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Paul Gallagher

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My occasional technical diary of thoughts, tips, and tools from some of the more interesting things I'm playing around with at the time. That means all things Cloud, Open Source, Rails, BigData, Mobile, or just my latest rant.. who knows!
Updated: 11 hours 20 min ago

LittleArduinoProjects#018 The Fretboard - a multi-project build status monitor

Sun, 2016-02-07 10:13
(blogarhythm ~ Diablo - Don't Fret)

The Fretboard is a pretty simple Arduino project that visualizes the build status of up to 24 projects with an addressable LED array. The latest incarnation of the project is housed in an old classical guitar … hence the name ;-)

All the code and design details for The Fretboard are open-source and available at fretboard.tardate.com. Feel free to fork or borrow any ideas for your own build. If you build anything similar, I'd love to hear about it.

LittleArduinoProjects#100 Retrogaming on an Arduino/OLED "console"

Sun, 2016-02-07 10:12
(blogarhythm ~ invaders must die - The Prodigy)
Tiny 128x64 monochrome OLED screens are cheap and easy to come by, and quite popular for adding visual display to a microcontroller project.

My first experiments in driving them with raw SPI commands had me feeling distinctly old school, as the last time remember programming a bitmap screen display was probably about 30 years ago!

So while in a retro mood, what better than to attempt an arcade classic? At first I wasn't sure it was going to be possible to make a playable game due to the limited Arduino memory and relative slow screen communication protocol.

But after a few tweaks of the low-level SPI implementation, I was surprised myself at how well it can run. Even had enough clock cycles left to throw in a sound track and effects.

Here's a quick video on YouTube of the latest version. ArdWinVaders! .. in full lo-rez monochrome glory, packed into 14kb and speeding along at 8MHz.



Full source and schematics are in the LittleArduinoProjects collection on Github.

LittleArduinoProjects#174 USB LED Notifiers

Sun, 2016-02-07 10:05
So four of these USB Webmail Notifier devices turned up in a dusty cupboard
in the office.

A quick tear-down shows they contain a super-simple circuit - just a
SONiX Technology SN8P2203SB 8-Bit microcontroller that handles the USB protocol and drives an RGB LED. The SN8P2203SB is an old chip phased out 2010/04/30, superseded by the SN8P2240. They have a supremely primitive USB implementation - basically mimicking a very basic USB 1.0 HID device.

A quick google reveals quite a bit of old code lying around for various projects using devices like this. Most seem to use libusb for convenience - and often 0.1 legacy libusb that. As I'm mainly on MacOSX, the code is not much use since Apple no longer allows claiming of HID devices
and the libusb team decided not to try to get around that.

So to bring things up-to-date, I wrote a simple demo using hidapi
and things all work fine - see the video below.

Now I just need to ponder on good ideas for what to do with these things!

As always, all notes and code are on GitHub.

LittleArduinoProjects#173 Mini 64-LED Cube

Sat, 2016-02-06 21:53
LED cubes were a "thing" a few years back maybe ... but I've never built one. Time to fix that...

Here's my "mini" 4x4x4 cube - 3cm per side with 3mm clear blue LEDs. Pretty compact, and delivers nice effects. The clear blue LEDs work really well - very bright, even when driven with minimal current.

It's encased in a Ferrero Rocher cube box. During the build, that raised some challenges - most of the effort in building the project concerned squeezing all the electronics into the space in the lid (which becomes the base of the cube). Not quite as small as HariFun's "World's Tiniest RGB LED Cube" but about as small as you can get without resorting to SMD LEDs!

All notes, schematics and code are on GitHub as usual. Here's a quick demo: