Light Paintbrush with Circuit Playground

Plug your Circuit Playground into your computer now using a USB cable, and launch the Arduino IDE. Double check that you've selected the board and port as in the Lesson #0 tutorial and are ready to upload code.

The code for the Light Paintbrush has two jobs:

• Read the on-board accelerometer to determine which color to set the NeoPixels
• Read the potentiometer connected to pin #10 to set the NeoPixel brightness

// ---------------------------------------------------------------------------
//Circuit Playground Light Paintbrush
// John Park
// for Adafruit Industries
//
// Use the Circuit Playground as a long exposure photography light paintbrush
// tilt to change color
// adjust brightness with the 10k potentiometer
//
 /*       X 
 *       __
 *      /  \  
 *  Y  |    |  -Y
 *      \__/
 *      
 *       -X
 */
//
// MIT license, check LICENSE for more information
//
//
// ---------------------------------------------------------------------------

#include <Adafruit_CircuitPlayground.h>
#include <Wire.h>
#include <SPI.h>

int sensorPin = A10;
int sensorValue = 0;
int brightVal = (20);

int X;
int Y;

int red = 0;
int green = 255;
int blue = 0;

void setup() {
  CircuitPlayground.begin();
  CircuitPlayground.clearPixels();
  CircuitPlayground.setBrightness(brightVal);  
}

void loop() {
  sensorValue = analogRead(sensorPin);
  brightVal = map(sensorValue, 0, 1023, 0, 225);

  X = CircuitPlayground.motionX();
  Y = CircuitPlayground.motionY();

  if ( (X>=1) && (Y<1) ) {      // x, -y = GREEN
    red = 0 ;
    green = 255;
    blue = 0;
  }
  else if ( (X <1 ) && (Y<1) ){ //-x, -y = BLUE
    red = 0;
    green = 0;
    blue = 255;
  }
  else if ( (X >=1) && (Y>=1) ){ // x,  y = RED
    red = 255;
    green = 0;
    blue = 0;
  }
  else if ( (X <1) && (Y>=1) ){  //-x,  y = YELLOW
    red = 255;
    green = 255;
    blue = 0;
  }

  for (int i=0; i<10;   i) {
    CircuitPlayground.setBrightness(brightVal);
    CircuitPlayground.strip.setPixelColor(i, red, green, blue);
  }   
  CircuitPlayground.strip.show();
}

Download the Code

You can press the button below to download the code. Unzip and move the directory CircuitPlaygroundLightPaintbrush to your Arduino sketch directory, then open it in the Arduino IDE and upload it to your Circuit Playground.

CircuitPlaygroundLightPaintbrush.zip

Next you'll assemble the Light Paintbrush.

Assemble the Light Paintbrush

With the software loaded onto the Circuit Playground, your Light Paintbrush will need power and one additional sensor -- a potentiometer -- to control brightness. You'll use the battery holder as both power supply and handle for your Light Paintbrush. This is expedient, inexpensive, and a great example of form following function. You could build a nice enclosure for the project if you like, but the Light Paintbrush works well without one.

The first build step is to attach leads to the potentiometer. The potentiometer uses three connections to the Circuit Playground -- ground, signal, and voltage. The ground and voltage are references for the varying resistance of the middle signal leg as the knob is turned. The Circuit Playground reads these changes as analog values from 0 to 1023, which are then remapped to NeoPixel brightness values in the software.

Cut one clip end off of each alligator clip lead, and strip away a bit of insulation to expose the wire. Tin the potentiometer legs with solder, tin the wires, and then solder the wires to the legs in the order shown here.

Then, clip the leads to the pads on the Circuit Playground:

• black to GND
• yellow to #10 
• red to 3.3V

Next, use a small piece of foam double-stick tape to connect the battery case to the back of the Circuit Playground.

Finally, use some foam tape to attach the potentiometer to the battery case.

 

That's it, your Light Paintbrush is complete!

Turn it on and try tilting the brush to change colors, and adjust brightness with the knob.

Now comes the artistic part -- time to make some light paintings!

Paint with Light

Now that you've built it , in order to paint with your Light Paintbrush you'll need a dark place and a camera or smartphone with "bulb" or long exposure mode.

On a camera, look for a "B" on the dial or check the far end of the shutter values. Bulb may require a held shutter, so it can be convenient to use a shutter in the 10-to-30 second range (notated as 10", 20", 30" and so on), or a remote trigger.

For smartphones there are many apps available -- just search for "long exposure" or "light trails" in the app store of your choice.

Now, head to a darkened room or outdoors at night. Set your camera or smartphone on a table or tripod, put it in long exposure mode with a small aperture to keep the scene fairly dark, and press the shutter.

Turn on your Circuit Playground Light Paintbrush, set the brightness knob to a medium setting, and move the Light Paintbrush in some circles and arcs. When you're done, press the camera shutter again and check your photo.

It may take some tuning to get the brightness and focus just right -- it's very helpful to have an assistant -- but once you do you'll see beautiful streaks of light with colors changing depending on the rotation arc of your arm or how you twist your wrist.

This image was a single streak during a five second exposure.

For these jellyfish-like images, the brightness knob was twisted on and off while moving and twisting the brush.

Less can be more.

More can also be more.

Here I illuminated my face briefly as well by pointing the Light Paintbrush at myself.

An external flash (or bright light turned on and off briefly) can help add your subject to the photograph without blurring.

Enjoy creating art with your Circuit Playground Light Paintbrush!