Electronics

Tasks

• Test current draw on one Beam and on Ray
• Identify and replace incorrect value resistors on Beams
• Mount beams on board so that coverings can be tested
• Get buildroot installed on Mac
• Test compile code for gumstix
• Determine if new gumstix is needed
• Complete alternative Ray design
• Build ray prototype
• Order replacement green LEDs for incorrect ones from Mouser.com (wide angle green)

Design

Beams

Beam PCB

The Solarium will be lit by LEDs. Multiple clusters of 3 LEDs (red, green and blue) will be used to create the color "pixels" that will paint the dome. "Pixel" isn't exactly right since the LEDs will not be in an orderly, square grid. They will be spaced regularly every 4" or 5" (a design point that needs to be solidified) however, because the are on a curved surface, they will not necessarily align. Furthermore their light will not be distinct squares. Instead it will be overlapping round pools.

To avoid confusion these 3 LED clusters will be called Beams. These LEDs will be soldered to a small PCB that will help hold the LEDs together and provide some structure to secure the beams to the dome.

A 4 conductor ribbon cable will connect each beam to its controller (see Rays).

Rays

Ray PCB

Each beam must be controlled by something that will manage its color and brightness. This is done by the Ray. Each ray will control 16 beams. Each ray will use three NXP PCA9635 devices to control the rays. This devices communicates via the I2C serial interface with the Solarium controller.

Controller

Each of the approximately 33 rays will connect to the Solarium controller. This is a Gumstix Verdex running custom code written for the Solarium.

Start/Stop

There needs to be a way to start and stop the Solarium show. There are a few ways to do this, each with trade offs.

1. On/off switch on Solarium

• • Pros: Turns on exactly when needed, off exactly when needed
  • Cons: Requires human interaction twice a day

1. Light sensor (average ambient light over 5 minutes)

• • Pros: Turns on/off automatically when light conditions are right
  • Cons: Could be confused by parked art car/maybe moon.

1. Solar cell voltage sensor

• • Turns on automatically when voltage drops (e.g., no more sun) and off when voltage increases
  • Could be fooled by clouds, low light days. Could turn on at sun set rather than when truly dark.

1. 24 hour timer

• • Pros: Automatic, immune to ambient light conditions
  • Cons: ??

Additionally, each of these methods could be controlled by the gumstix or by independent circuitry that controls the on/off line of the DC/DC converters.