Embedded Python: MicroPython Is Amazing

July 11, 2024 by 105 Comments

In case you haven’t heard, about a month ago MicroPython has celebrated its 11th birthday. I was lucky that I was able to start hacking with it soon after pyboards have shipped – the first tech talk I remember giving was about MicroPython, and that talk was how I got into the hackerspace I subsequently spent years in. Since then, MicroPython been a staple in my projects, workshops, and hacking forays.

If you’re friends with Python or you’re willing to learn, you might just enjoy it a lot too. What’s more, MicroPython is an invaluable addition to a hacker’s toolkit, and I’d like to show you why. Continue reading “Embedded Python: MicroPython Is Amazing” →

Building A Cassette Deck Controller To Save A Locked Out Car Stereo

July 9, 2024 by 27 Comments

Cars have had DRM-like measures for longer than you might think. Go back to the 1990s, and coded cassette decks were a common way to stop thieves being able to use stolen stereos. Sadly, they became useless if you ever lost the code. [Simon] had found a deck in great condition that was locked out, so he set about building his own controller for it. 

The build relies on the cassette transport of a car stereo and a VFD display, but everything else was laced together by Simon. It’s a play-only setup, with no record, seeing as its based on an automotive unit. [Simon]’s write up explains how he reverse engineered the transport, figuring out how the motors and position sensors worked to control the playback of a cassette.

[Simon] used an Atmega microcontroller as the brains of the operation, which reads the buttons of the original deck via an ADC pin to save I/O for other tasks. The chip also drives the VFD display for user feedback, and handles auto reverse too. The latter is thanks to the transport’s inbuilt light barriers, which detect the tape’s current status. On the audio side, [Simon] whipped up his own head amplifier to process the signal from the tape head itself.

Fundamentally, it’s a basic build, but it does work. We’ve seen other DIY tape decks before, too. There’s something about this format that simply refuses to die. The fans just won’t let Compact Cassette go down without a fight. Video after the break.

Continue reading “Building A Cassette Deck Controller To Save A Locked Out Car Stereo” →

Lithium-Ion Batteries Power Your Devboards Easily

March 14, 2024 by 25 Comments

Last summer, I was hanging out with a friend from Netherlands for a week, and in the middle of that week, we decided to go on a 20 km bike trip to a nearby beach. Problem? We wanted to chat throughout the trip, but the wind noise was loud, and screaming at each other while cycling wouldn’t have been fun. I had some walkie-talkie software in mind, but only a single battery-powered Pi in my possession. So, I went into my workshop room, and half an hour later, walked out with a Pi Zero wrapped in a few cables.

I wish I could tell you that it worked out wonders. The Zero didn’t have enough CPU power, I only had single-core ones spare, and the software I had in mind would start to badly stutter every time we tried to run it in bidirectional mode. But the battery power solution was fantastic. If you need your hack to go mobile, read on.

Continue reading “Lithium-Ion Batteries Power Your Devboards Easily” →

Teardown: Cobra XRS 9740 Radar Detector

March 18, 2020 by 46 Comments

Drivers with a lead foot more often than not have Waze open on their phone so they can see if other drivers have spotted cops up ahead. But avoiding a speeding ticket used to involve a lot more hardware than software. Back before the smartphone revolution, that same driver would have had a radar detector on their dashboard. That’s not to say the gadgets are completely unused today, but between their relatively high cost (one of the top rated models on Amazon as of this writing costs over $300) and the inevitable false positives from so many vehicles on the road having their own radar and LIDAR systems, they’ve certainly become a less common sight over the years

The subject of today’s teardown is a perfect example of “Peak Radar Detector”. Manufactured back in 2007, the Cobra XRS 9740 would have been a fairly mid-range entry offering the sort of features that would have been desirable at the time. Over a decade ago, having an alphanumeric display, voice alerts, and a digital compass were all things worth shouting about on the box the thing was sold in. Though looking like some kind of Cardassian warship was apparently just an added bonus.

As the name implies these devices are primarily for detecting radar activity, but by this point they’d also been expanded to pick up infrared lasers and the strobe beacons on emergency vehicles. But false positives were always a problem, so the device allows the user to select which signals it should be on the lookout for. If you were getting some kind of interference that convinced the detector it was being bombarded with IR lasers, you could just turn that function off without having to pull the plug entirely.

But it’s important to remember that this device was built back when people were still unironically carrying around flip phones. Detecting laser and multi-band radars might sound like something pulled from the spec sheet of a stealth fighter jet, but this is still a piece of consumer electronics from more than a decade in the past. So let’s crack it open and take a look at what goes on inside a radar detector that’s only a few years away from being old enough to get its own driver’s license.

