todbot blog

ThingM at Maker Faire 2010

todbot — Sun, 30 May 2010 23:51:08 +0000

My company ThingM had an official presence at Maker Faire this year. We were showing off the BlinkM line, including the new BlinkM MinM and the LinkM USB BlinkM controller. It was a lot of fun. And packed!

(click any photo to go to larger version on Flickr)

We were in the Maker Shed building, right underneath the Arduino banner, so we got lots of awesome questions about Arduino. The most common: “So I just picked up this thing that says ‘works with Arduino’…well, what *is* Arduino?” It was so great to see so many people interested [...]

MobileMe Free: iPhone to iCal OTA syncing

todbot — Mon, 22 Mar 2010 07:05:19 +0000

I’ve been frustrated with my calendars not being in sync between my iPhone and my Mac’s iCal. I’ve inadvertently double-booked myself many times. I didn’t want to spend $99 a year for MobileMe because I already spent a lot on remote servers and don’t need most of what MobileMe offers. I just want calendar syncing. The below has been described by many others, in much greater detail and clarity. This is really a list of things I did so I can remember it.

The essential idea is both iCal and the iPhone Calendar program can talk [...]

BristleBots and LED throwie art at Crash Space!

todbot — Sun, 07 Mar 2010 22:45:39 +0000

This upcoming Tuesday, 9 March 2010, 8pm at Crash Space in Culver City, we’ll be having some fun quick DIY projects for you to build. Come on over and have fun with us. The project kits are $5 for CrashSpace members or $10 for non-members and you can take them home after you build them.

In the kit you get the parts to build your own Bristlebot, a tiny robot made from a toothbrush: (consists of toothbrush, pager motor, battery, and foam tape)

and LED throwie art: (consists of two color-changing RGB LEDs, battery, and a magnet)

We’ll have a Bristlebot [...]

Momentary Button as On/Off Toggle using 555

todbot — Sun, 03 Jan 2010 06:29:15 +0000

(as a few had noticed, I had an error in the schematic shown. It’s been updated, thanks!)

A recent question from a friend who made a really cool BlinkM hoodie was: How can you turn a momentary button press into an on/off toggle?

There are tons of ways to do this if you like getting into electronics. Most all work off of some flip-flop like principle. And while I could have suggested a true flip-flop chip, I thought it would be cooler if you could use a 555 timer chip (which contains a single flip-flop and a couple [...]

I2CScanner.pde: Arduino as I2C bus scanner

todbot — Sun, 29 Nov 2009 21:28:31 +0000

One of the challenges of working with I2C (aka “two-wire” or “TWI” or “Wire”) devices is knowing the I2C address of the device. Older devices have a fixed address, or a “choose one-of-four” approach. But newer I2C devices have fully programmable addresses, leading to cases of not knowing what address a device is at.

Fortunately, there’s a technique one can use to “scan” an I2C bus and determine these addresses. Conceptually it’s very similar to a network “ping”. Below is an Arduino sketch “I2CScanner.pde” that turns an Arduino into an I2C bus scanner.

- I2CScanner.pde — Turn Arduino into [...]

Too Much RFID

todbot — Thu, 19 Nov 2009 17:11:37 +0000

[This post was part of a CrashSpace mailing list discussion on a "proximity t-shirt": a shirt that would light up or similar when other similar t-shirts were nearby. People were wondering how good RFID was at localized detection of tags.]

Okay so I’m a big RFID nerd, did a lot of consulting work using it. So here’s a quick brain dump.

Regular passive RFID is designed for identification not localization. The RFID tags can be reliably read only to within a few centimeters. But the readers are cheap. You can get 128kHz (LF) and 13.56MHz (HF) RFID [...]

Scary Shifty Servo Eyeballs

todbot — Thu, 08 Oct 2009 03:18:42 +0000

If you want a slightly different look for your Halloween pumpkin or skull, you can pretty quickly whip something up with a few servos and an Arduino. Here’s a set of Scary Shifty Servo Eyeballs, for instance: It looks around randomly…what’s over there!… wait, what’s that!

As you can probably tell it’s a pretty simple arrangement (click for bigger):

Building It

It consists of the following components: - 2 toy eyeballs or ping pong balls painted like eyeballs - 2 small servos (HXT500 from HobbyKing.com or similar) - 1 standard servo - 1 Arduino with tiny breadboard rubber-banded on top - 2 BlinkMs, one for each [...]

Not a sunrise, but a galaxy rise

todbot — Fri, 25 Sep 2009 04:42:58 +0000

This is one of the greatest bits of youtubery I’ve ever seen, and I generally dislike auto-tuned stuff. Carl Sagan’s Cosmos was one of the most important things to happen to me as a child. This video & song gives me the shivvers. And makes me miss Sagan all the more.

