Microcontrollers

2332 Articles

Plastic CPUs Will Bend To Your Will

June 21, 2022 by 25 Comments

As microcontroller prices drop, they appear in more things. Today you will find microcontrollers in your car, your household appliances, and even kid’s toys. But you don’t see them often embedded in things that are either super cheap or have to flex, such as for example a bandage. Part of the reason is the cost of silicon chips and part of the reason is that silicon chips don’t appreciate bending. What if you could make CPUs for less than a penny out of flexible plastic? What applications would that open up? PragmatIC — a company working to make this possible — thinks it would open up a whole new world of smart items that would be unthinkable today. They worked with a team at the University of Illinois Urbana-Champaign to create prototype plastic CPUs with interesting results.

This is still the stuff of research and dreams, but a team of researchers did work to produce 4-bit and 8-bit processors using IGZO –indium gallium zinc oxide — semiconductor technology. This tech can be put on plastic and will work even if you bend it around a radius as small as a few millimeters.

Continue reading “Plastic CPUs Will Bend To Your Will” →

Blinking An Arduino LED, In Julia

June 20, 2022 by 11 Comments

The Julia programming language is a horrible fit for a no-frills microcontroller like the ATMega328p that lies within the classic Arduino, but that didn’t stop [Sukera] from trying, and succeeding.

All of the features that make Julia a cool programming language for your big computer make it an awful choice for the Arduino. It’s designed for interactivity, is dynamically typed, and leans heavily on its garbage collection; each of these features alone would tax the Mega to the breaking point. But in its favor, it is a compiled language that is based on LLVM, and LLVM has an AVR backend for C. Should just be a simple matter of stubbing out some of the overhead, recompiling LLVM to add an AVR target for Julia, and then fixing up all the other loose ends, right?

Well, it turns out it almost was. Leaning heavily on the flexibility of LLVM, [Sukera] manages to turn off all the language features that aren’t needed, and after some small hurdles like the usual problems with volatile and atomic variables, manages to blink an LED slowly. Huzzah. We love [Sukera’s] wry “Now THAT is what I call two days well spent!” after it’s all done, but seriously, this is the first time we’ve every seen even super-rudimentary Julia code running on an 8-bit microcontroller, so there are definitely some kudos due here.

By the time that Julia is wedged into the AVR, a lot of what makes it appealing on the big computers is missing on the micro, so we don’t really see people picking it over straight C, which has a much more developed ecosystem. But still, it’s great to see what it takes to get a language designed around a runtime and garbage collection up and running on our favorite mini micro.

Thanks [Joel] for the tip!

Diagram of the LTC protocol, showing the difference between 1 bits and 0 bits - both transmitted using one up and one down pulse, but with '1' bit pulses being half as short.

Animate Arcane Protocols With Interrupt-Backed Bitbanging

June 19, 2022 by 10 Comments

We often take our “SoftwareSerial” libraries for granted, and don’t investigate what goes on under the hood — until they fail us, at least. Would you like to learn how to harness the power of interrupt-driven bitbanging? [Jim Mack] teaches us how to make our protocol implementations fly using the LTC protocol as a springboard.

LTC (Linear/[Longitudinal] TimeCode) is a widely-used and beautifully-crafted protocol that tends to fly under our radar, and is one that hackers could learn plenty from. It’s used for synchronization of audio/video devices during media production and playback. LTC’s signal is almost digital but not quite: it doesn’t need a clock, and it has no polarity. Additionally, it mimics an audio signal really well, you can decode it at any playback speed, and many other benefits and quirks that [Jim] outlines. You do need to maintain the timings, though, and [Jim]’s article shows us how to keep them right while not inconveniencing your primary tasks.

Continue reading “Animate Arcane Protocols With Interrupt-Backed Bitbanging” →

Kved: An Embeddable Key/Value Datastore

June 14, 2022 by 7 Comments

At some point when developing embedded applications, you’re going to want to store unique values in non-volatile memory, values that can’t be fixed at compilation time. Many microcontrollers have a small amount of EEPROM memory for this very purpose, but it’s usually rather limited if it’s provided at all. Even if you do have a bit of space on an EEPROM at your disposal, actually formatting your values into the memory and dealing with the pesky problem of wear leveling (necessary for parameters that need to change often) can be a bit of a hassle.

