A Guide To Making The Right Microcontroller Choice

Starting a new microcontroller project can be pretty daunting. While you have at least a rough idea of where you want to end up, there are so many ways to get there that you can get locked into “analysis paralysis” and never get the project off the ground. Or arguably worse, you just throw whatever dev board you have in the junk bin and deal with the consequences.

While it’s hard to go wrong with relying on a familiar MCU and toolchain, [lcamtuf] argues in this recent guide to choosing microcontrollers that it’s actually not too much of a chore to make the right choice. Breaking the microcontroller universe down into three broad categories makes the job a little easier: simple process control, computationally intensive tasks, and IoT products. Figuring out where your project falls on that spectrum narrows your choices considerably.

For example, if you just need to read some sensors and run a few servos or solenoids, using something like a Raspberry Pi is probably overkill. On the other hand, a Pi or other SBC might be fine for something that you need wireless connectivity. We also appreciate that [lcamtuf] acknowledges that intangible considerations sometimes factor in, such as favoring a new-to-you MCU because you’ll get experience with technology you haven’t used before. It might not override technical considerations by itself, but you can’t ignore the need to stretch your wings once in a while.

There’s nothing earth-shattering here, but we enjoy think pieces like this. It’s a bit like [lcamtuf]’s recent piece on rethinking your jellybean op-amps.

OpenWRT To Mark 20 Years With Reference Hardware

The OpenWRT project is now two decades old. The project has come a long way since Linksys was forced to release the GNU-licensed code for the original WRT54G router from which the project takes its name. They’ve marked the occasion in an interesting manner: by proposing that the plethora of devices supported by the OS be joined by a fully upstream-supported reference hardware platform.

Spec-wise it’s what you would expect for a hackable router platform in 2024. A MediaTek chipset can be found at its centre, but the hardware is not in this case the important bit. Here will be a platform that won’t have to rely on proprietary manufacturer BLOBs, and which will thus likely continue to have up-to-date kernel support long into the future. So many enticing SBCs fall in this regard, and many retain ossified kernel versions after their manufacturers tire of them as a result.

It appears that the future of this project will be subject to an OpenWRT community vote, and we sincerely hope that it will come to fruition. Meanwhile, we couldn’t resist a peek at the status of the router that started it all, by our reckoning the original WRT54G was last supported by the OS over a decade ago.

New Part Day: Flush-mount Touchscreen For Retro PC Build

I recently had the opportunity to purchase an early version of a new display, and it happened to be just the thing I needed to make a project work. That display is the Elecrow 11.6″ CrowVision touchscreen slated for release in 2024. Preorders are being accepted on Crowd Supply.

I had an idea for a retro-inspired PC build that was just waiting for a screen like this. I’ll talk about the display and what’s good about it, then showcase the build for which it was the missing piece. If you’ve got a project waiting for something similar, maybe this part will provide what you need or at least turn on some new ideas.

What Is It?

The CrowVision 11.6″ 1366 x 768 touchscreen has an HDMI input, USB output for touch data, and accepts 12 V DC. It’s made to interface easily with a Raspberry Pi or other SBC (single-board computer).

Personally I consider a display like this to be the minimum comfortable size for using desktop type applications in a windowed environment. Most displays in this space are smaller. But aside from that, what helps make it useful for embedding into a custom enclosure is the physical layout and design.

Since I was looking for the largest display that could be flush-mounted in an enclosure without a lot of extra space around the display’s sides, it was just what I needed. The integrated touchscreen is a nice bonus.

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RetroPie, Without The Pi

The smart television is an interesting idea in theory. Rather than having the cable or satellite company control all of the content, a small computer is included in the television itself to host and control various streaming clients and other services. Assuming you have control of the software running on the computer, and assuming it isn’t turned into a glorified targeted advertising machine, this can revolutionize the way televisions are used. It’s even possible to turn a standard television into a smart TV with various Android devices, and it turns out there’s a lot more you can do with these smart TV contraptions as well.

With most of these devices, a Linux environment is included running on top of an ARM platform. If that sounds similar to the Raspberry Pi, it turns out that a lot of these old Android TV sets are quite capable of doing almost everything that a Raspberry Pi can do, with the major exception of GPIO. That’s exactly what [Timax] is doing here, but he notes that one of the major hurdles is the vast variety of hardware configurations found on these devices. Essentially you’d have to order one and hope that you can find all the drivers and software to get into a usable Linux environment. But if you get lucky, these devices can be more powerful than a Pi and also be found for a much lower price.

