# WS2801LED Arduino Sketch¶

This sketch is used by Exercise: WS2801 RGB LED SPI Module.

## Full Source Code¶

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

  1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 // -*- 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. #include void setup() { SPI.begin(); // initialize SPI hardware } void loop() { static int cycle = 0; // on each iteration, shift out RGB data for several pixels, then delay to allow the device to update. for (int pixel = 0; pixel < 3; pixel++ ) { uint8_t red = 3 * (cycle + 32*pixel); uint8_t green = 5 * (cycle + 32*pixel); uint8_t blue = 7 * (cycle + 32*pixel); SPI.transfer( blue ); SPI.transfer( red ); SPI.transfer( green ); } delay(1); // delay 1 millisecond to allow outputs to update cycle++; // update the overall animation // add a delay to control the overall frame rate delay(20); }