Christmas Shield
From Alpha One Labs
This was inspired by Alpay's Christmas tree project. The idea is to allow a single Arduino to control any number of lights (or relays or motors with appropriate diodes).
I'll write a Library for the shield that's relatively simple to use, and may even be able to add PWM.
[edit] Operation
Four 74595 shift registers are chained together to form a 32-bit shift register. The AVR's hardware SPI will be used to upload the display data, with the SS line used to clock the output latch. The SS line will be controlled manually rather than by hardware, since otherwise it would be flipped for every byte, and there would be flickering.
The shift register outputs are connected through 4-amp 60-volt transistors to the outputs.
For more theory about the circuit see [1]
For a discussion of SPI see [2]
[edit] Schematic
[edit] Eagle Files
- Media:Christmas_Shild.sch.ps Remove the .ps extension to open in Eagle
- Media:Christmas_Shield.brd.ps Remove the .ps extension to open in Eagle
