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Motivation Vitamins: Maker Faire

400 total control lighting pixels!

Wow, have you guys ever been to the maker faire?! It is amazing! Highlights include stilting around with the Stilt Factory crew, watching the life size mousetrap, listening to Arduino founder Massimo Banzi talk about what Arduino's working on, and chatting it up with Cool Neon.

Stilt frame sketches

And check out the little self-Santa'd Christmas present I got from Cool Neon this week! Oh yeah. I've completed the design for my stilt frames (check it out below) and will be building them out over the long weekend. And these bad boys are gonna be set into the stilt frames about every inch and a half. Thing's gonna light up like Vegas!

bringing the beats

shot of the horribly messy
prototype hardware

Getting audio working on Lightwalker has been a huge pain. I played around with a few electret microphones (like this guy from sparkfun) and had some bad luck with getting it to do what I wanted. In fact, I couldn't get it to do anything worthwhile. I even went as far as switching to using my android phone as the microphone and sending volume commands to my arduino over bluetooth. Doing so requires you to calculate root mean square and count zero crossings and all sorts of audio processing that I haven't done before. Was really cool to play with and tweak. But, in the end, doing the calculations in software and sending over bluetooth turned out to be way too slow.

I ended up landing on using a spectrum shield from sparkun in conjunction with their electret micrphone breakout board. Thought the whole thing was shot when I got it. And then I realized their documentation is incorrect and you have to run the mic at 3.3v instead of 5v. Has been great since I switched it. I might end up switching to just using an MSGEQ7 instead of the entire shield, but this is fine for now.

Another challenge I ran into was trying to figure out how to make it deal with the quiet of deep playa and being on the edge of a major sound camp. Once again, moving averages to the rescue! By keeping a moving average, I can compare the current volume to the average and adjust what the peak is as I go. So, moving from a quiet environment to a loud one or vice-versa will allow the lights to react visually well in both settings.

Check out the video. The lights and music are a little more synchronized in real life, but you get a good idea.

Arm stilts. Engaged.

tall shadow walking

Took a break from the electronics today to turn the wooden crutches I found at the second hand store into arm stilts. Kinda nice to see that piece come together and be able to walk around on all four limbs three feet off of the ground.

The construction is super simple. I literally just unbolted the bottom of the wooden stilts and bolted in a five foot 2" x 2" with some homemade rubber feet on them. Spent about 30 minutes cruising around the park to check it all out. Overall I'm psyched. But, I'm definitely gonna have to put in some practice time as the arm stilts are fairly heavy and it's definitely a chore to keep them lifted most of the time. Will have to re-think whether or not wood's the right material for this.

bought crutches w/ custom stilt leg

multiplexing working!

The TCA9548A soldered onto a
Schmartboard w/ male pins

Surfing, scuba diving, swimming with turtles, and downing boat drinks in Hawaii must go a long way towards making one smart and productive cause I've only been back from Hawaii for 24 hours and I've already finished a book (Something Wicked This Way Comes), got 8 hours of sleep, worked for 8 hours, ate two tacos, and gotten my multiplexing chip working!

I posted a while back about getting the TCA9548A I2C multiplexing chip and the Schmartboard and just now finally got it all soldered up and tested it out. The soldering was ridiculously easy for a chip this size. Got to hand it to Schmartboard for finding a slick, easy to use design. Literally took me 10 minutes from start to finish including heating up the iron and soldering a test chip. In retrospect, I should have soldered female connections onto this board or even gotten the Schmartboard arduino shield, but I'm definitely a noob and this is what happens. It'll work for now.

The longest part of the whole ordeal was figuring out how to wire the thing up, but in the end, I got it all working and was even able to hookup two ADXL-345 accelerometers to it and get readings from both. Again, the main point of this chip is that I want to hook 4 accelerometers up to my board over I2C but all the accelerometers have the same I2C address hardcoded. So, with the TCA9548A, I can control which one I'm talking to at any point in time.

Here's the sample Arduino sketch I threw together to demo things:

#include <Wire.h>
#include <ADXL345.h>
#include <SPI.h>
#include <TCL.h>

#define TCA9548AADDR 0x74 //1110100

// For now, one object works...
ADXL345 adxl;
unsigned long lastStatus = millis();
double xyz[3];
 
void setup()
{
    Serial.begin(9600);

    Wire.begin();

    Serial.print("initing adxl0...");
    selectI2CChannels(0x1);
    adxl.powerOn();
    Serial.println("done");

    Serial.print("initing adxl1...");
    selectI2CChannels(0x2);
    adxl.powerOn();
    Serial.println("done");
}
 
void loop()
{
    unsigned long currentTime = millis();
    bool printStatus = false;

    if (currentTime > (lastStatus + 500))
    {
        printStatus = true;
        lastStatus = currentTime;
    }

    selectI2CChannels(0x1);
    adxl.getAccelemeter(xyz);
    if (printStatus)
        printXYZ("ONE");
 
    selectI2CChannels(0x2);
    adxl.getAccelemeter(xyz);
    if (printStatus)
        printXYZ("TWO");
}
 
void selectI2CChannels(int channels) 
{
    Wire.beginTransmission(TCA9548AADDR);
    Wire.write(channels);
    Wire.endTransmission();  
}

void printXYZ(char label[])
{
    Serial.print(label); Serial.print(": ");
    Serial.print(xyz[0]); Serial.print(",");
    Serial.print(xyz[1]); Serial.print(",");
    Serial.println(xyz[2]);
}

Credit for being able to figure out the code and switch between the two accelerometers should go to Kerry Wong as the basis for my test is from his blog.

I'm pretty excited about things at this point, they are really starting to come together. I think I'm past due for a cool video update showing a lot of what I've done come together. Back with that as soon as I can...