Hackaday Prize 2023: Over-the-Top Programmable Resistor Looks The Part And Performs

August 18, 2023 by Dan Maloney 18 Comments

Every once in a while we get wind of a project that we’re reluctant to write up for the simple reason that it looks too good to be true. Not that projects need to be messy to be authentic, mind you, but there are some that are just so finished and professional looking that it gives us a bit of pause. [Sebastian]’s programmable precision resistor is a shining example of such a project

While [Sebastian] describes this as “a glorified decade resistance box,” and technically that’s exactly right — at its heart it’s just a bunch of precision resistors being switched into networks to achieve a specific overall resistance — there’s a lot more going on here than just that. The project write-up, which has been rolling out slowly over the last month or so, has a lot of detail on different topologies that could have been used — [Sebastian] settled on a switched series network that only requires six relays per decade while also minimizing the contribution of relay contact resistance to the network. Speaking of which, there’s a detailed discussion on that subject, plus temperature compensation, power ratings, and how the various decades are linked together.

For as much that’s interesting about what’s under the hood, we’d be remiss to not spend a little time praising the exterior of this instrument. [Sebastian] appears to have spared no expense to make this look like a commercial product, from the rack-mount enclosure to the HP-esque front panel. The UI is all discrete pushbuttons and knobs with a long string of 16-segment LEDs — no fancy touch-screens here. The panel layout isn’t overly busy, and looks like it would be easy to use with some practice. We’d love to hear how the front and rear panel overlays were designed, too; maybe in a future project update.

This honestly looks like an instrument that you’d pay a princely sum to Keithley or H-P to own, at least back in the late 1990s or so. Kudos to [Sebastian] for the attention to detail here.

STM32 Oscilloscope Uses All The Features

August 8, 2023 by Bryan Cockfield 29 Comments

[jgpeiro] is no slouch when it comes to building small, affordable oscilloscopes out of common microcontrollers. His most recent, based on an RP2040 with two channels that ran at 100 MSps, put it on the order of plenty of commercially-available oscilloscopes at this sample rate but at a fraction of the price. He wanted to improve on the design though, making a smaller unit with a greatly reduced bill-of-materials and with a more streamlined design, so he came up with this STM32-based oscilloscope.

The goal of this project was to base as many of the functions around the built-in capabilities of the STM32 as possible, so in addition to the four input channels and two output channels running at 1 MHz, the microcontroller also drives a TFT display which has been limited to 20 frames per second to save processor power for other tasks. The microcontroller also has a number of built-in operational amplifiers which are used as programmable gain amplifiers, further reducing the amount of support circuitry needed on the PCB while at the same time greatly improving the scope’s capabilities.

In fact, the only parts of consequence outside of the STM32, the power supply, and the screen are the inclusion of two operational amplifiers included to protect the input channels from overvoltage events. It’s an impressive build in a small form factor, and we’d say the design goal of keeping the parts count low has been met as well. If you do need something a little faster though, his RP2040-based oscilloscope is definitely worth checking out.

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Blinkenlights To Bootloader: A Guide To STM32 Development

August 6, 2023 by Bryan Cockfield 15 Comments

While things like the Arduino platform certainly opened up the gates of microcontroller programming to a much wider audience, it can also be limiting in some ways. The Arduino IDE, for example, abstracts away plenty of the underlying machinations of the hardware, and the vast amount of libraries can contribute to this effect as well. It’s not a problem if you just need a project to get up and running, in fact, that’s one of its greatest strengths. But for understanding the underlying hardware we’d recommend taking a look at something like this video series on the STM32 platform.

The series comes to us from [Francis Stokes] of Low Byte Productions who has produced eighteen videos for working with the STM32 Cortex-M4 microcontroller. The videos start by getting a developer environment up and blinking LEDs, and then move on to using peripherals for more complex tasks. The project then moves on to more advanced topics and divides into two parts, the development of an application and also a bootloader. The bootloader begins relatively simply, and then goes on to get more and more features built into it. It eventually can validate and update firmware, and includes cryptographic signing (although [Francis] notes that you probably shouldn’t use this feature for production).

One of the primary goals for [Francis], apart from the actual coding and development, was to liven up a subject matter that is often seen as dry, which we think was accomplished quite well. A number of future videos are planned as well. But, if you’re not convinced that the STM32 platform is the correct choice for you, we did publish a feature a while back outlining a few other choices that might provide some other options to consider.