I love the song’s chorus created from cut up Sagan quotes: A still more glorious dawn awaits Not a sunrise, but a galaxy rise A morning filled with 400 billion suns The rising of the milky way

(via jwz)

Behold the Crystal Monster

todbot — Tue, 22 Sep 2009 17:13:38 +0000

The Crystal Monster is an art piece created by Beverly Tang and Tod E. Kurt (me). It’s on display in the Continental Gallery on 4th & Spring St in downtown Los Angeles. The shape and structure of the Crystal Monster are Beverly’s design. I created the lighting and the electronics. It’s made from over 400 sheets of laser-cut acrylic, more that 240 feet of LED tape (>2200 RGB LEDs!), and around 500 steel rods and other steel hardware. It’s approximately 12 feet long and 10 feet wide and hovers 10 feet above your head. It’s [...]

Arduino Serial protocol design patterns

todbot — Fri, 31 Jul 2009 03:50:38 +0000

[I posted this to the Arduino developer's mailing list, but figured others might find it useful too]

When I first started with Arduino, I thought Serial.available() was a very loose wrapping of the RXC bit in the USCRA register, i.e. if I didn’t get data out of there fast, it’d be gone. That led to convoluted code like:

if( Serial.available() ) { val1 = Serial.read(); while( !Serial.available() ); val2 = Serial.read(); // and so on }

Yuck. So you end up designing protocols that are too terse. Or maybe you think you need to [...]

Quickie Laser-cut iPhone/iPod Dock

todbot — Thu, 16 Jul 2009 01:48:39 +0000

I recently got a case for my iPhone and it’s the kind that precludes the use of the dock. I kind of like the dock concept, but instead of taking a Dremel to the existing dock, I spent a few minutes drawing up a replacement that could be cut from acrylic scraps on the laser cutter. Here’s the result: (click for higher-res)

It is made of four slices of 1/4″ acrylic (actual width 0.22″). The top two slices have an oval opening just snug enough to fit the ipod connector and keep it in place with friction. [...]

Laser Cut Laptop Stand (and o’scope hugger)

todbot — Wed, 17 Jun 2009 06:55:02 +0000

I have one of those USB-based logic analyzers that needs Windows software to make it go. I had been doing Windows-in-a-window with VMWare, but it’s kind of a pain. If I were to use a real Windows laptop, I’d need a shelf or something for it. I wanted it above my oscilloscope, which meant a laptop stand that was taller and wider than most. Time for the laser cutter!

(click for larger)

My design requirements were: - assemble without any tooling or fasteners - fit on a single 1′x2′ sheet of the 1/4″ plywood I already had - be stable enough [...]

Minimal Arduino with ATmega8

todbot — Wed, 27 May 2009 00:36:37 +0000

Or: A good use for old Arduino boards

Like me, you may have a few old Arduino boards or ATmega8 chips (in the boards) laying around from when you were first playing with Arduino. Those chips can still be really useful as the heart of a tiny “Minimal Arduino” setup.

A normal Arduino board contains support components that make it easy to use. If you want a smaller footprint, you can get one of the many Arduino work-alike boards. But if you want a really small footprint, and reuse your old parts, you can make an Arduino board using [...]

Arduino chip sticker label

todbot — Sun, 24 May 2009 04:53:15 +0000

I’ve been working with a super minimal Arduino setup recently. After seeing Alex’s awesome Arduino/ATmega breadboard header, where he notes there’s no room on the PCB for pin labeling, I wondered if it would be possible to make a small sticker that goes on the ATmega chip, labeling the pin names.

Here’s my first attempt:

And in use:

This was created by printing on a full-page sticker then laser cutting it to shape. I could have also just cut out the sticker with scissors, or used regular printer paper and double-sided tape.

Some files if you want to try this out [...]

Using MaxM with flexible RGB tape

todbot — Thu, 21 May 2009 22:41:30 +0000

A single BlinkM MaxM can easily drive a 5 meter (16 ft) roll of the flexible RGB SMD LED tape that’s used for architectural lighting. Each roll contains 150 RGB LEDs.

Each LED in the tape is a SMD RGB "5050" LED, capable of putting out about 6000mcd. The spacing between LEDs is 3.3cm (~1.25").

Every 3 LEDs is a cut mark with solder tabs so you can cut or join pieces of tape.

Max current for a 5m roll is about 1.9 Amps. I did a quick test of MaxM driving three rolls at about 6A and [...]