Sometimes reverse engineering embedded systems can be a right old faff, with you needing to resort to all kinds of tricks such as power glitching in order to poke a tiny hole in the armour, giving you an way in. And, sometimes the door is just plain wide open. This detailed exploration of an off-the-shelf retro arcade machine, is definitely in that second camp, for an unknown reason. [Matthew Alt] of VoidStar Security, took a detailed look into how this unit works, which reads as a great introduction to how embedded Linux is constructed on these minimal systems.
The hardware is the usual bartop cabinet, with dual controls and an LCD display, with just enough inside a metal enclosure to drive the show. Inside this, the main PCB has the expected minimal ARM-based application processor with its supporting circuit. The processor is the Rockchip RK3128, sporting a quad-core ARM Neon and a Mali400 GPU, but the main selling point is the excellent Linux support. You’ll likely see this chip or its relatives powering cheap Android TV boxes, and it’s the core of this nice looking ‘mini PC’ platform from firefly. Maybe something to consider seeing as though Raspberry Pis are currently so hard to come by?
Anyway, we digress a little, [Matthew] breaks it down for us in a very methodical way, first by identifying the main ICs and downloading the appropriate datasheets. Next he moves on to connectors, locating an internal non-user-facing USB micro port, which is definitely going to be of interest. Finally, the rather obvious un-populated 3-pin header is clearly identified as a serial port. This was captured using a Saleae clone, to verify it indeed was a UART interface and measure the baud rate. After doing that, he hooked it into a Raspberry Pi UART and by attaching the standard screen utility to the serial device, lo-and-behold, a boot log and a root prompt! This thing really is barn-door wide-open.
Simply by plugging in a USB stick, the entire flash memory was copied over, partitions and all, giving a full backup in case subsequent hacking messed things up. Being based on U-Boot, it was a trivial matter of just keying in ‘Ctrl-C’ at boot time, and he was dropped straight into the U-Boot command line, and all configuration could be easily read out. By using U-Boot to low-level dump the SPI flash to an external USB device, via a RAM copy, he proved he could do the reverse and write the same image back to flash without breaking something, so it was now possible to reverse engineer the software, make changes and write it back. Automation of the process was done using Depthcharge on the Raspberry Pi, which was also good to read about. We will keep an eye on the blog for what he does with it next!
If there’s one thing we know about Imperial Stormtroopers in Star Wars, it’s that they’re not very good at their jobs. Perhaps they’d be better at holding up your books instead of defending the Empire. This pair of resin bookends features a duo of white-clad soldiers doing their best to keep your books from falling over.
How do you look back over your life and divide it up? Maybe by decades, cultural moments, or geopolitical events. For radio amateurs with older callsigns there’s a temptation to do so by solar cycles, as the roughly 11-year period of the Sun’s activity had a huge effect on radio propagation through the charge it creates in the upper atmosphere. We’re now in solar cycle 25, numbered since the 18th century when the science of solar observation began, and as never before we’re surrounded by information from experts such as [Dr. Tamitha Skov], the so-called [Space Weather Woman]. When she says something is on the way we listen, so a recent Tweet predicting a direct hit from a solar storm with a good probability of auroras in lower latitudes is very much worth sharing.
We must extend our commiserations to readers in equatorial climes and ever through the lower half of the USA, southern Europe, the Middle East, India, Japan, and China. You won’t see the aurora we’ll catch in Europe along with our friends in New Zealand, Canada, Russia, and northern USA. But even then to those of us at moderate latitudes an aurora is a pretty rare event, so we’re hoping for clear skies on the 2nd of February and would advise you to look out too if you’re in the likely zone even if they won’t be quite as impressive as those in our header picture. Meanwhile radio amateurs everywhere don’t have to see pretty lights in the sky to reap the benefits in terms of propagation, so happy DX hunting! The Tweet is embedded below the break, so you can play the timeline for yourselves.
Direct Hit! NASA, NOAA & MetOffice predictions agree the #solarstorm launched Jan 29 will hit Earth by early Feb 2! This one is slow so expect #aurora only as far south as Netherlands, north USA, & up to north New Zealand & Tasmania. #GPS & HF #radio issues on Earth’s nightside! pic.twitter.com/Uua1LGMgJR
Made in Germany, these 4″ long slip-joint pliers Knipex are small enough to carry in your pants pocket but strong enough for serious work in the field. They offer one-handed adjustment and lock firmly onto pipes, nuts, and other objects you need to grab up to 1″ in diameter. For bigger jobs, they come in sizes from 5″ to 22″.
A more compact version of Cloudnola’s flip clock. Like the TextTime, it tells time using words instead of numbers. The battery-operated clock can sit on a tabletop or be wall-mounted. It’s available in white-on-black or black-on-white with a red base. Made from metal with PVC flip panels.
The Raspberry Pi single board computers (SBCs for short) are normally used with the Raspberry Pi OS. This is great for gaming and web browsing, but isn’t designed for microcontroller-like tasks. Tasks like reading I2C sensors and SPI devices can be trickier. Furthermore, Linux system maintenance can be tricky for beginners.
Instead of Raspberry Pi OS, one can now use CircuitPython instead. CircuitPython running without another operating system (OS) is typically known as “bare metal”. This greatly simplifies system maintenance and makes it easier to treat the Raspberry Pi like a microcontroller. In addition, running CircuitPython on the Raspberry Pi increases the amount of flash and RAM available to CircuitPython programs. Finally, it also adds the ability to use displayio on HDMI displays.
Wearing a mask is one of the most important things we can do during the pandemic. But we never really thought about how that might impact those who rely on lip reading. Programmer Kevin Lewis came up with a solution that uses Deepgram AI to transcribe speech in real-time and display it on a wearable screen.
Masks making it hard to understand people either audibly or because you rely on lip reading? Just got this hacked together – it displays my speech in real time with @DeepgramAI! pic.twitter.com/lPu4CZboIk