Running ARM Chips On Algae Power

May 14, 2022 by Al Williams 16 Comments

What’s the size of an AA battery and can run an ARM Cortex M0+ for six months? Well… probably an AA battery, but obviously, that wouldn’t be worth mentioning. But researchers at Cambridge have built a cell of blue-green algae that can do the job.

As you might expect, the algae need light, since they generate energy through photosynthesis. However, unlike conventional solar cells, the algae continue to produce energy in the dark at least for a while. Presumably, the algae store energy during the day and release it at night to survive naturally-occurring periods of darkness.

Generating power from photosynthesis isn’t a new idea since photosynthesis releases electrons. A typical cell has gold electrodes and a proton exchange membrane of some kind. You can see a video from Cambridge below about generating electricity from photosynthesis. Keep in mind, of course, that the Cortex M0+ is capable of very low power operation. Don’t look for that algae-powered spot welder anytime soon.

People tend to get fixated on electricity as energy, but there are other ways to harness photosynthesis. For example, we’ve seen algae fueling a chicken hole in the past. Not to mention we’ve seen algae used to power a robot in a novel and non-electrical way.

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Balloon Guitar Is An Absolute Gas, Helium Or Not

May 14, 2022 by Lewin Day 10 Comments

Guitars are most typically built out of wood. Whether it’s an acoustic guitar with a big open cavity, or a solid-body electric, there’s generally a whole lot of wood used in the construction. However, [Mattias Krantz] shows us that alternative construction methods are entirely possible, by building his own balloon guitar.

The balloon guitar still has a neck, bridge, and strings just like any other. However, in place of the resonant cavity of an acoustic guitar, there is provision to install a large balloon instead. It’s actually quite interesting to watch — with the balloon installed, the guitar delivers much more volume than when played without a resonant cavity at all.

The guitar was actually built to test if swapping out air in the balloon for helium would shift the pitch of the sound. Of course, a guitar’s pitch comes from the tension on the vibrating strings, so changing the gas in the resonant cavity doesn’t directly affect it. Instead, much like inhaling helium to affect the human voice, the change is to the timbre of the sound, not the fundamental pitch itself. It sounds as if the guitar has been given a subtle treble boost.

It’s a fun build, and one that shows us that it’s possible to build musical instruments in many ways, not just using traditional techniques. If you want to further play with your guitar’s sound, though, consider turning to the world of machine learning.

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MiniDisc Player Supports Full Data Transfer

May 14, 2022 by Bryan Cockfield 28 Comments

Between the era of the CD and the eventual rise and domination of streaming music platforms, there was a limbo period of random MP3 players mixed in with the ubiquitous (and now officially discontinued) iPod. In certain areas, though, the digital music player of choice was the MiniDisc, a miniature re-writable CD player with some extra digital features. Among them was the ability to transfer music to the discs over USB, but they did not feature the ability to transfer the songs back to a computer. At least until now, thanks to this impressive hack from [asivery].

Although it sounds straightforward, this trick has a lot of moving parts that needed to come together just right. The MiniDisc player uses a proprietary encoding format called ATRAC, so a codec is needed for that. The MiniDisc player stores data from the disc in a 40-second buffer when playing, so the code reads the data directly from DRAM in 40-second chunks, moves the read head, repeats the process as needed, then stitches the 40-second parts back together. It can work on any Sony NetMD portable, if you are lucky enough to still have one around.

The project is a tremendous asset to the MiniDisc community, especially since the only way to recover data from a MiniDisc player prior to this was to use a specific version known as the RH-1. As [asivery] reports, used RH-1 players are going for incredibly high prices partially because of this feature. Since this new method demonstrates that it’s possible to do with other devices, perhaps its reign in the MiniDisc world will come to a close. For those still outside the loop on this esoteric piece of technology, take a look at this MiniDisc teardown.

