PCBs in this way before, but this is the first time we’ve seen someone seriously look into how to create optimal breakaway tabs.

Placing holes tangent to the board edge (as shown above) isn’t the prettiest, but keeps PCB edges free from protrusions. This is best for boards that are rail-mounted, or have tight enclosures.

Data on designing mouse bites was sparse and a bit inconsistent, so [Nick] decided to figure it out empirically and share the results. The full details are available in Building a Better Mousebite (PDF download) but the essence of the recommendations are: 0.015″ unplated holes, spaced 0.025″ apart (center-to-center), tabs a maximum of 0.118″ wide (so as to be compatible with depanelizing tools), and holes that extend into the corners of the breakaway tab to avoid sharp edges. Holes should be placed slightly differently depending on whether one wishes to optimize the cosmetic appearance versus the physical smoothness of the board edge, but those numbers are the core of the guidelines.

To fine tune, [Nick] suggests increasing the spacing between holes to add strength, or just adding additional tabs. What about thickness of PCB? [Nick] tested boards both 0.8 mm and 1.6 mm thick, and while different amounts of torque were needed to snap the boards apart, things still worked as expected regardless of PCB thickness.

When it comes down to it, the best numbers will ultimately be the ones that your process or fab house can most efficiently handle, but [Nick]’s numbers should not steer anyone wrong, and it’s fantastic to see this kind of work go into refining such a common PCB feature.

Hacker Dictionary: RS-485 Will Go The Distance

April 5, 2022 by Arya Voronova 58 Comments

RS485 is a communication standard that should be part of the advanced hardware hacker’s arsenal; it’s not commonly encountered, but powerful exactly when you need it. It’s a physical layer interface for wired communications that uses a single differential pair for noise immunity, has good long-distance properties, and allows many connections to a single bus. Because of that, you will encounter it in security systems and even cameras, wired sensor networks, DMX512 lighting and all sorts of industrial electronics. For our hobbyist goals, you can absolutely use RS485 to build your home (or room) automation system, or a relatively large robot – without all those worries that wireless brings.

The name might remind you of RS232, and that’s because both RS232 and RS485 are standards that come from EIA (Electronics Industries Alliance). It also might remind you of RS422, if you’ve ever seen this name mentioned online – RS422 and RS485 are closely intertwined, sharing most of the physical layer, and I’ll show how exactly they relate. Continue reading “Hacker Dictionary: RS-485 Will Go The Distance” →

The BGA chip in question flipped onto a piecce of breadboard, all its pins broken out with magnet wire.

Heroic Efforts Give Smallest ARM MCU A Breakout, Open Debugger

March 21, 2022 by Arya Voronova 14 Comments

In today’s episode of Diminutive Device Technology Overview, [Sprite_TM] is at it again – this time conquering the HC32L110. A few weeks ago, we have highlighted the small ARM Cortex M0+ microcontroller, which is outstanding because of its exceptionally small size. We also pointed out a few hurdles, among them – hard-to-approach SDK and documentation, and difficulties making and assembling a PCB for such a small BGA. Today, we witness how [Sprite_TM] bulldozed through all of these hurdles for all of us, and added a few pictures to our collective “outrageous soldering” galleries while at it.

First, he figured out an example layout for this MCU that’s achievable for us even on a cheapest 2-layer board from JLCPCB, keeping distances within the generic tolerance standards by snubbing out a few pins. As a result, we only lose access to four GPIOs – those will have to be kept as inputs, so that nothing burns out. However, that’s the kind of tradeoff we are okay making if it helps us keep our PCB small and lightweight for projects where these factors matter. After receiving the resulting board, he also recorded a short tutorial on soldering such packages at home with a mere hot air gun and a few bare necessities like flux and tweezers – embedded below.

It doesn’t end there, however, as he decided to work around the GPIO fanout limitation in a non-intended way. Evidently, [Sprite_TM] decided to have some fun, taking a piece of regular 0.1″ spacing protoboard and deadbugging the chip with magnet wire, much to our amusement. The resulting contraption, pictured above, worked – and this is ever something you’d like to be able to achieve yourself in times of dire need, whether you make something work or simply to be entertained by making use of a cursed mounting technique, there’s an one-hour-long livestream recording of how this magnet wire contraption came to be. And, of course, that wasn’t the last thing to be shared.

Continue reading “Heroic Efforts Give Smallest ARM MCU A Breakout, Open Debugger” →

An assortment of MemoryStick cards and devices, some of them, arguably cursed, like a MemoryStick-slot-connected camera.

Hacker Challenges MemoryStick To A Fight And Wins

March 20, 2022 by Arya Voronova 24 Comments

It’s amazing when a skilled hacker reverse-engineers a proprietary format and shares the nitty-gritty with everyone. Today is a day when we get one such write-up – about MemoryStick. It is one of those proprietary formats, a staple of Sony equipment, these SD-card-like storage devices were evidently designed to help pad Sony’s pockets, as we can see from the tight lock-in and inflated prices. As such, this format has always remained unapproachable to hackers. No more – [Dmitry Grinberg] is here with an extensive breakdown of MemoryStick protocol and internals.

If you ever want to read about a protocol that is not exactly sanely designed, from physical layer quirks to things like inexplicable large differences between MemoryStick and MemoryStick Pro, this will be an entertaining read for hackers of all calibers. Dmitry doesn’t just describe the bad parts of the design, however, as much as that rant is entertaining to read – most of the page is taken by register summaries, struct descriptions and insights, the substance about MemoryStick that we never got.

One sentence is taken to link to a related side project of [Dmitry] that’s a rabbithole on its own – he has binary patched MemoryStick drivers for PalmOS to add MemoryStick Pro support to some of the Sony Clie handhelds. Given the aforementioned differences between non-Pro and Pro standards, it’s a monumental undertaking for a device older than some of this site’s readers, and we can’t help but be impressed.

To finish the write-up off, [Dmitry] shares with us some MemoryStick bit-banging examples for the STM32. Anyone who ever wanted to approach MemoryStick, be it for making converter adapters to revive old tech, data recovery or preservation purposes, or simply hacker curiosity, now can feel a bit less alone in their efforts.

We are glad to see such great hacking on the MemoryStick front – it’s much needed, to the point where our only article mentioning MemoryStick is about avoiding use of the MemoryStick slot altogether. [Dmitry] is just the right person for reverse-engineering jobs like this, with extensive reverse-engineering history we’ve been keeping track of – his recent reverse-engineering journey of an unknown microcontroller in cheap E-Ink devices is to behold.