arm

386 Articles

Getting Started With Free ARM Cores On Xilinx

December 4, 2018 by 13 Comments

We reported earlier about Xilinx offering free-to-use ARM Cortex M1 and M3 cores. [Adam Taylor] posted his experiences getting things working and there’s also a video done by [Geek Til It Hertz] based on the material that you can see in the second video, below.

The post covers using the Arty A35T or Arty S50 FPGA boards (based on Artix FPGAs) and the Xilinx Vivado software. Although Vivado will allow you to do conventional FPGA development, it also can work to compose function blocks to produce CPUs and that’s really what’s going on here.

Continue reading “Getting Started With Free ARM Cores On Xilinx” →

Amazon Thinks ARM Is Bigger Than Your Phone

December 3, 2018 by 56 Comments

As far as computer architectures go, ARM doesn’t have anything to be ashamed of. Since nearly every mobile device on the planet is powered by some member of the reduced instruction set computer (RISC) family, there’s an excellent chance these words are currently making their way to your eyes courtesy of an ARM chip. A userbase of several billion is certainly nothing to sneeze at, and that’s before we even take into account the myriad of other devices which ARM processors find their way into: from kid’s toys to smart TVs.

ARM is also the de facto architecture for the single-board computers which have dominated the hacking and making scene for the last several years. Raspberry Pi, BeagleBone, ODROID, Tinker Board, etc. If it’s a small computer that runs Linux or Android, it will almost certainly be powered by some ARM variant; another market all but completely dominated.

It would be a fair to say that small devices, from set top boxes down to smartwatches, are today the domain of ARM processors. But if we’re talking about what one might consider “traditional” computers, such as desktops, laptops, or servers, ARM is essentially a non-starter. There are a handful of ARM Chromebooks on the market, but effectively everything else is running on x86 processors built by Intel or AMD. You can’t walk into a store and purchase an ARM desktop, and beyond the hackers who are using Raspberry Pis to host their personal sites, ARM servers are an exceptional rarity.

Or at least, they were until very recently. At the re:Invent 2018 conference, Amazon announced the immediate availability of their own internally developed ARM servers for their Amazon Web Services (AWS) customers. For many developers this will be the first time they’ve written code for a non-x86 processor, and while some growing pains are to be expected, the lower cost of the ARM instances compared to the standard x86 options seems likely to drive adoption. Will this be the push ARM needs to finally break into the server and potentially even desktop markets? Let’s take a look at what ARM is up against.

Continue reading “Amazon Thinks ARM Is Bigger Than Your Phone” →

Creating Black Holes: Division By Zero In Practice

November 21, 2018 by 31 Comments

Dividing by zero — the fundamental no-can-do of arithmetic. It is somewhat surrounded by mystery, and is a constant source for internet humor, whether it involves exploding microcontrollers, the collapse of the universe, or crashing your own world by having Siri tell you that you have no friends.

It’s also one of the few things gcc will warn you about by default, which caused a rather vivid discussion with interesting insights when I recently wrote about compiler warnings. And if you’re running a modern operating system, it might even send you a signal that something’s gone wrong and let you handle it in your code. Dividing by zero is more than theoretical, and serves as a great introduction to signals, so let’s have a closer look at it.

Chances are, the first time you heard about division itself back in elementary school, it was taught that dividing by zero is strictly forbidden — and obviously you didn’t want your teacher call the cops on you, so you obeyed and refrained from it. But as with many other things in life, the older you get, the less restrictive they become, and dividing by zero eventually turned from forbidden into simply being impossible and yielding an undefined result.

And indeed, if a = b/0, it would mean in reverse that a×0 = b. If b itself was zero, the equation would be true for every single number there is, making it impossible to define a concrete value for a. And if b was any other value, no single value multiplied by zero could result in anything non-zero. Once we move into the realms of calculus, we will learn that infinity appears to be the answer, but that’s in the end just replacing one abstract, mind-boggling concept with another one. And it won’t answer one question: how does all this play out in a processor? Continue reading “Creating Black Holes: Division By Zero In Practice” →

Smooth Moves From Cheap Motors

November 16, 2018 by 36 Comments

Building an electric motor isn’t hard or technically challenging, but these motors have very little in the way of control. A stepper motor is usually employed in applications that need precision, but adding this feature to a motor adds complexity and therefore cost. There is a small $3 stepper motor available, but the downside to this motor is that it’s not exactly the Cadillac of motors, nor was it intended to be. With some coaxing, though, [T-Kuhn] was able to get a lot out of this small, cheap motor.

