Beacon3

Beacon3 will be a beacon for the top of our flag(less?) pole for Burning Man 2011. It will be simpler than Beacon2 as time is limited to get it done, but we want a brighter beacon.

Ideas

• Beacon Unit
  • Same enclosure as Beacon2 can be used to save time, just remove PCBs and replace with these
  • Planar PCB that fits onto the spindle, which the other boards plug into vertically
    • Single MCU this time, as there are fewer LEDs
    • Same light sensor and (lack of) charging circuitry as Beacon2 can also be used
    • Regulator on planar will only be needed for wireless functionality, MCU can operate over whole battery range as can LED drivers
      • Figure out how to level shift for the XBee (MCU running at battery voltage, XBee needs 3.3V)
    • Will use an ATmega328p for the MCU, makes it Arduino-compatible
  • 4 RGBW LED units on Star boards and heat sinks at 12, 3, 6, and 9
    • Current thought is Cree MC-E ~2.5W per component colour RGBW LEDs
  • 4 RGBW LED driver boards (custom) at 1:30, 4:30, 7:30, and 10:30
    • 4x NXP SSL3250A chips on each board looks good to drive the RGBW LEDs
      • Will drive them at 200mA per component colour constantly, and 500mA flashes of 820mS
      • This chip has a fixed I2C address though so an I2C mux would be needed on each LED board
        • The PCA9545 looks perfect for this, I2C controlled 4:1 I2C mux and can be "turned off" so that there's no need for a planar mux
• Remote Control Unit
  • Having a remote that would make the beacon extra-noticeable when a button was pressed would be cool
  • To get long enough range to be useful, we'd want ~50mW
  • XBee is probably the best way to go, but need to look at power draw for the RX side and would have to custom-design a remote control unit
  • Remote Control Unit could just be:
    • Arduino Fio
    • XBee Series 1 RP-SMA (plugs directly into Arduino Fio)
    • Rubber-duck antenna
    • LiIon pack (plugs directly into Arduino Fio)

Project Status

• 2011-07-19: Initial design started.
• 2011-07-23: Schematic for LED driver board started and almost completed.