Author: Arya Voronova

490 Articles

The line injector shown characterising the PSRR of an AMS1117 regulator, with a bunch of stuff connected to it through SMA jacks

A Simple Line Injector Shows You The Wonderful World Of PSRR

April 5, 2024 by 8 Comments

[limpkin] writes us to show a line injector they’ve designed. The principle is simple — if you want to measure how much PSU noise any of your electronic devices let through, known as PSRR (Power Supply Rejection Ratio), you can induce PSU noise with this board, and then measure noise on your device’s output. The board is likewise simple. A few connectors, resistors, and caps, and a single N-FET!

You do need a VNA, but once you have that, you get a chance to peek into an entire world of insights. Does that 1117 LDO actually filter out noise better than a buck regulator? Is it enough to use a Pi filter for that STM32’s ADC rail, and do the actual parts you’re using actually help with that task? How much noise does your device actually let through in the real world, after being assembled with the specific components you’ve picked? [limpkin] shows us a whole bunch of examples – putting regulators, filters and amplifiers to the test, and showing us how there’s more than meets the eye.

Everything is open source, with full files available on the blog. And, if you want it pre-assembled, tested and equipped with the CNC-milled case, you can get it on Tindie or Lektronz! Of course, even without a tool like this, you can still get good filter designs done with help of computer-aided modelling.

We thank [alfonso] for sharing this with us!

The I2C extender board on a white background, fully assembled, with two connectors and two indicator LEDs

Extenders And Translators For Your I2C Toolkit

April 5, 2024 by 5 Comments

If you’ve ever been laying out a network I2C devices inside a project box or throughout your robot’s body, you’ll probably know that I2C is not without its pitfalls. But for many of those pitfalls, there’s a handy chip you can use. [Roman Dvořák] from ThunderFly has experienced it on their drone building journeys, and that’s why they bring us two wonderful open source hardware boards: an I2C bus extender, and an I2C address translator.

The first board, an I2C bus extender, is based around the TCA4307 chip, and not only it lets you extend the bus further than it would normally go, it would also protect you. When the bus capacity is no longer handleable by your devices, or a particular misbehaving device gets the bus stuck, this chip will take care of it and dissipate your troubles. It will even let you know when your bus is wired up correctly, with a handy shine-through LED!

The second board is an I2C address translator. We’ve covered them before, but in short, address translators let you avoid I2C address conflicts while using multiple devices that share the same address. This particular module uses the LTC4317 chip, a common choice for such translation, and the board leaves no feature unimplemented. In the README, there’s quite a few pictures with examples of where this sensor proves mighty useful, too!

It appears that ThunderFly open sources a lot of their designs on GitHub, an effort that we salute. The designs are great to learn from, but if you’re just looking for turn-key hardware, you can get both of these boards from their Tindie store. The cables they use have locking connectors, but as long as the pinout matches, you should be able to solder a JST-SH socket and add these modules to your QWIIC toolkit.

The assembled PCB on red foam, with both a USB-C connector and the ASM2464PD chip visible

Finally Taming Thunderbolt With Third-Party Chips

April 4, 2024 by 16 Comments

Thunderbolt has always been a functionally proprietary technology, held secret by Intel until “opening” the standard in a way that evidently wasn’t enough for anyone to meaningfully join in. At least, until last year, when we saw announcements about ASMedia developing two chips for Thunderbolt use. Now, we are starting to see glimmers of open source, letting us tinker with PCIe at prices lower than $100 per endpoint.

In particular, this board from [Picomicro] uses the ASM2464PD — a chipset that supports TB3/4/USB4, and gives you a 4x PCIe link. Harnessing the 40 Gbps power to wire up an NVMe SSD, this board shows us it’s very much possible to design a fully functional ASM2464PD board without the blessing of Intel. With minimal footprint that barely extends beyond the 2230 SSD it’s designed for, curved trace layout, and a CNC-milled case, this board sets a high standard for a DIY Thunderbolt implementation.

The main problem is that this project is not open-source – all we get is pretty pictures and a bit of technical info. Thankfully, we’ve also seen [WifiCable] take up the mantle of making this chip actually hobbyist-available – she’s created a symbol, fit a footprint, and made an example board in KiCad retracing [Picomicro]’s steps in a friendly fashion. The board is currently incomplete because it needs someone to buy an ASM2464PD enclosure on Aliexpress and reverse-engineer the missing circuitry, but if open-source Thunderbolt devices are on your wish list, this is as close as you get today – maybe you’ll be able to make an eGPU adapter, even. In the meantime, if you don’t want to develop hardware but want to take advantage of Thunderbolt, you can build 10 Gbps point-to-point networks.

USB HID And Run Exposes Yet Another BadUSB Surface

April 4, 2024 by 20 Comments

You might think you understand the concept of BadUSB attacks and know how to defend it, because all you’ve seen is opening a terminal window. Turns out there’s still more attack surface to cover, as [piraija] tells us in their USB-HID-and-run publication. If your system doesn’t do scrupulous HID device filtering, you might just be vulnerable to a kind of BadUSB attack you haven’t seen yet, rumoured to have been the pathway a few ATMs got hacked – simply closing the usual BadUSB routes won’t do.

The culprit is the Consumer Control specification – an obscure part of HID standard that defines media buttons, specifically, the “launch browser” and “open calculator” kinds of buttons you see on some keyboards, that operating systems, surprisingly, tend to support. If the underlying OS you’re using for kiosk purposes isn’t configured to ignore these buttons, they provide any attacker with unexpected pathways to bypass your kiosk environment, and it works astonishingly well.

[piraija] tells us that this attack provides us with plenty of opportunities, having tested it on a number of devices in the wild. For your own tests, the writeup has Arduino example code you can upload onto any USB-enabled microcontroller, and for better equipped hackers out there, we’re even getting a Flipper Zero application you can employ instead. While we’ve seen some doubts that USB devices can be a proper attack vector, modern operating systems are more complex and bloated than even meets the eye, often for hardly any reason – for example, if you’re on Windows 10 or 11, press Ctrl+Shift+Alt+Win+L and behold. And, of course, you can make a hostile USB implant small enough that you can build them into a charger or a USB-C dock.

USB image: Inductiveload, Public domain.

Ultimate Power: Lithium-Ion Batteries In Series

April 4, 2024 by 52 Comments

At some point, the 3.6 V of a single lithium ion battery just won’t do, and you’ll absolutely want to stack LiIon cells in series. When you need high power, you’ve either got to increase voltage or current, and currents above say 10 A require significantly beefed up components. This is how you’re able to charge your laptop from your USB-C powerbank, for instance.

Or maybe you just need higher voltages, and don’t feel like using a step-up converter, which brings along with it some level of inefficiency. Whatever your reasons, it’s time to put some cells into series. Continue reading “Ultimate Power: Lithium-Ion Batteries In Series” →

The printer's display with the exploit-loaded animation playing, saying "hacked by blasty" and a bunch more stuff

A Fun Exploit For Canon Printers Brings GDB Gifts

April 4, 2024 by 12 Comments

Modern printers make it all that much more tempting to try and hack them — the hardware generally tends to be decent, but the firmware appears to be designed to squeeze as much money out of you as possible while keeping your annoyance level consistently high. That’s why it’s nice to see this exploit of the Canon imageCLASS MF74XCdw series (MF742Cdw/MF743Cdw) by [blasty], triggerable over a network connection, with a story for our amusement.

In this post, we get a tale of how this hack came out of a Pwn2Own Toronto challenge, notes on the hardware involved, and we’re shown the journey to a successful hack. The Canon printer OS is built without many of the protections, which makes playing with it easier than with more modernized targets, but it’s nevertheless not straightforward. Still, exploiting a couple things like the SOAP XML implementation and the UTF8 encoder nets you an ability to play nice animations on the display, and most certainly, control over the entirety of the hardware if you wanted it.

One of the most fun things about this hack is the GDB stub recently included in the repo. If you wanted to debug Canon printers for fun or profit, [blasty] brings you a GDB stub to do that comfortably, with a respectable README that even has porting notes for other Canon ImageCLASS printer models, should you lay your hands on a different machine of despair. WiFi connectivity appears to be enough for this hack, so you better make sure you don’t have your network-connected printers exposed on the Internet — not that you needed more reasons to avoid that.

PCB of the antenna about to be modded, with components desoldered and different parts of the circuit highlighted

Make A GPS Antenna Compatible With Same Manufacturer’s Receiver

April 3, 2024 by 9 Comments

GPS can be a bit complex of a technology – you have to receive a signal below the noise floor, do quite a bit of math that relies on the theory of relativity, and, adding insult to injury, you also have to go outside to test it. Have you ever wondered how GPS antennas work? In particular, how do active GPS antennas get power down the same wire that they use to send signal to the receiver? Wonder not, because [Tom Verbeure] gifts us a post detailing a mod letting a fancy active GPS antenna use a higher-than-expected input voltage.

[Tom]’s post has the perfect amount of detail – enough pictures to illustrate the entire journey, and explanations to go with all of it. The specific task is modifying a Symmetricom antenna to work with a Symmetricom GPS receiver, which has a puzzling attribute of supplying 12V to the antenna instead of more common 3.3V or 5V. There’s a few possible options detailed, and [Tom] goes for the cleanest possible one – replacing the voltage regulator used inside of the antenna.

With a suitable replacement regulator installed and a protection diode replaced, the antenna no longer registers as a short circuit, and gets [Tom] a fix – you, in turn, get a stellar primer on how exactly active GPS antennas work. If your device isn’t ready to use active GPS antennas, [Tom]’s post will help you understand another GPS antenna hack we covered recently – modifying the Starlink dish to use an active antenna to avoid jamming on the frontlines.