The Catweazle Mini: A Super Small ARM Based Embedded Platform


There has been a recent trend in miniaturizing embedded platforms. [Jan] wrote in to tell us about his very tiny ARM based embedded platform, the Catweazle Mini. Who knew that an ARM based system could be so simple and so small?!?

With the success of the Trinket and Femtoduino (miniature Arduino compatible boards) and many other KickStarter campaigns, it is only natural for there to be a mini platform based on the ARM architecture. Built around the NXP LPC810 ARM Cortex M0+ MCU at 30MHz (which only costs slightly more than $1, by the way), this small embedded platform packs some pretty impressive processing power. The board contains a simple linear regulator, and can be programmed via UART. [Jan's] development environment of choice is the mbed compiler, which is free and requires no installation. If you need some help getting started Adafruit has a nice guide for the LPC810.

Do you need some more processing power for your next wearable project? Be sure to use the Catweazle Mini.

Hackaday Links: February 23, 2014


You can pick up a tiny laser pointer on the cheap if you know where to look. But when it comes time to replace the multiple button cells that power it be prepared to clean our your wallet. [KB3WZZ] got around that with the cap from a ball-point pen. He drilled holes in the end plug of the pointer, and used wire and a plastic pen cap as a battery adapter. He’s powering it from USB, but now that you have wires exiting the case you can use any source you wish.

[Gerben] tipped us off about the trinket clone he built himself. It’s a tiny sliver of a PCB which he etched, populated with through-hole parts only, and finished off with some finger nail varnish to prevent shorting and corrosion. The solder-covered edge connector for USB was left unvarnished of course.

If you live in a college town you are probably quite used to seeing futon pads and frames on the curb waiting for the garbage collector. A little bit of ingenuity, and some added lumber, will turn a futon frame into a respectable shelving unit. [Thanks Martin]

Complicated bench equipment + good lighting + a great camera = an awesome teardown. This time around it’s the guts of a Keithly 2002 8.5 digit mulitimeter laid bare. [Thanks David]

Here’s a PCB laminator hack that is definitely worth a look. The original unit was acquired on eBay for about $25 and had a thermostat whose performance wasn’t optimal. A bit of alteration for the thickness of the substrate, and you’ll never hand iron a toner transfer board again! [Thanks William]

Last summer we heard about Scout, an ocean-going drone trying to cross the Atlantic. We just checked the live tracking and the craft is still at sea. But a much smaller 5ft vessel made it from New Jersey to Guernsey (an island between the UK and France) after traveling for about 14 months. [Thanks Rob]

Valentine’s PCBs To Make Your Heart Melt


Have you ever sat in bed, staring at a bottle of Iron III Chloride, and thought “I should do something with that…”? [Tobias] has. He wanted to use his tinkering skills to make his girlfriend happy, so he decided to make this beautiful etched PCB that professes his love to her.

The cool thing about this project is that [Tobias] has never etched a PCB, or even worked with SMD parts before! After designing the PCB layout on his computer, he printed it out on an inkjet transparency film and applied it to his PCB. After 14 minutes of exposure he then put the board into development fluid for about 60 seconds — it was starting to look good already! He then pulled out his trusty bottle of Iron III Chloride and began the etching process.

Once the board was etched, he soldered 18 red PLCC-2 LEDs in place, each with its own 330Ohm resistor. Not content with a simple on/off switch, [Tobias] decided to program a Trinket with a voltage regulator and mosfet to have it pulse on and off, similar to a beating heart! The finished project looks great, and we’re sure his girlfriend will love it.

Another bonus to doing something geeky like this for your loved ones means it will increase their acceptance of tools laying about, and half-finished projects that aren’t quite as pretty!

Shrinket, The Homebrew Trinket


We’ve seen a lot of Trinket builds over the past few months, but so far few people have capitalized on the Trinket’s minimalism. It’s a fairly simple circuit, as far as dev boards go, and with careful planning can be built entirely on perfboard. That’s what [villeki] did, with a project he calls Shrinket.

After looking at the schematic for the Trinket, [villeki] figured he could best the very small footprint of this ATtiny85 board. To do this, he mounted the uC on the bottom side of the board, bending the pins so they could be easily soldered to the pins. The only real challenge in building this tiny board was the USB connector. To fit this connector on board, the copper pads were carefully scraped off the protoboard and wires run to the zeniers.

The Shrinket is impressively small – only 0.6″x 0.9″ – and a very impressive example of soldering skills. If you’re looking for a project to hone your free-form soldering skills, this is a great way to spend an hour or two. Bonus, you probably already have the parts required (or a reasonable substitute) sitting around.

Body of a Trinket, Soul of a Digispark


Adafruit’s Trinket and digiStump’s Digispark board are rather close cousins. Both use an ATtiny85 microcontroller, both have USB functionality, and both play nice with the Arduino IDE. [Ray] is a fan of both boards, but he likes the Trinket hardware a bit better. He also prefers the Digispark libraries and ecosystem. As such, he did the only logical thing: he turned his Trinket into a Digispark. Step 1 was to get rid of that pesky reset button. Trinket uses Pin 1/PB5 for reset, while Digispark retains it as an I/O pin. [Ray] removed and gutted the reset button, but elected to leave its metal shell on the board.

The next step was where things can get a bit dicey: flashing the Trinket with the Digispark firmware and fuses. [Ray] is quick to note that once flashed to Digispark firmware, the Trinket can’t restore itself back to stock. A high voltage programmer (aka device programmer) will be needed. The flashing process itself is quite a bit easier than a standard Trinket firmware flash. [Ray] uses the firmware upload tool from the Micronucleus project. Micronucleus has a 60 second polling period, which any Trinket veteran will tell you is a wonderful thing. No more pressing the button and hoping you start the download before everything times out! Once the Trinket is running Digispark firmware, it’s now open to a whole new set of libraries and software.

Cloning the Trinket for a USB Volume Knob


A while back, [Rupert] wrote a blog post on using V-USB with the very small, 8-pin ATtiny85. Since then, the space of dev boards for 8-pin micros with USB has exploded, the most recent being Adafruit’s Trinket. [Rupert] liked what he saw with the Trinket bootloader and decided to clone the circuit into a useful package. Thus was born an awesome looking USB volume knob complete with a heavy aluminum knob, rotary encoder, and RGB LED strip.

[Rupert] got his V-USB/ATtiny85/rotary encoder circuit working, and at the expense of a ‘mute’ control, also added an awesome looking RGB LED ring powered by Adafruit’s Neopixels. The PCB [Rupert] fabbed is pretty well suited for being manufactured one-sided. If you’ve ever wanted an awesome volume knob for your computer, all the files are available form [Rupert]‘s blog.

Just as an aside, [Rupert] has been working on getting the Trinket bootloader working on the ATtiny84, a very similar microcontroller to the ’85, but with eight analog pins. It’s a neat device that I’ve made a small V-USB breakout board for, but like [Rupert], I’m stuck on porting the bootloader. If anyone has the Trinket/Gemma firmware running on an ATtiny84, send that in. We’ll put it up.