Thanks to [Maarten] for the tip!

stages of moving a wire and enveloping an object

Attack Of The Magnetic Slime Robots

May 14, 2022 by Anne Ogborn 6 Comments

[Li Zhang] and his colleagues at the Chinese University of Hong Kong (CUHK) have developed a blob of goo that can navigate complex surroundings, grow an ‘arm’, grasp a wire and move it, encapsulate a small object and carry it. As explained in the research paper, the secret is in the non-Newtonian material the bots are made of.

You can make a similar concoction at home, usually called “slime”, with corn starch and water. Deformed slowly, it will move like a fluid. Deformed rapidly, it behaves like an elastic solid. CUHK’s version is polyvinyl alcohol, glass coated NdFeB microparticles (neodymium magnets), and borax.

This dual behavior lets the robot do amazing things. Placed on a surface, they made the blob extend pseudopods by dragging underneath with a magnet, then used a circular field to make it grasp and transport a wire. They used a similar technique in the other axis to swallow an object. The CUHK group are promoting this as a way to retrieve foreign objects in the body (like an accidentally swallowed button cell).

Researchers will need to develop a non-toxic coating before it can be used in the body.

Nd magnets are made by sintering Nd2O3 or NdFeB in a strong magnetic field. Nd2O3 is available from SigmaAldrich at only slightly eye watering prices. Polyvinyl alcohol and borax are easily available. This seems like a hobbyist do-able project (Nd is toxic, use precautions).

We’ve been covering micro robots for some time. Back in 2014 we covered swarm micro robots. This project uses an external field to move a small Nd magnet, and all the way back in 2014 we covered early work in this field.

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TapType: AI-Assisted Hand Motion Tracking Using Only Accelerometers

May 14, 2022 by Dave Rowntree 16 Comments

The team from the Sensing, Interaction & Perception Lab at ETH Zürich, Switzerland have come up with TapType, an interesting text input method that relies purely on a pair of wrist-worn devices, that sense acceleration values when the wearer types on any old surface. By feeding the acceleration values from a pair of sensors on each wrist into a Bayesian inference classification type neural network which in turn feeds a traditional probabilistic language model (predictive text, to you and I) the resulting text can be input at up to 19 WPM with 0.6% average error. Expert TapTypers report speeds of up to 25 WPM, which could be quite usable.

Details are a little scarce (it is a research project, after all) but the actual hardware seems simple enough, based around the Dialog DA14695 which is a nice Cortex M33 based Bluetooth Low Energy SoC. This is an interesting device in its own right, containing a “sensor node controller” block, that is capable of handling sensor devices connected to its interfaces, independant from the main CPU. The sensor device used is the Bosch BMA456 3-axis accelerometer, which is notable for its low power consumption of a mere 150 μA.

User’s can “type” on any convenient surface.

The wristband units themselves appear to be a combination of a main PCB hosting the BLE chip and supporting circuit, connected to a flex PCB with a pair of the accelerometer devices at each end. The assembly was then slipped into a flexible wristband, likely constructed from 3D printed TPU, but we’re just guessing really, as the progression from the first embedded platform to the wearable prototype is unclear.

What is clear is that the wristband itself is just a dumb data-streaming device, and all the clever processing is performed on the connected device. Training of the system (and subsequent selection of the most accurate classifier architecture) was performed by recording volunteers “typing” on an A3 sized keyboard image, with finger movements tracked with a motion tracking camera, whilst recording the acceleration data streams from both wrists. There are a few more details in the published paper for those interested in digging into this research a little deeper.

The eagle-eyed may remember something similar from last year, from the same team, which correlated bone-conduction sensing with VR type hand tracking to generate input events inside a VR environment.

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Who Is Thinking About Open Source Firmware?

May 14, 2022 by Elliot Williams 23 Comments

Yesterday, we ran a post on NVIDIA’s announcement of open-source drivers for some of its most recent video cards. And Hackaday being huge proponents of open-source software and hardware, you’d think we’d be pouring the champagne. But it’s trickier than that.

Part of the reason that they are able to publish a completely new, open-source driver is that the secrets that they’d like to keep have moved into the firmware. So is the system as a whole more or less open? Yeah, maybe both.

