Debug ARM Virtually

April 23, 2021 by Al Williams 8 Comments

With the advent of super powerful desktop computers, many developers make use of some sort of virtual or psuedo-virtual machines (VM). We run Windows in a VM and do kernel development in a VM, too. If you are emulating the same kind of computer you are on then the process is simpler, but it is possible to run, say, ARM code on an x86 (or vice versa) but with possibly slower performance than running natively. QEMU is probably the best-known program that allows a CPU to run code targeting a different CPU, but — by default — it targets desktop, laptop, and server-class machines, not tiny embedded boards. That’s where xPack QEMU Arm comes in. It allows you to run and debug embedded Cortex-M devices in an emulated environment on a host computer.

The tool supports boards like the Maple — which means it should support bluepill, along with popular boards such as the Nucleo, some discovery boards, and several from Olimex. They have plans to support several popular boards from TI, Freescale, and others, but no word on when that will happen. You can see a decidedly simple video example from [EmbeddedCraft] of blinking a virtual LED in the video below, although you might like to mute your audio before playing it.

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Bare-Metal STM32: Please Mind The Interrupt Event

March 26, 2021 by Maya Posch 27 Comments

Interruptions aren’t just a staple of our daily lives. They’re also crucial for making computer systems work as well as they do, as they allow for a system to immediately respond to an event. While on desktop computers these interrupts are less prominent than back when we still had to manually set the IRQ for a new piece of hardware using toggle switches on an ISA card, IRQs along with DMA (direct memory access) transfers are still what makes a system appear zippy to a user if used properly.

On microcontroller systems like the STM32, interrupts are even more important, as this is what allows an MCU to respond in hard real-time to an (external) event. Especially in something like an industrial process or in a modern car, there are many events that simply cannot be processed whenever the processor gets around to polling a register. Beyond this, interrupts along with interrupt handlers provide for a convenient way to respond to both external and internal events.

In this article we will take a look at what it takes to set up interrupt handlers on GPIO inputs, using a practical example involving a rotary incremental encoder.

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The Long Journey Ahead For Linux On Apple Silicon

March 21, 2021 by Bryan Cockfield 41 Comments

An old joke from the Linux community about its prevalence in computing quips that Linux will run on anything, including some animals. While the joke is a little dated, it is true that Linux can run on just about any computing platform with a certain amount of elbow grease. The current exception is the new Apple M1 silicon, although one group called Asahi Linux is currently working to get Linux running on this novel hardware as well.

While the Apple M1 is specifically built to run macOS, there’s no technical reason why Linux couldn’t run on it once all of the kinks are ironed out. This progress report from last month outlines some of the current areas of focus, especially around booting non-Mac kernels. The new Apple silicon runs on an ARM processor and because of this it functions more like an embedded device than a PC with standardized BIOS or UEFI. This means a lot of workarounds to the proprietary boot process have to be created to get a Linux kernel to boot. Luckily there are already versions of Linux that run on ARM so a lot of work has already been done, but there’s still much ahead.

While it’s probably best to buy an x86 machine for the time being if you need a Linux on your own personal machine, it seems like only a matter of time until all of the barriers to Linux are overcome on the M1 silicon. If Linux is able to take advantage of some of the efficiency and performance benefits of these chips, it could be a game-changer in the Linux world and at least give us all another option for hardware. Of course, we will still be needing software that can run on ARM, too.

Thanks to [Mark] for the tip!

Blue Pill Vs Black Pill: Transitioning From STM32F103 To STM32F411

January 20, 2021 by Maya Posch 78 Comments

For many years now, the so-called ‘Blue Pill’ STM32 MCU development board has been a staple in the hobbyist community. Finding its origins as an apparent Maple Mini clone, the diminutive board is easily to use in breadboard projects thanks to its dual rows of 0.1″ pin sockets. Best of all, it only costs a few bucks, even if you can only really buy it via sellers on AliExpress and EBay.

Starting last year, boards with a black soldermask and an STM32F4 Access (entry-level) series MCUs including the F401 and F411 began to appear. These boards with the nickname ‘Black Pill’ or ‘Black Pill 2’. F103 boards also existed with black soldermask for a while, so it’s confusing. The F4xx Black Pills are available via the same sources as the F103-based Blue Pill ones, for a similar price, but feature an MCU that’s considerably newer and more powerful. This raises the question of whether it makes sense at this point to switch to these new boards.

Our answer is yes, but it’s not entirely clearcut. The newer hardware is better for most purposes, really lacking only the F103’s dual ADCs. But hardware isn’t the only consideration; depending on one’s preferred framework, support may be lacking or incomplete. So let’s take a look at what it takes to switch. Continue reading “Blue Pill Vs Black Pill: Transitioning From STM32F103 To STM32F411” →

PET 2001 Emulator On $2 Of Hardware

December 9, 2020 by Bryan Cockfield 20 Comments

Since the late 60s, Moore’s law has predicted with precision that the number of semiconductors that will fit on a chip about doubles every two years. While this means more and more powerful computers, every year, it also means that old computers can be built on smaller and cheaper hardware. This project from [Bjoern] shows just how small, too, as he squeezes a PET 2001 onto the STM32 Blue Pill.