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Networking With Balloons

June 26, 2023 by Bryan Cockfield 14 Comments

Starlink has been making tremendous progress towards providing world-wide access to broadband Internet access, but there are a number of downsides to satellite-based internet such as the cluttering of low-Earth orbit, high expense, and moodiness of CEO. There are some alternatives if standard Internet access isn’t available, and one of the more ambitious is providing Internet access by balloon. Project Loon is perhaps the most famous of these (although now defunct), but it’s also possible to skip the middleman and build your own high-altitude balloon capable of connection speeds of 500 Kbps.

[Stephen] has been working on this project for a few months and while it doesn’t support a full Internet connection, the downlink on the high altitude balloon is fast enough to send high-resolution images in near-real-time. This is thanks to a Raspberry Pi Zero on board the balloon that is paired with an STM32 board which handles the radio communication on a RF4463 transceiver module. The STM32 acts as an intermediary or buffer to ensure reliable information is sent out on the radio, rather than using the Pi directly. [Stephen] also wrote a large chunk of the software responsible for handling all of these interactions, optimized for balloon flight specifically.

The blog post for this project was written a few weeks ago with a reported first launch date for the system already passed, so we will eagerly anticipate the results and the images he was able to gather using this system. Eventually [Stephen] hopes the downlink will be fast enough for video as well.Balloons are an underappreciated tool as well, and this isn’t the only way that they can be used to help send radio signals from place to place.

Hackaday Prize 2023: Learn DSP With The Portable All-in-One Workstation

May 16, 2023 by Joseph Long 8 Comments

Learning Digital Signal Processing (DSP) techniques traditionally involves working through a good bit of mathematics and signal theory. To promote a hands-on approach, [Clyne] developed the DSP PAW (Portable All-in-one Workstation). DSP PAW hardware and software provide a complete learning environment for any computer where DSP algorithms can be entered as C++ code through an Arduino-like IDE.

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The New Hotness

May 6, 2023 by Elliot Williams 35 Comments

If there’s one good thing to be said about the chip shortage of 2020-2023 (and counting!) it’s that a number of us were forced out of our ruts, and pushed to explore parts that we never would have otherwise. Or maybe it’s just me.

Back in the old times, I used to be a die-hard Atmel AVR fan for small projects, and an STM32 fan for anything larger. And I’ll freely admit, I got stuck in my ways. The incredible abundance of dev boards in the $2 range also helped keep me lazy. I had my thing, and I was fine sticking with it, admittedly due to the low price of those little blue pills.

And then came the drought, and like everyone else, my stockpile of microcontrollers started to dwindle. Replacements at $9 just weren’t an option, so I started looking around. And it’s with no small bit of shame that I’ll admit that I hadn’t been keeping up with the changes as much as I should have. Nowadays, it’s all ESP32s and RP2040s over here, and granted there’s a bit of a price bump, but the performance is there in abundance. But I can’t help feeling like I’m a few years back of the cutting edge.

So when I see work like what [CNLohr] and [Bitluni] are doing with the ultra-cheap CH32V003 microcontrollers, it makes me think that I need to start filling in gaps in my comfortable working-set of chips again. But how the heck am I supposed to keep up? And how do you? It took a global pandemic and silicon drought to force me out of my comfort zone last time. Can the simple allure of dirt-cheap chips get me out? We’ll see!

Hackaday Links: April 9, 2023

April 9, 2023 by Dan Maloney 17 Comments

When it comes to cryptocurrency security, what’s the best way to secure the private key? Obviously, the correct answer is to write it on a sticky note and put it on the bezel of your monitor; nobody’ll ever think of looking there. But, if you’re slightly more paranoid, and you have access to a Falcon 9, you might just choose to send it to the Moon. That’s what is supposed to happen in a few months’ time, as private firm Lunar Outpost’s MAPP, or Mobile Autonomous Prospecting Platform, heads to the Moon. The goal is to etch the private key of a wallet, cheekily named “Nakamoto_1,” on the rover and fund it with 62 Bitcoins, worth about $1.5 million now. The wallet will be funded by an NFT sale of space-themed electronic art, because apparently the project didn’t have enough Web3.0 buzzwords yet. So whoever visits the lunar rover first gets to claim the contents of the wallet, whatever they happen to be worth at the time. Of course, it doesn’t have to be a human who visits.

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