Wednesday, July 27, 2011

Ethernet Arduinos (and Compatibles)

Also on the spreadsheet, three boards with built-in ethernet:
  • There's finally an official Arduino Ethernet ($60), complete with RJ45 port. It has an FTDI cable header for programming (no USB), a microSD card slot for storage, and there's an optional PoE daughter card.
  • SparkFun also released an Arduino-compatible board with ethernet, the Ethernet Pro ($55), but without the SD card slot. It's less cluttered than the official board, hopefully the price will come down as more people build projects around them.
  • Additionally, the Freetronics EtherTen ($70) includes a microSD slot and (mini) USB interface.
All of these are compatible with an Arduino (or Arduino-compatible) board with the ethernet shield ($40) on top, but I wonder: will shields fit on any of these without hitting the magjack? Or do they use taller female pin sockets? They're also equivalent to an Arduino hooked up to a Wiznet W5100, eg. with a WIZ811MJ module ($20!). Too bad Adafruit doesn't sell the ethernet module breakout shield anymore, but at least the design files are still available.

Call me cheap, but these all seem overpriced, being based around a $4 microcontroller! With a basic Arduino board at $20 and WIZ811MJ module at $20, why isn't the SparkFun Ethernet Pro $40 or $45?

Tuesday, July 26, 2011

More 'duinos on the Spreadsheet

I've continued to add Arduino-compatible boards to the spreadsheet, bringing the count to 119 boards. You can get there easily by remembering "allarduinos" and going to or

Some recent additions to the spreadsheet:

Monday, July 25, 2011

(F)Light Suit Progress: PWM!

I had a frustrating time trying to get a PCA9685 working-- it wouldn't even reply with its register byte values. I've interfaced with other I2C chips and didn't expect problems, but trouble was all I got.

Poking around the Arduino Forum trying to find any examples with a PCA9685, I found the thread on Elco Jacobs' new ShiftPWM library to drive the outputs of the ubiquitous 74HC595 shift register with 8-bit PWM precision. His demo video is on the right. The example sketch was so straightforward, I had two chips driving-- and dimming-- 16 red LED's in minutes.

Once I saw those red LED's cycling, I considered that part of the project done-- thank you, Elco!-- and started laying out a driver board with a 74HC595, eight outputs hooked up to MOSFETs and test LED's, and screw terminals so they can be daisy chained. With the DorkbotPDX order deadline this morning, I had to stay up late laying it out and getting a final Eagle brd file ready, and hopefully it will work; I wasn't that excited about asking for six copies of a 3.9"x2.1" V001 design and having no time for a second run if they don't work, but... hey, they'll work!

Here's the Eagle schematic: pdf, sch. And the board: pdf, brd.

Sunday, July 17, 2011

LED (F)Light Suit: Ramping Up

I've been mesmerized by bouncing red LED's since the early '80s. LED's were mostly red, needle-style VU meters were on the outs, we hadn't yet graduated to green-yellow-red meters, and I grew a special place in my heart for those bouncing red lights. We also had KITT and the Cylons: bouncing red lights were and still are awesome ("rad" had not been invented yet).

I put together a black flight suit with red EL-wire segments for Burning Man in 2008 but did not have time to build the sequencer and control system I envisioned, so it was an on/off affair, or it pulsated to the music before the small batteries died.

Working on a suit for this year's burn, I've decided to return to the original concept-- red LED's-- and am working on the major areas now:
  • Suit electronics: Arduino core, I2C port expander w/PWM output using PCA9685 16-channel, 12-bit PWM I2C-bus LED controller driving power MOSFETs, one per segment. There are 17 segments in my design, so I'll use the port expander and then another spare pin to trigger the 17th channel.
  • Audio metering: I have a MaceTech Shifty VU shield working but I wonder about adjusting levels on the fly, and how to best get a mic input to it or something similar. There will be other modes for sequencing the lights, but bouncing VU meter is the primary mode I'm looking for.
  • Segment planning: location and length of each segment, power lead routing, attachment to suit. This is going well, with the first seven (of 22) segments cut and tested last night from my first 5M strip from DealExtreme; the suit will need 53' of light strip so I've ordered more.
  • Power: rechargable 12V power packs are easy to get; not sure how to recharge them on the Playa.
  • Remote control: would like to have a small, wireless remote to control modes and mode parameters.
  • The program: I have a list of modes I'd like to switch between, some of which have parameters I'll want to adjust on the fly. Ideally I'll be able to edit the program during the day if I come up with new ideas while I'm in BRC.

Saturday, July 16, 2011

What is "Minimalduino"?

I started working on the "minimalduino" design as...
  1. a minimal hardware design for an Arduino-compatible board. At heart, it is very similar to the Dorkboard, but
  2. designed to match the form factor of the "official" Arduino boards so users can benefit from the many, many shield boards designed to fit on top. While (awesome) boards like EMSL's Diavolino are also low-cost and shield-friendly, I wanted to explore
  3. optional hardware configurations, with different power connector options (pin headers, JST connector, barrel jack, screw terminals, or mini USB jack), 5V and 3.3V power regulation and optional voltage switching and regulator bypassing, and options for crystal and caps or a resonator. I also wanted to have
  4. better shield-friendliness by placing LEDs (power and D13) and the reset switch (side switch or top switch) at the edges of the board, and lastly, I wanted the board to be
  5. single-sided, home-etchable with wide traces and minimal jumper wires. There is still work to be done to reduce jumpers, but it improves on the the S3V3 "Severino" board which doesn't match up size-wise (it's bigger), the standoff mounts don't match, and it uses a DB9 serial connector instead of the now widespread FTDI USB-serial breakout cable.