Multispectral Imaging System Built With Raspberry Pi

August 25, 2022 by Lewin Day 10 Comments

Multispectral imaging can be a useful tool, revealing all manner of secrets hidden to the human eye. [elad orbach] built a rig to perform such imaging using the humble Raspberry Pi.

The project is built inside a dark box which keeps outside light from polluting the results. A camera is mounted at the top to image specimens installed below, which the Pi uses to take photos under various lighting conditions. The build relies on a wide variety of colored LEDs for clean, accurate light output for accurate imaging purposes. The LEDs are all installed on a large aluminium heatsink, and can be turned on and off via the Raspberry Pi to capture images with various different illumination settings. A sheath is placed around the camera to ensure only light reflected from the specimen reaches the camera, cutting out bleed from the LEDs themselves.

Multispectral imaging is particularly useful when imaging botanical material. Taking photos under different lights can reveal diseases, nutrient deficiencies, and other abnormalities affecting plants. We’ve even seen it used to investigate paintings, too. Video after the break.

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Pi Pico Gives Its Life For Overclocking

August 25, 2022 by Al Williams 14 Comments

How fast can a Raspberry Pi Pico go? Well, apparently the answer is 1 GHz if you freeze it and give it over twice the voltage it normally gets. Oh, one catch. After a few minutes, the chip will fry itself.

That’s the results reported by [David] who took a Peltier cooler and a pretty serious over-voltage. The dhrystone scores went from around 200 to over 1100. Of course, there’s that pesky early death to worry about, so you probably won’t want to try this at home.

Even before the chip bites the dust, there are other problems to address. For example, once you get much over 250 MHz, the Pico’s SPI flash can’t keep up, so all the software you want to run has to be put in RAM first. You’ll also want to do some poking at the system clock parameters.

Honestly, we enjoy overclocking PCs or just about anything else. The good news is if you fry a Pico, it won’t make a sizable dent in your wallet. It is also a fun way to learn a bit more about the internals of the processor. According to [David], the cooler took the part to -40 C. We wonder how it would fare in a bath of LN₂?

Of course, you can push a regular Pi, too. If you really need a 1 GHz overclocked microcontroller, maybe check out the Teensy.

Tech In Plain Sight: Rain-Sensing Wipers

August 25, 2022 by Al Williams 37 Comments

While it is definitely a first-world problem that you don’t want to manually turn on your windshield wipers when it starts raining, it is also one of those things that probably sounds easier to solve than it really is. After all, you can ask a four-year-old if it is raining and expect a reasonable answer. But how do you ask that question of a computer? Especially a tiny cheap computer that is operating pretty much on its own.

You might want to stop here and try to think of how you’d do it. Measure the conductivity of the glass? Maybe water on the glass affects its dielectric constant and you could measure the resulting capacitance? Modern cars don’t do either. The problem is complicated because you need a solution that works with the glass and isn’t prone to false positives due to dirt or debris.

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Printable One-Way Driver Skips Ratchet For A Clutch

August 25, 2022 by Lewin Day 6 Comments

Ratcheting screwdrivers can help you work faster, even if their bulk means they’re not the best option for working in tight spaces. [ukman] decided to build a similar device of his own, relying on a slightly different mechanism — an overrunning clutch.

The design is similar to a freewheel used on a bicycle, allowing free movement in one direction while resisting it in the other. As the screwdriver is turned in one direction, the shaft is wedged by a series of cylinders that lock it in place. However, the geometric shape of the clutch allows the shaft to turn in the other direction without getting wedged in place. The result is a screwdriver that can be turned, rolled back, and turned further. Thus, screws can be tightened without loosening one’s grip on the tool.

With its 3D printed construction, it’s probably not the best tool for heavy-duty, high-torque jobs, but it looks more than capable of handling simple assembly tasks. We’ve seen some other nifty screwdrivers around these parts, too.

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I3C — No Typo — Wants To Be Your Serial Bus

August 25, 2022 by Al Williams 67 Comments

Remember old hard drives with their giant ribbon cables? They went serial and now the power cables are way thicker than the data cables. We’ve seen the same thing in embedded devices. Talking between chips these days tends to use I2C or SPI or some variation of these to send and receive data over a handful of pins. But now there is I3C, a relatively new industry standard that is getting a bit of traction.

I2C and SPI are mature but they do have problems. I2C can be relatively slow and SPI usually requires extra pins for each device. Besides that, there is poor support for adding and removing devices dynamically or discovering devices automatically.

I3C, created by the MIPI Alliance, aims to fix these problems. It does use the usual two wires, SCL for the clock and SDA for data. One device acts as a controller. Other devices can be targets or secondary controllers. It is also backward compatible with I2C target devices. Depending on how you implement it, speeds can be quite fast with a raw speed of 12.5 Mbps and using line coding techniques can go to around 33 Mbps.

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Everything You Didn’t Know You Need To Know About Glitching Attacks

August 25, 2022 by Dan Maloney 1 Comment

If you’ve always been intrigued by the idea of performing hardware attacks but never knew where to start, then we’ve got the article for you: an in-depth look at the hows and whys of hardware glitching.

Attentive readers will recall that we’ve featured [Matthew Alt]’s reverse engineering exploits before, like the time he got root on a Linux-based arcade cabinet. For something a bit more challenging, he chose a Trezor One crypto wallet this time. We briefly covered a high-stakes hack (third item) on one of these wallets by [Joe Grand] a while back, but [Matthew] offers much, much more detail.

After introducing the theory of glitching attacks, which seek to force a processor into an undefined state using various methods, [Matthew] discusses the specifics of the Trezor wallet and how the attack was planned.

His target — the internal voltage regulator of the wallet’s STM32 microcontroller — required desoldering a few caps before the attack could begin, which was performed with a ChipWhisperer. After resolving a few initial timing issues, he was able to glitch the chip into dropping to the lowest level of readout protection, which gave access to the dongle’s SRAM through an ST-Link debugger.

While this summary may make the whole thing sound trivial, it’s obvious that the attack was anything but, nor was the effort that went into writing it all up. The whole thing reads a little like a techno-thriller, and there’s plenty of detail there if you’re looking for a tutorial on chip glitching. We’re looking forward to part 2, which will concentrate on electromagnetic fault-injection using a PicoEMP and what looks like a modified 3D printer.

PET Bottles Diligently Turned Into Filament

August 25, 2022 by Bryan Cockfield 21 Comments

While the price of 3D printers has come down quite a lot in the past few years, filament continues to be rather pricey especially for those doing a lot of printing. This has led to some people looking to alternatives for standard filament, including recycling various forms of plastic. We’ve seen plenty of builds using various materials, but none so far have had this level of quality control in the final project.

What sets this machine apart from others is that it’s built around an Arduino Nano and includes controls that allow the user to fine-tune a PID controller during the conversion of the recycled plastic into filament. Different plastic bottles have different material qualities, so once the machine is started it can be adjusted to ensure that the filament produced has the exact specifications for the printer. The PCB is available for download, and the only thing that needs to be done by hand besides feeding the machine to start it is to cut the plastic into strips for the starter spool. There is also a separate 3D printed tool available to make this task easy, though.

Not only could this project save printing costs, but it also keeps harmful plastics out of landfills and other environments. Recycling plastic tends to be quite difficult since producing new plastic is incredibly cheap, and the recycled material can’t be used as often as other materials such as aluminum. But there are still plenty of people out there trying to reuse as much of it as they can.

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