Month: July 2024

Smartwatch Snitches On Itself And Enables Reverse Engineering

July 4, 2024 by 10 Comments

If something has a “smart” in its name, you know that it’s talking to someone else, and the topic of conversation is probably you. You may or may not like that, but that’s part of the deal when you buy these things. But with some smarts of your own, you might be able to make that widget talk to you rather than about you.

Such an opportunity presented itself to [Benjamen Lim] when a bunch of brand X smartwatches came his way. Without any documentation to guide him, [Benjamen] started with an inspection, which revealed a screen of debug info that included a mysterious IP address and port. Tearing one of the watches apart — a significant advantage to having multiple units to work with — revealed little other than an nRF52832 microcontroller along with WiFi and cellular chips. But the luckiest find was JTAG pins connected to pads on the watch face that mate with its charging cradle. That meant talking to the chip was only a spliced USB cable away.

Once he could connect to the watch, [Benjamen] was able to dump the firmware and fire up Ghidra. He decided to focus on the IP address the watch seemed fixated on, reasoning that it might be the address of an update server, and that patching the firmware with a different address could be handy. He couldn’t find the IP as a string in the firmware, but he did manage to find a sprintf-like format string for IP addresses, which led him to a likely memory location. Sure enough, the IP and port were right there, so he wrote a script to change the address to a server he had the keys for and flashed the watch.

So the score stands at [Benjamen] 1, smartwatch 0. It’s not clear what the goal of all this was, but we’d love to see if he comes up with something cool for these widgets. Even if there’s nothing else, it was a cool lesson in reverse engineering.

The Workstation You Wanted In 1990, In Your Pocket

July 3, 2024 by 61 Comments

Years ago there was a sharp divide in desktop computing between the mundane PC-type machines, and the so-called workstations which were the UNIX powerhouses of the day. A lot of familiar names produced these high-end systems, including the king of the minicomputer world, DEC. The late-80s version of their DECstation line had a MIPS processor, and ran ULTRIX and DECWindows, their versions of UNIX and X respectively. When we used one back in the day it was a very high-end machine, but now as [rscott2049] shows us, it can be emulated on an RP2040 microcontroller.

On the business card sized board is an RP2040, 32 MB of PSRAM, an Ethernet interface, and a VGA socket. The keyboard and mouse are USB. It drives a monochrome screen at 1024 x 864 pixels, which would have been quite something over three decades ago.

It’s difficult to communicate how powerful a machine like this felt back in the very early 1990s, when by today’s standards it seems laughably low-spec. It’s worth remembering though that the software of the day was much less demanding and lacking in bloat. We’d be interested to see whether this could be used as an X server to display a more up-to-date application on another machine, for at least an illusion of a modern web browser loading Hackaday on DECWindows.

Full details of the project can be found in its GitHub repository.

A Trip Down Electronic Toy Memory Lane

July 3, 2024 by 46 Comments

Like many of us, [MIKROWAVE1] had a lot of electronic toys growing up. In a video you can watch below, he asks the question: “Did electronic toys influence your path?” Certainly, for us, the answer was yes.

The CB “base station” looked familiar although ours was marked “General Electric.” Some of us certainly had things similar to the 150-in-one kit and versions of the REMCO broadcast system. There were many versions of crystal radio kits, although a kit for that always seemed a little like cheating.

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VHF/UHF Antennas, The Bad, The Ugly, And The Even Worse

July 3, 2024 by 69 Comments

When you buy a cheap ham radio handy-talkie, you usually get a little “rubber ducky” antenna with it. You can also buy many replacement ones that are at least longer. But how good are they? [Learnelectronics] wanted to know, too, so he broke out his NanoVNA and found out that they were all bad, although some were worse than others. You can see the results in the — sometimes fuzzy — video below.

Of course, bad is in the eye of the beholder and you probably suspected that most of them weren’t super great, but they do seem especially bad. So much so, that, at first, he suspected he was doing something wrong. The SWR was high all across the bands the antennas targeted.

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Responsive LCD Backlights With A Little Lateral Thinking

July 3, 2024 by 23 Comments

LCD televisions are a technological miracle, but if they have an annoying side it’s that some of them are a bit lacklustre when it comes to displaying black. [Mousa] has a solution, involving a small LCD and a bit of lateral thinking.

These screens work by the LCD panel being placed in front of a bright backlight, and only letting light through at bright parts of the picture. Since LCD isn’t a perfect attenuator, some of the light can make its way through, resulting in those less than perfect blacks. More recent screens replace the bright white backlight with an array of LEDs that light up with the image, but the electronics to make that happen are not exactly trivial.

The solution? Find a small LCD panel and feed it from the same HDMI source as a big panel. Then place an array of LDRs on the front of the small LCD, driving an array of white LEDs through transistor drivers to make a new responsive backlight. We’re not sure we’d go to all this trouble, but it certainly looks quite cool as you can see below the break.

This may be the first responsive backlight we’ve brought you, but more than one Ambilight clone has graced these pages.

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FLOSS Weekly Episode 790: Better Bash Scripting With Amber

July 3, 2024 by 8 Comments

This week Jonathan Bennett and Dan Lynch chat with Paweł Karaś about Amber, a modern scripting language that compiles into a Bash script. Want to write scripts with built-in error handling, or prefer strongly typed languages? Amber may be for you!

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USB And The Myth Of 500 Milliamps

July 3, 2024 by 91 Comments

If you’re designing a universal port, you will be expected to provide power. This was a lesson learned in the times of LPT and COM ports, where factory-made peripherals and DIY boards alike had to pull peculiar tricks to get a few milliamps, often tapping data lines. Do it wrong, and a port will burn up – in the best case, it’ll be your port, in worst case, ports of a number of your customers.

Want a single-cable device on a COM port? You might end up doing something like this.

Having a dedicated power rail on your connector simply solves this problem. We might’ve never gotten DB-11 and DB-27, but we did eventually get USB, with one of its four pins dedicated to a 5 V power rail. I vividly remember seeing my first USB port, on the side of a Thinkpad 390E that my dad bought in 2000s – I was eight years old at the time. It was merely USB 1.0, and yet, while I never got to properly make use of that port, it definitely marked the beginning of my USB adventures.

About six years later, I was sitting at my desk, trying to build a USB docking station for my EEE PC, as I was hoping, with tons of peripherals inside. Shorting out the USB port due to faulty connections or too many devices connected at once was a regular occurrence; thankfully, the laptop persevered as much as I did. Trying to do some research, one thing I kept stumbling upon was the 500 mA limit. That didn’t really help, since none of the devices I used even attempted to indicate their power consumption on the package – you would get a USB hub saying “100 mA” or a mouse saying “500 mA” with nary an elaboration.

Fifteen more years have passed, and I am here, having gone through hundreds of laptop schematics, investigated and learned from design decisions, harvested laptops for both parts and even ICs on their motherboards, designed and built laptop mods, nowadays I’m even designing my own laptop motherboards! If you ever read about the 500 mA limit and thought of it as a constraint for your project, worry not – it’s not as cut and dried as the specification might have you believe.
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