With a more open interface between the hardware and the operating system, the jobs of people porting the drivers to different architectures are going to be easier. Bugs that are in what is now the driver layer should get found and fixed faster. All of the usual open-source arguments apply. But at the same time, the system as a whole isn’t all that much more transparent. The irony about the new NVIDIA drivers is that we’ve been pushing them to be more open for decades, and they’ve responded by pushing their secrets off into firmware.

Secrets that move from software to firmware are still secrets, and even those among us who are the most staunch proponents of open source have closed hardware and firmware paths in our computers. Take the Intel Management Engine, a small computer inside your computer that’s running all the time — even while the computer is “off”. You’d like to audit the code for that? Sorry. And it’s not like it hasn’t had its fair share of security relevant bugs.

And the rabbit hole goes deeper, of course. No modern X86 chips actually run the X86 machine language instructions — instead they have a microcode interpreter that reads the machine language and interprets it to what the chip really speaks. This is tremendously handy because it means that chip vendors can work around silicon bugs by simple pushing out a firmware update. But this also means that your CPU is running a secret firmware layer at core. This layer is of course not without bugs, some of which can have security relevant implications.

This goes double for your smartphone, which is chock-full of multiple processors that work more or less together to get the job done. So while Android users live in a more open environment than their iOS brethren, when you start to look down at the firmware layer, everything is the same. The top layer of the OS is open, but it’s swimming on top of an ocean of binary blobs.

How relevant any of this is to you might depend on what you intend to do with the device. If you’re into open source because you like to hack on software, having open drivers is a fantastic resource. If you’re looking toward openness for the security guarantees it offers, well, you’re out of luck because you still have to trust the firmware blindly. And if you’re into open source because the bugs tend to be found quicker, it’s a mix — while the top level drivers are made more inspectable, other parts of the code are pushed deeper into obscurity. Maybe it’s time to start paying attention to open source firmware?

An ATTiny board that one of the students developed for this project, etched on single-sided FR4.

Electronics And C++ Education With An ATTiny13

May 14, 2022 by Arya Voronova 28 Comments

When [Adam, HA8KDA] is not busy with his PhD studies, he mentors a group of students interested in engineering. To teach them a wide range of topics, he set out to build a small and entertaining embedded project as they watch and participate along the way. With this LED-adorned ATTiny13A project, [Adam] demonstrated schematic and PCB design, then taught C++ basics and intricacies – especially when it comes to building low-footprint software – and tied it all together into a real-world device students could take home after the project. His course went way beyond the “Hello world”s we typically expect, and some of us can only wish for a university experience like this.

He shares the PCB files and software with us, but also talks about the C++20 framework he’s developed for this ATTiny. The ATTiny13A is very cheap, and also very limited – you get 1K of ROM and 64 bytes of RAM. This framework lets you make good use of it, providing the basics like GPIO wiggling, but also things like low-power operation hooks, soft PWM with optional multi-phase operation support and EEPROM access. Students could write their own animations for this device, and he includes them in the repo, too!

In educational projects, it pays to keep code direct and clean, cruft-less and accessible to students. These are the things you can only achieve when you truly understand the tools you’re working with, which is the perfect position for teaching about them! [Adam] intends to show that C++ is more than suitable for low-resource devices, and tells us about the EEPROM class code he wrote – compiling into the same amount of instructions as an Assembly implementation and consuming the same amount of RAM, while providing compile-time checks and fail-safe syntax.

We’ve talked about using C++ on microcontrollers before, getting extra compile-time features without overhead, and this project illustrates the concept well. [Adam] asks us all, and especially our fellow C++ wizards, for our opinions on the framework he designed. Could you achieve even more with this simple hardware – make the code more robust, clean, have it do more within the limited resources?

What could you build with an ATTiny13, especially with such a framework? A flashy hairclip wearable, perhaps, or a code-learning RF-remote-controlled outlet. We’ve also seen a tiny camera trigger for endurance races,, a handheld Flappy Bird-like console, and many more!