To test out the motors, [T-Kuhn] built a small robotic arm. He began by programming his own pulse generating algorithm that mimics a sine wave in order to smooth out the movement of the motor. An Arduino isn’t fast enough to do these computations, though, so he upgraded to using the ESP32. He also was able to implement the inverse kinematics on his own. The result of all this work for a specific platform and motor type is a robotic arm that has a very low cost but delivers performance of much more expensive hardware.

The robot arm was built by [T-Kuhn] too, and all of the details on that build, as well as all the schematics and code, are available on the project site if you need a low-cost robot arm or a good stepper motor controller for a low cost. There are many other ways of getting the most out of other types of low-cost motors as well.

Continue reading “Smooth Moves From Cheap Motors” →

Short Length Of Wire Turns STM32 Microcontroller Into Good-enough Wireless UART Blaster

October 29, 2018 by 22 Comments

Hackaday regular [befinitiv] wrote into the tip line to let us know about a hack you might enjoy, wireless UART output from a bare STM32 microcontroller. Desiring the full printf debugging experience, but constrained both by available space and expense, [befinitiv] was inspired to improvise by a similar hack that used the STM32 to send Morse code over standard FM frequencies.

In this case, [befinitiv]’s solution is both more useful and slightly more legal, as the software uses the 27 MHz ISM band to blast out ASK modulated serial data through a simple wire antenna attached to one of the microcontroller’s pins. The broadcast can then be picked up by an RTL-SDR receiver and interpreted back into a stream of data by GNU Radio.

The software for the STM32 and the GNU Radio Companion graph are both available on Bitbucket. The blog post goes into some detail explaining how the transmitter works and what all the GNU Radio components are doing to claw the serial data back from the ether.

[cover image cc by-sa licensed by Adam Greig, randomskk on Flickr]

A New Kid On The Mini ARM Block

October 11, 2018 by 30 Comments

The breadboard microcontroller experimenter has a host of platforms to work with that can be had in the familiar DIP format. Old-school people can still find classic 8-bit platforms, the Ardunisti have their ATMegas, and PIC lovers have a pile of chips to choose from. But ARM experimenters? Out of luck, because as we have previously reported, popular past devices such as the LPC810 in a DIP8 package are now out of production.

News comes from China though of a tiny ARM Cortex M0 for pennies that may not be in a DIP8, but is in almost the next best thing. The Synwit SWM050 can be had in a TSOP8, which though it’s not quite as friendly as its larger SOIC8 cousin, is still easily solderable onto a DIP8 adaptor for breadboard use. Spec-wise it’s 5 V tolerant, has an 8 kB FLASH and 1 kB of RAM, 6 GPIOs, and can clock away at a not incosequential 36 MHz.

We have [Sjaak] to thank for the discovery of this device, and for doing a lot of work including getting some die shots taken to dig up and make sense of the Chinese documentation, and to provide some dev tools should anyone want to play with it.  There’s even a small breakout board for the experimenter unwilling to design their own.

Earlier this year we marked the passing of the DIP8 version of the LPC810 microcontroller, and for those mourning it we made an important point. It’s now normal to use one of the vast array of single board computers instead of a bare microcontroller, you might wish to ask yourself why you would do so.

Thanks [Ziew] for the tip.

Free ARM Cores For Xilinx FPGAs

October 2, 2018 by 30 Comments

In a surprising move, ARM has made two Cortex-M cores available for FPGA development at no cost.

In the over three decades since [Sophie Wilson] created the first ARM processor design for the Acorn Archimedes home computer, the architecture has been managed commercially such that it has become one of the most widely adopted on the planet. From tiny embedded microcontrollers in domestic appliances to super-powerful 64-bit multi-core behemoths in high-end mobile phones, it’s certain you’ll own quite a few ARM processors even if you don’t realise it. Yet none of those processors will have been made by ARM, instead the Cambridge-based company will have licenced the intellectual property of their cores to another semiconductor company who will manufacture the device around it to their specification. ARM core licences cost telephone-number sums, so unless you are a well-financed semiconductor company, until now you probably need not apply.

You will still have to shell out the dough to get your hands on a core for powerful chips like those smartphone behemoths, but if your tastes are more modest and run only to a Cortex M1 or M3 you might be in luck. For developers on Xilinx FPGAs they have extended the offer of those two processor cores at zero cost through their DesignStart Programme.

It’s free-as-in-beer rather than something that will please open-source enthusiasts, But it’s certainly a fascinating development for experimenters who want to take ARM for a spin on their own gate array. Speculation is swirling that this is a response to RISC-V, but we suspect it may be more of a partial lifting of the skirts to entice newbie developers such as students or postgraduates. If you arrive in the world of work already used to working with ARM IP at the FPGA level then you are more likely to be on their side of the fence when those telephone-number deals come up.

Thanks [Rik] for the tip!