serial port

37 Articles

A CaptionCall Phone Succumbs To Doom, Again

March 2, 2025 by 11 Comments

Pour one out for yet another device conquered. This one’s a desk phone for conferences and whatnot, a colour display, a numpad, and a bog standard handset with a speaker and mic. Naturally, also running Linux. You know what to expect – [Parker Reed] has brought Doom to it, and you’d be surprised how playable it looks!

This is the second time a CaptionCall device has graced our pages running Doom — CaptionCall patched out the previous route, but with some firmware dumping and hashcat, root has been acquired once again. [Parker] has upgraded this impromptu gaming setup, too – now, all the buttons are mapped into Doom-compatible keyboard events coming from a single input device, thanks to a C program and an Xorg config snippet. Feel free to yoink for your own Doom adventures or just general CaptionCall hacking!

If you’re interested in the hacking journey, get into the exploitee.rs Discord server and follow the hack timeline from password recovery, start to finish, to Doom, to the state of affairs shown in the video. Now, as the CPU speeds have risen, should the hackerdom switch away from Doom as the go-to? Our community remains divided.

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Grab Your ‘Scope’s Screen From The Command Line

July 25, 2023 by 9 Comments

Many of us have oscilloscopes and other instruments with built-in digital interfaces, but how many of us use them? [Andrej Radović] has a Tektronix TDS2022 which can print its screen to any of its various interfaces, and he set about automating the process of acquisition with a Bash script.

The easiest interface to use was the trusty serial port — hardly the fastest but definitely the best supported. But how does one retrieve an image fired down a serial port? Most of the post is devoted to spotting file headers in a Bash script monitoring the serial port, and streaming the result to a local file. There’s a discussion of the various formats supported by the Tek, with an ancient PCX bitmap format being chosen over Postscript for speed. The result is a decent quality screen grab, making the ‘scope that little bit more useful and perhaps extending its life.

Perhaps your instrument isn’t a TEK, but the chances are you can still make it bend to your will from a PC. Try it, with the magic of VISA.

IR Camera Is Excellent Hacking Platform

June 1, 2023 by 14 Comments

While there have been hiccups here and there, the general trend of electronics is to decrease in cost or increase in performance. This can be seen in fairly obvious ways like more powerful and affordable computers but it also often means that more powerful software can be used in other devices without needing expensive hardware to support it. [Manawyrm] and [Toble_Miner] found this was true of a particular inexpensive thermal camera that ships with Linux installed on it, and found that this platform was nearly perfect for tinkering with and adding plenty of other features to turn it into a much more capable tool.

The duo have been working on a SC240N variant of the InfiRay C200 infrared camera, which ships with a Hisilicon SoC. The display is capable of displaying 25 frames per second, making this platform an excellent candidate for modifying. A few ports were added to the device, including USB and MicroSD, and which also allows the internal serial port to be accessed easily. From there the device can be equipped with the uboot bootloader in order to run essentially anything that could be found on any other Linux machine such as supporting a webcam interface (and including a port of DOOM, of course). The duo doesn’t stop at software modifications though. They also equipped the camera with a lens, attached magnetically, which changes the camera’s focal length to give it improved imaging capabilities at closer ranges.

While the internal machinations of this device are interesting, it actually turns out to be a fairly capable infrared camera on its own as well. The hardware and software requirements for these devices certainly don’t need a full Linux environment to work, and while we have seen thermal cameras that easily fit in a pocket that are based on nothing any more powerful than an ESP32, it does tend to simplify the development process dramatically to include Linux and a little more processing power if you can.

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A small brown PCB with various components on it. There is a headphone cable and DC barrel connector cable coming out of it.

Put Your Serial Port On The Web

January 7, 2023 by 37 Comments

Today, everything from your computer to your dryer has wireless communications built in, but devices weren’t always so unencumbered by wires. What to do when you have a legacy serial device, but no serial port on the computer you want to connect? [vahidyou] designed a wireless serial dongle to solve this conundrum.

Faced with a CNC that took instructions over serial port, and not wanting to deal with the cabling involved in a serial to USB adapter, [vahidyou] turned to an ESP8266 to let his computer and device talk wirelessly. The hand-made PCB connects via a 3.5 mm headphone jack to DB9 adapter which he describes in another article. While [vahidyou] did write a small Windows program for managing the device, it is probably easier to simply access it in a web browser from any device you have handy.