Continue reading “Teardown: Cobra XRS 9740 Radar Detector” →

Badge builder's meetup at DC27

Pictorial Guide To The Unofficial Electronic Badges Of DEF CON 27

September 19, 2019 by 15 Comments

DEF CON has become the de facto showplace of the #Badgelife movement. It’s a pageant for clever tricks that transform traditional green rectangular circuit boards into something beautiful, unique, and often times hacky.

Today I’ve gathered up about three dozen badge designs seen at DC27. It’s a hint of what you’ll see in the hallways and meetups of the conference. From hot-glue light pipes and smartphone terminal debugging consoles to block printing effects and time of flight sensors, this is a great place to get inspiration if you’re thinking of trying your hand at unofficial badge design.

If you didn’t catch “The Badgies” you’ll want to go back and read that article too as it rounds up the designs I found to be the craziest and most interesting including the Car Hacking Village, Space Force, SecKC, DC503, and Frankenbadge. Do swing by the Hands-On articles for the AND!XOR badge and for [Joe Grand’s] official DC27 badge. There was also a lot of non-badge hardware on display during Hackaday’s Breakfast at DEF CON so check out that article as well.

Enough preamble, let’s get to the badges!

Continue reading “Pictorial Guide To The Unofficial Electronic Badges Of DEF CON 27” →

Core Rope Memory Makes One Of The Oddest LED Flashers We’ve Ever Seen

September 10, 2019 by 5 Comments

If you’ve heard of core rope memory, it will probably be in the context of vintage computing equipment such as Apollo-era NASA hardware. A string of magnetic cores and sense wires form a simple ROM arrangement, which though long-ago-superceded by semiconductor memory remains possible to recreate by the experimenter. It’s a path [Nicola Cimmino] has trodden, as he’s not only made a few nibbles of core rope memory, but incorporated it with an Arduino as part of one of the most unusual LED flashers we’ve ever seen. The memory holds a known sequence of bits which is retrieved in sequence by the Arduino, and the LED is kept flashing as long as the read values conform to those expected.

The memory itself is simple enough (and not to be confused with magnetic core memory). The cores are ferrite rings that form a sequence of small transformers that become the bits of the memory. Individual bits are set high or low by either passing a sense wire through a core to create a primary, or bypassing it. Multiple sense wires can be used for separate nibbles in the same cores, so for example his four nibbles all share the same four cores. Pulses are sent down the wires, either passing through a core or not, and equivalently picked up or not on sense lines.

In this case the sense wire is driven directly to ground by Arduino pins which means that the circuit is relying upon the current limiting of the ATmega328 to avoid destroying itself, it’s possible we’d add a driver transistor. The bits are read meanwhile from the secondary windings through a diode rectifier and capacitor to an Arduino analogue pin.

Core memory has been paired with an Arduino before on these pages, though of the RAM variety.

The Not Quite USB-C Of Nintendo Switch Accessories

August 4, 2019 by 10 Comments

Historically gaming consoles are sold at little-to-no profit in order to entice customers with a low up-front price. The real profits roll in afterwards from sales of games and accessories. Seeking a slice of the latter, aftermarket accessory makers jump in with reverse-engineered compatible products at varying levels of “compatible”.

When the Nintendo Switch was released with a standard USB-C port for accessories, we had hoped those days of hit-or-miss reverse engineering were over, but reality fell short. Redditor [VECTORDRIVER] summarized a few parts of this story where Nintendo deviated from spec, and accessory makers still got things wrong.

Officially, Nintendo declared the Switch USB-C compliant. But as we’ve recently covered, USB-C is a big and complicated beast. Determined to find the root of their issues, confused consumers banded together on the internet to gather anecdotal evidence and speculate. One theory is that Nintendo’s official dock deviated from official USB-C dimensions in pursuit of a specific tactile feel; namely reducing tolerance on proper USB-C pin alignment and compensating with an internal mechanism. With Nintendo playing fast and loose with the specs, it makes developing properly functioning aftermarket accessories all the more difficult.

But that’s not the only way a company can slip up with their aftermarket dock. A teardown revealed Nyko didn’t use a dedicated chip to manage USB power delivery, choosing instead to implement it in software running on ATmega8. We can speculate on why (parts cost? time to market?) but more importantly we can read the actual voltage on its output pins which are too high. Every use becomes a risky game of “will this Switch tolerate above-spec voltage today?” We expect that as USB-C becomes more common, it would soon be cheapest and easiest to use a dedicated chip, eliminating the work of an independent implementation and risk of doing it wrong.

These are fairly typical early teething problems for a new complex technology on their road to ubiquity. Early USB keyboard and mice didn’t always work, and certain combination of early PCI-Express cards and motherboards caused damage. Hopefully USB-C problems — and memories of them — will fade in time as well.

[via Ars Technica]

[Main image source: iFixit Nintendo Switch Teardown]