Universal Bio-Electrical Signal Amplifier Makes Reading Body Signals Easy

August 26, 2021 by 18 Comments

The electrical signals emitted by the human body tell us a lot about what’s going on inside. But getting those signals inside your microcontroller is not straightforward: the voltages are too small for most ADCs, and the ever-present 50 or 60 Hz mains frequency makes it hard to discern subtle changes. Over at Upside Down Labs, [Deepak Kathri] developed a universal biosensor interface called the BioAmp EXG Pill to make all this a lot easier.

Its name refers to the fact that it can be used for several different bio-electrical sensing applications: ECG, EMG, EOG and EEG, which deal with signals coming from the heart, muscles, eyes and brain, respectively. To enable such flexibility, the board has connectors for two or three electrodes, as well as solder pads to mount resistors and capacitors to adjust the gain and bandwidth. An instrumentation amplifier increases the strength of the desired signal while rejecting noise and interference.

The form factor allows easy connection to electrodes on one side and a data acquisition system on the other. Measuring just 25.4 mm long and 10 mm wide, it should be easy to integrate into any type of biosensing gizmo you can come up with. [Deepak] has made several demo setups, showing him using the Pill with an Arduino to measure his heart rate, detect eye blinks, and even control a robot arm using his own arm muscles!

The EXG Pill is an evolution of an earlier EMG-only project. We’ve seen several great ECG and EEG projects before, but is the first time we’ve seen one amplifier that can do them all.

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EXPS/2 Keyboard Adapter Translates PS/2 And USB To MSX

August 2, 2021 by 10 Comments

Say what you will about suitcase computers, but at least most of them still have their keyboards with them. [danjovic] has this vintage Brazilian computer from the 1980s called a Gradiente Expert. These were MSX machines with Z80 chips that ran BASIC, DOS, and CP/M, and they looked like state-of-the-art dual-deck stereo systems. You can still find them pretty easily, but sadly, most of them have lost their rad mechanical keyboard with its giant arrow keys and proprietary connector.

If you now want to get one of these awesome pieces of computing history and would like to be able to talk to it, [danjovic] has you covered with the open-source EXPS/2 keyboard adapter. It will allow you to connect either a PS/2 keyboard or a USB keyboard in fallback mode to the Expert using an ATMega328P and a bespoke DIN-13 to DB-13 cable. As it turns out, there’s a wealth of information on MSX keyboard matrices out there.

How much do you know about the USB keyboard interface? If you want a warehouse of information delivered to your brain in the most pleasant way possible, go watch [Ben Eater] break it down with pen and paper.

Are Hackers Being Let Down In Education?

July 23, 2021 by 62 Comments

In my work for Hackaday over the years I have been privileged to interact with some of the most creative people I have ever met, I have travelled far more than I ever did when I toiled unseen in an office in Oxford, and I have been lucky enough to hang out in our community’s spaces, camps, and dives across Europe.

Among the huge diversity of skills and ideas though, it’s striking how many of us share similar experiences and histories that have caused us to find our people in rooms full of tools and 3D printers. One of these things I found surprising because I thought I was the only one; I never fit in with the other kids at school, I found much of the teaching incomprehensible and had to figure things out for myself. As an exercise recently I did a straw poll among some of my friends, and found that a significant majority had a similar experience. Clearly something must have gone badly wrong in the way we were being taught that so many of us could have been let down by our schooling, and maybe to understand the needs of our community it’s time to understand why.

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Tech Hidden In Plain Sight: Cruise Control

July 8, 2021 by 29 Comments

The advent of the microcontroller changed just about everything. Modern gadgets often have a screen-based interface that may hide dozens or hundreds of functions that would have been impractical and confusing to do with separate buttons and controls. It also colors our thinking of what is possible. Imagine if cars didn’t have cruise control and someone asked you if it were possible. Of course. Monitor the speed and control the gas using a PID algorithm. Piece of cake, right? Except cruise control has been around since at least 1948. So how did pre-microcontroller cruise control work? Sure, in your modern car it might work just like you think. But how have we had seventy-plus years of driving automation?

