ARM

Library upgrade to PRU gives Fast IO on Beaglebone

February 16, 2015 by 18 Comments

The BeagleBone Black has a powerful featureset: decent clock speed, analog inputs, multiple UART, SPI and I2C channels and on-board memory, to name a few. One missing feature seems to be the lack of support for the two on-board Programmable Real-time Units (PRU’s). Each of these 32-bit processors run independently of the main processor, but are able to interface with the main processor through the use of shared RAM and some interrupts. Unfortunately, PRU’s are not supported and in the absence of information, difficult to program. Enabling the PRU’s will allow them direct access to external sensors via the GPIO pins, for example. Perhaps most enticing is the idea that the PRU’s add real-time processing capability to the BBB.

[Thomas Freiherr] is working on the libpruio project to allow PRU support on the BBB. It is “designed for easy configuration and data handling at high speed. libpruio software runs on the host (ARM) and in parallel on a Programmable Realtime Unit SubSystem (= PRUSS or just PRU) and controls the subsystems”. Additional information about the project is available on the libpruio wiki, and files can be downloaded from here (German Page).

This paper presented at inter.noise2014 (PDF) a couple of months ago has a nice comparison of various small computer/controller boards and outlines the advantages of the BBB once its PRUs are enabled. If readers come across applications of the BBB with PRUs enabled, let us know in the comments. If you want to work your way into the world of the PRU we highly recommend this tutorial series.

Thanks for sending in the tip, [Patrick]

[Image Source: libpruio stepper motor example]

The Teensy LC. LC Means Low Cost.

February 3, 2015 by 47 Comments

For one reason or another, we’ve been seeing a lot of builds featuring the Teensy 3.1 filtering in on the tip line recently. In retrospect, it’s somewhat obvious; it’s a good board that’s cheap and fast. Yes, somehow [Paul] hit all three in the good/cheap/fast mutually exclusive triumvirate.

Now, there’s a new Teensy. It’s the Teensy LC – Low Cost. It’s not as powerful as the Teensy 3.1, but it does give you the power of an ARM for something that’s just about as cheap as a board with an ATMega.

The chip [Paul] chose for the Teensy LC is the Freescale MKL26Z64 (datasheet here and 876-page reference manual here. PDFs of course). This is a 32-bit Cortex-M0+ running at 48 MHz with 64k of Flash and 8k of RAM. There are 27 digital I/O pins on this one, and the Teensy LC has been designed to be pin-compatible with the Teensy 3.0 and 3.1.

On board are 13 analog inputs, 8 PWM outputs, on 12-bit DAC output, three serial ports, two SPI ports, and two I2C ports. Most of the pins can drive 5mA with a few capable of driving 20mA, and there is a single 5v output pin for driving WS2812 Neopixel LEDs.

Since this is a cut-down version of the Teensy, everything available on the Teensy 3.1 just can’t fit into the BOM of the Teensy LC. The pins aren’t 5V tolerant, there’s no CAN bus, and there are only 4 DMA channels instead of 16 on the Teensy 3.1. Still, it’s a great ARM answer to the ATMega Trinket or other small dev boards.

Passion Project Turns BeagleBone into Standalone Super NES

January 31, 2015 by 16 Comments

So you want to play some retro games on your BeagleBone, just load up Linux and start your favorite emulator right? Not if you’re serious about it. [Andrew Henderson] started down this path with the BeagleBoard-xM (predecessor of the BeagleBone Black) and discovered that the performance with Snes9X wasn’t quite what he had in mind. He got the itch and created a full-blown distro called BeagleSNES which includes bootloader and kernel hacks for better peformance, a custom GUI, and is in the process of developing hardware for the embedded gaming rig. Check out the documentation that goes along with the project (PDF); it’s a blueprint for how open source project guides should be presented!

The hardware he’s currently working on is a Cape (what add-on boards for the BBB are called) that adds connectors for original Nintendo and Super Nintendo controllers. It also includes an RTC which will stand in for the real-time clock features included in some cartridges (Pokemon Yellow). Also in the works is a 3D printed enclosure which would turn it into a portable, something like this other BBB portable hack.

Check out a demo of what BeagleSNES can do in the video after the break.

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Casing up the Teensy SDR

January 30, 2015 by No comments

[Rich, VE3MKC] has made a lot of progress on his Software Defined Radio (SDR) which is based on a Teensy. His latest update shows off the hardware in an enclosure and a few new features.