Lucky for us, [Marcelo Barros] decided to share his own implementation, Kved (key/value database) which uses the flash memory instead for such storage. Kved implements a dictionary type data structure, using numeric keys and values, supporting a few integer types. Using the library should be straightforward enough, as [Marcelo] says, all you need are a pair of spare flash sectors and the ability to port the flash the sector read, write, and erase functions. There are plenty of examples of such code available for practically any microcontroller out there, so that should be no barrier. For those who want to play with it right now, the repo currently has ports for the STM32L433RC and STM32F411CE, as well as a simulated version you can compile and run on your computer.

From an implementation perspective, the write algorithm uses a COW (Copy On Write) method. Changed values are invalidated by over-writing the storage location with all-zeros, and re-writing the changed value to a new location, cycling through the unused locations until the sector is full. Data-integrity mechanisms are implemented, preventing corruption of the data structure due to power fail situations, so incorrectly written values will be corrected on start-up and not affect the integrity of the configuration.

When looking around, we found a similar project, Embedis, over on hackaday.IO, as well as this article on the subject of embedded filesystems from a little while back.

Raspberry Pi Pico Replaces PlayStation Memory Card

June 13, 2022 by 16 Comments

It’s almost hard to believe these days, what with modern game consoles packing terabytes of internal storage, but there was a time when the totality of your gaming career would be stored on an external memory card that held just a few megabytes of save data. Of course, before that you had to write down a sequence of random letters and numbers to pick up where you left off, but that’s a story for another day.

While the memory card concept might be quaint to the modern gamer, its modular nature does provide the hacker with some interesting avenues to explore. For example, take a look at the very impressive PicoMemcard project from [Daniele Giuliani]. Hardware wise, it doesn’t get much simpler than this. You just take the PCB from a cheap (or dead) PlayStation memory card, and solder seven jumpers to the edge connector contacts so you can plug them into the Pico. Then you’ve just got to upload the firmware to the Pico, and you’re done. Continue reading “Raspberry Pi Pico Replaces PlayStation Memory Card” →

EC Hacking: Your Laptop Has A Microcontroller

June 7, 2022 by 25 Comments

Recently, I stumbled upon a cool write-up by [DHowett], about reprogramming a Framework laptop’s Embedded Controller (EC). He shows us how to reuse the Caps Lock LED, instead making it indicate the F1-F12 key layer state – also known as “Fn lock”, AKA, “Does your F1 key currently work as F1, or does it regulate volume”. He walks us through adding custom code to your laptop’s EC firmware and integrate it properly into the various routines the EC runs.

The EC that the Framework uses is a MEC1521 chip from Microchip, and earlier this year, they open-sourced the firmware for it. Now, there’s a repository of microcontroller code that you can compile yourself, and flash your Framework laptop’s motherboard with. In a comment section of HackerNews, a Framework representative has speculated that you could add GPIOs to a Framework motherboard through EC firmware hacking.

Wait… Microcontroller code? GPIOs? This brings us to the question – what is the EC, really? To start with, it’s just a microcontroller. You can find an EC in every x86 computer, including laptops, managing your computer’s lower-level functions like power management, keyboard, touchpad, battery and a slew of other things. In Apple land, you might know them as SMC, but their function is the same.

Why have we not been reprogramming our ECs all this time? That’s a warranted question, too, and I will tell you all about it.

Continue reading “EC Hacking: Your Laptop Has A Microcontroller” →

Universal TFT Display Backpack Helps Small Displays Shine

June 4, 2022 by 16 Comments

TFT technology might be ancient news for monitors and TVs, but it’s alive and well when it comes to hobbyist electronics and embedded devices. They’ve now become even easier to integrate, thanks to the Universal TFT Display Backpack design by [David Johnson-Davies].

Breakout board, compatible with pinouts of most small TFT displays.

Such displays are affordable and easy to obtain, and [David] noticed that many seemed to have a lot in common when it came to pinouts and hookup info. The result is his breakout board design, a small and easy-to-assemble PCB breakout board that can accommodate the pinouts of a wide variety of TFT displays available from your favorite retailers or overseas sellers.

The board has a few quality-of-life features such as an optional connection for a backlight, and a staggered pin pattern so that different TFT boards can be pushed in to make a solid connection without soldering. That’s very handy for testing and evaluating different displays.

Interested? Head on over to the GitHub repository for the project, and while you’re at it, check out [David]’s Tiny TFT Graphics Library 2 which is a natural complement to the display backpack. [David] sure knows his stuff when it comes to cleverly optimized display work; we loved his solution for writing to OLED displays without needing a RAM buffer.