While the PET 2001 was an interesting computer built by Commodore this project wasn’t meant to be a faithful recreation, but rather to test the video output of the Blue Pill, with the PET emulation a secondary goal. It outputs a composite video signal which takes up a good bit of processing power, but the PET emulation still works, although it is slightly slow and isn’t optimized perfectly. [Bjoern] also wired up a working keyboard matrix as well although missed a few wire placements and made up for it in the software.

With his own home-brew software running on the $2 board, he has something interesting to display over his composite video output. While we can’t say we’d emulate an entire PC just to get experience with composite video, we’re happy to see someone did. If you’d like to see a more faithful recreation of this quirky piece of computing history, we’ve got that covered as well.

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DevTerm Beats Cyberdeck Builders To The Punch

December 8, 2020 by Tom Nardi 45 Comments

What makes a cyberdeck? Looking as though it came from an alternate reality version of the 1980s is a good start, but certainly isn’t required. If you’re really trying to adhere to the cyberpunk ethos, any good deck should be modular enough that it can be easily repaired and upgraded over time. In fact, if it’s not in a constant state of evolution and flux, you’ve probably done something wrong. If you can hit those goals and make it look retro-futuristic at the same time, even better.

Which is why the Clockwork DevTerm is such an interesting device. It ticks off nearly every box that the custom cyberdeck builds we’ve covered over the last couple years have, while at the same time being approachable enough for a more mainstream audience. You won’t need a 3D printer, soldering iron, or hot glue gun to build your own DevTerm. Of course if you do have those tools and the skills to put them to work, then this might be the ideal platform to build on.

With a 65% QWERTY keyboard and widescreen display, the DevTerm looks a lot like early portable computers such as the TRS-80 Model 100. But unlike the machines it draws inspiration from, the display is a 6.8 inch 1280 x 480 IPS panel, and there’s no pokey Intel 8085 chip inside. The $220 USD base model is powered by the Raspberry Pi Compute Module 3, and if you need a little more punch, there are a few higher priced options that slot in a more powerful custom module. Like the Waveshare Pi CM laptop we recently looked at, there’s sadly no support for the newer CM4; but at least the DevTerm is modular enough that it doesn’t seem out of the question that Clockwork could release a new mainboard down the line. Or perhaps somebody in the community will even do it for them.

Speaking of which, the board in the DevTerm has been designed in two pieces so that “EXT Module” side can be swapped out with custom hardware without compromising the core functionality of the system. The stock board comes with extra USB ports, a micro USB UART port for debugging, a CSI camera connector, and an interface for an included thermal printer that slots into a bay on the rear of the computer. Clockwork says they hope the community really runs wild with their own EXT boards, especially since the schematics and relevant design files for the entire system are all going to be put on GitHub and released under the GPL v3.

They say that anything that sounds too good to be true probably is, and if we’re honest, we’re getting a little of that from the DevTerm. An (CPU BLOBs aside!) open hardware portable Linux computer with this kind of modularity is basically a hacker’s dream come true, and thus far the only way to get one was to build it yourself. It’s hard to believe that Clockwork will be able to put something like this out for less than the cost of a cheap laptop without cutting some serious corners somewhere, but we’d absolutely love to be proven wrong when it’s released next year.

Hacking The FPGA Control Board From A Bitcoin Miner

November 18, 2020 by Tom Nardi 49 Comments

For anyone serious about mining cryptocurrency such as Bitcoin, we’re well past the point where a standard desktop computer is of much use. While an array of high-end GPUs is still viable for some currencies, the real heavy hitters are using custom mining hardware that makes use of application-specific integrated circuits (ASICs) to crunch the numbers. But eventually even the most powerful mining farm will start to show its age, and many end up selling on the second hand market for pennies on the dollar.

Naturally, hackers are hard at work trying to find alternate uses for these computational powerhouses. While it won’t teach an old ASIC a new trick, [xjtuecho] has documented some very interesting details on the FPGA control board of the Ebit E9+ Bitcoin miner. Known as the EBAZ4205, this board can be purchased for around $20 USD from online importers and even less if you can find one used. Since it’s just the controller it won’t help you build a budget super computer, but there’s always interest in cheap FPGA development boards.

The Zynq SoC combines an FPGA and ARM CPU.

According to [xjtuecho], it takes a little bit of work to get the EBAZ4205 ready for experimentation. For one thing, you may have to solder on your own micro SD slot depending on where you got the board from. You’ll also need to add a couple diodes to configure which storage device to boot from and to select where the board pulls power from.

Once you’re done, you’ll have a dual core Cortex A9 Linux board with 256 MB DDR3 and a Artix-7 FPGA featuring 28K logic elements to play with. Where you go from there is up to you.

This isn’t the first time we’ve seen FPGA boards hit the surplus market at rock bottom prices. When IT departments started dumping their stock of Pano Logic thin clients back in 2013, a whole community of dedicated FPGA hackers sprouted up around it. We’re not sure the if the EBAZ4205 will enjoy the same kind of popularity in its second life, but the price is certainly right.

[Thanks to Rog77 for the tip.]