When we looked at this in April of last year it was pretty much a proof-of-concept with components hanging loose from jumper wires. The new case mounts everything securely in a plastic Hammond enclosure with copper clad for the front and rear panels. The SoftRock SDR unit was yanked from its case and retrofitted with connectors to make it swappable for other units.

A little help goes a long way and [Rich] thanks his friend [Loftur, VE2LJX] for contributing numerous code improvements and feature additions which can be viewed in the repository. Check out the video below where these features are shown off.

In its present state the radio draws 80 mA at 12V in receive mode. It doesn’t transmit yet but we’ll keep our eyes open for another update on that. [Rich] plans to populate the input circuitry and write the transmit code next.

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ARM Pro Mini

January 19, 2015 by 83 Comments

Slowly but surely, the age of 8-bit micros being the first tool anyone picks up is coming to an end, and we’re seeing more and more ARM dev boards in nifty, breadboard-friendly packages. [Zapta] thought he would throw his hat into the ring with the ARM Pro Mini, a tiny little board based on the ARM M0 microcontroller.

The ARM chip on this board is the NXP LPC11 with 64 kB of Flash, 12 kB of RAM, and just enough pins to make the whole endeavor worthwhile. The board itself is extremely simple, with just enough SMD parts to be annoying to hand solder.

All the nifty bonuses of ARM boards are available on the ARM Pro Mini, including drag and drop firmware over the USB port, support for single stepping and debugging, and the IDE is a single install with NXP Eclipse/LPCXpresso. Mbed is also supported, so it’s possible to use this board with no software installs when using the online Mbed IDE.

[Zapta] has put everything you need to build this board up on his Github, and has even done a few simple ‘getting started’ tutorials, including a cool little example with a graphics library and a small OLED.

ZX81 Emulated on an mbed

December 22, 2014 by 7 Comments

This is a wonderful example of the phenomenon of “feature creep”. [Gert] was working on getting a VGA output running on an mbed platform without using (hardly) any discrete components. Using only a few resistors, the mbed was connected to a VGA display running at 640×480. But what could he do with something with VGA out? He decided to emulate an entire Sinclair ZX81 computer, of course.

With more than 1.5 million units sold, the Sinclair ZX81 was a fairly popular computer in the early ’80s. It was [Gert]’s first computer, so it was a natural choice for him to try to emulate. Another reason for the choice was that his mbed-VGA device could only output monochrome color, which was another characteristic of the ZX81.

[Gert] started by modifying a very lean Z80 emulator to make the compiled code run as efficiently as possible on the mbed. Then he went about getting a picture to display on the screen, then he interfaced an SD card and a keyboard to his new machine. To be true to the original, he built everything into an original ZX81 case.

This isn’t the first time we’ve seen a ZX81, but it is one of the better implementations of an emulated version of this system we’ve seen.

Thanks to [Jeroen] for the tip!

Towards More Interesting Instant Cameras

December 18, 2014 by 22 Comments

When [Ch00f] was getting jeans rung up at Nordstroms, he noticed how fast thermal receipt printers can put an image on a piece of paper. This observation isn’t unique to the circles [Ch00f] frequents – there are a few small receipt paper printers out there that connect to the Internet, iPhones, and a whole bunch of other Kickstarter-friendly keyword devices.

Nevertheless, a device that can make a hard copy of an image quickly and cheaply isn’t something you just stop thinking about. After rolling the concept around in his head for a few years, [Ch00f] finally came up with the perfect build – a camera.

The hardware for the build is based around an STM32F4 Discovery board. It’s a bit overpowered for this sort of application, and this is one of [Ch00f]’s first adventures in ARM-land. The rest of the hardware consists of a thermal receipt printer and a JPEG camera, the latter of which replaced a cellphone CMOS camera module that was lost in a move.

A custom camera requires a custom enclosure, and for this [Ch00f] made something remarkable. The entire enclosure is CNC milled out of a beautiful piece of figured walnut. The end result looks far too good for a prototype, but it does polish up nicely with a bit of linseed oil.

Now [Ch00f] has an instant camera that takes the idea of a Polaroid and turns it into something that produces a print for tenths of a cent. There’s a time-lapse function – just a zip tie on the shutter button – filters with the help of highlighters, and the ability to record movies in flipbook format.

It’s a great project, and also something that will make for a great crowdfunding campaign. [Ch00f] has already started work on this. He already has a sleek, modern-looking website that requires far too much scrolling than should be necessary – the first step to a winning Kickstarter. [Ch00f] also learned a lot about ARMs, DMA, dithering, gamma correction, and the JPEG format, but that’s not going to get anyone to open up their wallet. You know what will? A slick video. You’ll find that below.

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