A Little History

A flyball governor from a US Navy training film.

Controlling the speed of an engine is actually not a very new idea. In the early 1900s, flyball governors originally designed for steam engines could maintain a set speed. The idea was that faster rotation caused the balls would spread out, closing the fuel or air valve while slower speeds would let the balls get closer together and send more fuel or air into the engine.

The inventor of the modern cruise control was Ralph Teetor, a prolific inventor who lost his sight as a child. Legend has it that he was a passenger in a car with his lawyer driving and grew annoyed that the car would slow down when the driver was talking and speed up when he was listening. That was invented in 1948 and improved upon over the next few years.

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Adding A Gentle Touch To Prosthetic Limbs With Somatosensory Stimulation

June 30, 2021 by 5 Comments

When Nathan Copeland suffered a car accident in 2004, damage to his spinal cord at the C5/C6 level resulted in tetraplegic paralysis. This left him initially at the age of 18 years old to consider a life without the use of his arms or legs, until he got selected in 2014 for a study at the University of Pittsburgh involving the controlling of a robotic limb using nothing but one’s mind and a BCI.

While this approach, as replicated in various other studies, works well enough for simple tasks, it comes with the major caveat that while it’s possible to control this robotic limb, there is no feedback from it. Normally when we try to for example grab an object with our hand, we are aware of the motion of our arm and hand, until the moment when our fingers touch the object which we’re reaching for.

In the case of these robotic limbs, the only form of feedback was of the visual type, where the user had to look at the arm and correct its action based on the observation of its position. Obviously this is far from ideal, which is why Nathan hadn’t just been implanted with Utah arrays that read out his motor cortex, but also arrays which connected to his somatosensory cortex.

As covered in a paper by Flesher et al. in Nature, by stimulating the somatosensory cortex, Nathan has over the past few years regained a large part of the sensation in his arm and hand back, even if they’re now a robotic limb. This raises the question of how complicated this approach is, and whether we can expect it to become a common feature of prosthetic limbs before long. Continue reading “Adding A Gentle Touch To Prosthetic Limbs With Somatosensory Stimulation” →

PipeWire, The Newest Audio Kid On The Linux Block

June 23, 2021 by 65 Comments

Raise your hand if you remember when PulseAudio was famous for breaking audio on Linux for everyone. For quite a few years, the standard answer for any audio problem on Linux was to uninstall PulseAudio, and just use ALSA. It’s probably the case that a number of distros switched to Pulse before it was quite ready. My experience was that after a couple years of fixing bugs, the experience got to be quite stable and useful. PulseAudio brought some really nice features to Linux, like moving sound streams between devices and dynamically resampling streams as needed.

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Mind-Controlled Flamethrower

May 12, 2021 by 16 Comments

Mind control might seem like something out of a sci-fi show, but like the tablet computer, universal translator, or virtual reality device, is actually a technology that has made it into the real world. While these devices often requires on advanced and expensive equipment to interpret brain waves properly, with the right machine learning system it’s possible to do things like this mind-controlled flame thrower on a much smaller budget. (Video, embedded below.)

[Nathaniel F] was already experimenting with using brain-computer interfaces and machine learning, and wanted to see if he could build something practical combining these two technologies. Instead of turning to an EEG machine to read brain patterns, he picked up a much less expensive Mindflex and paired it with a machine learning system running TensorFlow to make up for some of its shortcomings. The processing is done by a Raspberry Pi 4, which sends commands to an Arduino to fire the flamethrower when it detects the proper thought patterns. Don’t forget the flamethrower part of this build either: it was designed and built entirely by [Nathanial F] as well using gas and an arc lighter.

While the build took many hours of training to gather the proper amount of data to build the neural network and works as the proof of concept he was hoping for, [Nathaniel F] notes that it could be improved by replacing the outdated Mindflex with a better EEG. For now though, we appreciate seeing sci-fi in the real world in projects like this, or in other mind-controlled projects like this one which converts a prosthetic arm into a mind-controlled music synthesizer.

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