He’s using one of these to run RetroPie, which actually turned out to be much easier than installing a more general-purpose Linux distribution and then running various emulation software piecemeal. It will take some configuration tinkering get everything working properly but with [Timax] providing this documentation it should be a lot easier to find compatible hardware and choose working software from the get-go. He also made some improvements on his hardware to improve cooling, but for older emulation this might not be strictly necessary. As he notes in his video, it’s a great way of making use of a piece of electronics which might otherwise be simply thrown out.

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What Next For The SBC That Has Everything?

In the decade-and-a-bit since the first Raspberry Pi was launched we’ve seen an explosion of affordable single-board computers (SBCs), but as the prices creep up alongside user expectation and bloat, [Christopher Barnatt] asks where the industry will go next.

The Pi started with an unbeatable offer, $35 got you something similar to the desktop PC you’d had a decade earlier — able to run a Linux desktop on your TV from an SD card. Over the years the boards have become faster and more numerous, but the prices for ARM boards are now only nominally as affordable as they were in 2012, and meanwhile the lower end of x86 computing is now firmly in the same space. He demonstrates how much slower the 2023 Raspberry Pi OS distribution is on an original Pi compared to one of the early pre-Raspbian distros, and identifies in that a gap forming between users. From that he sees those people wanting a desktop heading towards the x86 machines, and the bare-metal makers at the lower end heading for the more powerful microcontrollers which simply weren’t so available a decade ago.

We have to admit that we agree with him, as the days when a new Raspberry Pi board was a special step forward rather than just another fast SBC are now probably behind us. In that we think the Pi people are probably also looking beyond their flagship product, as the hugely successful lunches of the RP2040 and the industrial-focused Compute Module 4 have shown.

What do you think about the SBC market? Tell us in the comments.

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Laptop Motherboard? No, X86 Single-Board Computer!

Sometimes a Raspberry Pi will not cut it – especially nowadays, when the prices are high and the in-stock amounts are low. But if you look in your closet, you might find a decently-specced laptop with a broken screen or faulty hinges. Or perhaps someone you know is looking to get rid of a decent laptop with a shattered case. Electronics recycling or eBay, chances are you can score a laptop with at least some life left in it.

Let’s hack! I’d like to show you how a used laptop motherboard could be the heart of your project, and walk you through some specifics you will want to know.

And what a great deal it could be for your next project! Laptop motherboards can help bring a wide variety of your Linux- and Windows-powered projects to life, in a way that even NUCs and specialized SBCs often can’t do. They’re way cheaper, way more diverse, and basically omnipresent. The CPU can pack a punch, and as a rule PCIe, USB3, and SATA ports are easily accessible with no nonsense like USB-throttled Ethernet ports.

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Squeezing A Minimalist 6502 Retrocomputer Onto A Single Breadboard

Over the years, and especially lately, we’ve seen tons of single-board retrocomputer builds. That’s fine with us — the more, the merrier. But they all start to run together a bit, with little to distinguish between them. Not so this about-as-compact-as-possible 6502 computer that fits on a single breadboard.

Now, when you do the math, it seems like there’s no way that [Anders Nielsen] would have been able to fit even a minimal chipset onto a standard solderless breadboard. The 40-pin 6502 alone takes up nearly two-thirds of the connections available; add in equally large but necessary chips like the 6522 interface adapter, ROM and RAM chips, and some support ICs, and one breadboard isn’t going to cut it. Luckily, some frugal engineers at MOS back in the 70s came up with the 6507, a variant on the 6502 in a 28-pin DIP. The other key to this build is the 6532 RAM-I/O-timer chip or RIOT, which puts a tiny amount of RAM and some IO lines on a single 40-pin DIP. Along with a 28-pin ROM, a 14-pin hex inverter, and a little crystal oscillator, the entire chipset just barely fits on a single breadboard.

But what can this minimalist 6502 actually do? As you can see in the video below, anything a 555 timer can do, and maybe a little bit more. That’s not a dig, of course — [Anders] actually calls out his initial blinkenlight application as a little more than a glorified 555, and actually comes up with a marginally more complex application just to prove the point. The interesting part here is dealing with the constraints imposed by the limited resources available on this machine.

We’re looking forward to whatever comes next for this clever build. It’s hard to see how some of the plans [Anders] has for it will still fit on a single breadboard, though — these things tend to spread out as they go.

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