Want to see another wireless serial port application? This Palm Portable Keyboard Bluetooth dongle will let you type in comfort on the go, or you can use a PiModem to get your retrocomputer online!

Linux Fu: Eavesdropping On Serial

September 7, 2022 by 21 Comments

In the old days, if you wanted to snoop on a piece of serial gear, you probably had a serial monitor or, perhaps, an attachment for your scope or logic analyzer. Today, you can get cheap logic analyzers that can do the job, but what if you want a software-only solution? Recently, I needed to do a little debugging on a USB serial port and, of course, there isn’t really anywhere to easily tie in a monitor or a logic analyzer. So I started looking for an alternate solution.

If you recall, in a previous Linux Fu we talked about pseudoterminals which look like serial ports but actually talk to a piece of software. That might make you think: why not put a piece of monitor software between the serial port and a pty? Why not, indeed? That’s such a good idea that it has already been done. When it works, it works well. The only issue is, of course, that it doesn’t always work.

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Photo of the head unit , with "Hacked by greenluigi1" in the center of the UI

Hacker Liberates Hyundai Head Unit, Writes Custom Apps

July 18, 2022 by 39 Comments

[greenluigi1] bought a Hyundai Ioniq car, and then, to our astonishment, absolutely demolished the Linux-based head unit firmware. By that, we mean that he bypassed all of the firmware update authentication mechanisms, reverse-engineered the firmware updates, and created subversive update files that gave him a root shell on his own unit. Then, he reverse-engineered the app framework running the dash and created his own app. Not just for show – after hooking into the APIs available to the dash and accessible through header files, he was able to monitor car state from his app, and even lock/unlock doors. In the end, the dash got completely conquered – and he even wrote a tutorial showing how anyone can compile their own apps for the Hyundai Ionic D-Audio 2V dash.

In this series of write-ups [greenluigi1] put together for us, he walks us through the entire hacking process — and they’re a real treat to read. He covers a wide variety of things: breaking encryption of .zip files, reprogramming efused MAC addresses on USB-Ethernet dongles, locating keys for encrypted firmware files, carefully placing backdoors into a Linux system, fighting cryptic C++ compilation errors and flag combinations while cross-compiling the software for the head unit, making plugins for proprietary undocumented frameworks; and many other reverse-engineering aspects that we will encounter when domesticating consumer hardware.

This marks a hacker’s victory over yet another computer in our life that we aren’t meant to modify, and a meticulously documented victory at that — helping each one of us fight back against “unmodifiable” gadgets like these. After reading these tutorials, you’ll leave with a good few new techniques under your belt. We’ve covered head units hacks like these before, for instance, for Subaru and Nissan, and each time it was a journey to behold.

Tio Is A Serial Terminal For Us

July 13, 2022 by 31 Comments

With Linux and the serial port there is good news and there is bad news. The good news is that Linux has great support for serial hardware of all sorts and a host of tools for accessing the serial port. That’s important when you use a lot of serial-like devices like Arduinos with USB ports and the like. The bad news is that most of the terminal software is made to accommodate the days when a computer had real serial terminals and modems with people interacting with them. We bet that’s why [lundmar] developed tio, a serial device I/O tool for people like us.

Honestly, how many times have you needed Zmodem file transfers and recognition of the DCD signal to detect an incoming connection? Sure there are many other programs that will do the job, but tio brings a clean simplicity along with functionality that embedded developers need.

The software will support arbitrary devices, show statistics, and give you control of the RS232 lines. There’s support for delayed characters and lines, useful if you are dealing with a super simple device with no handshaking. There’s also hex support and many ways to log data and statistics. We especially like that it can automatically reconnect which is a great feature.

Of course, you want some terminal features and tio includes those. For example, you can elect to have local echo turned on or map characters so that, for example, a carriage return turns into a carriage return and a line feed. You can use command line options to set up most items including features like redirecting to a network socket. Other commands inside the program — by default, triggered by Control+T — let you do things like send a break, toggle handshaking lines, and more.

You might think the serial port is dead, but it really just transformed into a USB port.  Of course, like everything else these days, you can also get your terminal in the browser.