Arduino Sketch WS2801LED

Full Source Code

The full code is all in one file WS2801LED.ino.

// -*- mode:c++; -*-
/// @file WS2801LED.ino
/// 
/// @brief Example for driving several WS2801 RGB LED modules over SPI on an Arduino UNO.
///
/// @author Garth Zeglin
/// @date 2014-09-13
///
/// @remarks The WS2801 LED driver has three current controlled LED outputs with
/// 8-bit precision (256 levels).  It is controlled over SPI by sending 24 bits
/// of pixel data at up to 25MHz rate.  Additional data is then relayed to the output
/// SPI pins to feed daisy-chained drivers.  Once the bus is quiescent for 500
/// microseconds, the data is applied to the outputs and the chip is ready to
/// receive more values.
///
/// So a large number of of drivers can be fed on each channel, limited only by
/// the overall refresh rate.  But the data must be fed without interruption to
/// avoid prematurely ending the cycle.
///
/// The actual color data sequence depends upon the wiring of the module; on one
/// particular strip light tested the actual sequence was blue-red-green.
///
/// Note that the relay scheme means that first three bytes output feed the
/// first module, the second three the second module, etc.  In other words, the
/// strand is not a shift register.  Extra data has no effect.

/// This sketch assumes the following electrical connections from the Arduino to
/// the first module in a chain:

/// PIN11 (MOSI)  ->  DAT
/// PIN13 (SCK)   ->  CLK
/// GND           ->  GND

// Include the SPI library.

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