LPD6803.cpp

/*!
 * @file LPD6803.cpp
 *
 * @mainpage LPD6803 RGB Pixels
 *
 * @section intro_sec Introduction
 *
 * Example to control LPD6803-based RGB LED Modules in a strand
 * Original code by Bliptronics.com Ben Moyes 2009
 * Use this as you wish, but please give credit, or at least buy some of my
 *LEDs!
 *
 * Code cleaned up and Object-ified by ladyada, should be a bit easier to use
 *
 * Library Optimized for fast refresh rates 2011 by michu@neophob.com
 */

#include "LPD6803.h"
#include <TimerOne.h>

// the arrays of ints that hold each LED's 15 bit color values
static uint16_t *pixels;
static uint16_t numLEDs;

static uint8_t dataPin, clockPin;

/*!
 * @brief Various modes for the LPD6803
 */
enum lpd6803mode { START, HEADER, DATA, DONE };

static lpd6803mode
    SendMode;         // Used in interrupt 0=start,1=header,2=data,3=data done
static byte BitCount; // Used in interrupt
static uint16_t LedIndex; // Used in interrupt - Which LED we are sending.
static byte BlankCounter; // Used in interrupt.

static byte lastdata = 0;
static uint16_t swapAsap =
    0; // flag to indicate that the colors need an update asap

// Interrupt routine.
// Frequency was set in setup(). Called once for every bit of data sent
// In your code, set global Sendmode to 0 to re-send the data to the pixels
// Otherwise it will just send clocks.
/*!
 * @brief Function for writing to the LEDs
 */
void LedOut() {
  // PORTB |= _BV(5);    // port 13 LED for timing debug

  switch (SendMode) {
  case DONE: // Done..just send clocks with zero data
    if (swapAsap > 0) {
      if (!BlankCounter) // AS SOON AS CURRENT pwm IS DONE. BlankCounter
      {
        BitCount = 0;
        LedIndex = swapAsap; // set current led
        SendMode = HEADER;
        swapAsap = 0;
      }
    }
    break;

  case DATA: // Sending Data
    if ((1 << (15 - BitCount)) & pixels[LedIndex]) {
      if (!lastdata) { // digitalwrites take a long time, avoid if possible
        // If not the first bit then output the next bits
        // (Starting with MSB bit 15 down.)
        digitalWrite(dataPin, 1);
        lastdata = 1;
      }
    } else {
      if (lastdata) { // digitalwrites take a long time, avoid if possible
        digitalWrite(dataPin, 0);
        lastdata = 0;
      }
    }
    BitCount++;

    if (BitCount == 16) // Last bit?
    {
      LedIndex++;             // Move to next LED
      if (LedIndex < numLEDs) // Still more leds to go or are we done?
      {
        BitCount = 0; // Start from the fist bit of the next LED
      } else {
        // no longer sending data, set the data pin low
        digitalWrite(dataPin, 0);
        lastdata = 0;    // this is a lite optimization
        SendMode = DONE; // No more LEDs to go, we are done!
      }
    }
    break;
  case HEADER: // Header
    if (BitCount < 32) {
      digitalWrite(dataPin, 0);
      lastdata = 0;
      BitCount++;
      if (BitCount == 32) {
        SendMode =
            DATA; // If this was the last bit of header then move on to data.
        LedIndex = 0;
        BitCount = 0;
      }
    }
    break;
  case START:          // Start
    if (!BlankCounter) // AS SOON AS CURRENT pwm IS DONE. BlankCounter
    {
      BitCount = 0;
      LedIndex = 0;
      SendMode = HEADER;
    }
    break;
  }

  // Clock out data (or clock LEDs)
  digitalWrite(clockPin, HIGH);
  digitalWrite(clockPin, LOW);

  // Keep track of where the LEDs are at in their pwm cycle.
  BlankCounter++;

  // PORTB &= ~_BV(5);   // pin 13 digital output debug
}

//---
LPD6803::LPD6803(uint16_t n, uint8_t dpin, uint8_t cpin) {
  dataPin = dpin;
  clockPin = cpin;
  numLEDs = n;

  pixels = (uint16_t *)malloc(numLEDs);
  for (uint16_t i = 0; i < numLEDs; i++) {
    setPixelColor(i, 0, 0, 0);
  }

  SendMode = START;
  BitCount = LedIndex = BlankCounter = 0;
  cpumax = 50;
}

//---
void LPD6803::begin(void) {
  pinMode(dataPin, OUTPUT);
  pinMode(clockPin, OUTPUT);

  setCPUmax(cpumax);

  Timer1.attachInterrupt(
      LedOut); // attaches callback() as a timer overflow interrupt
}

//---
uint16_t LPD6803::numPixels(void) { return numLEDs; }

//---
void LPD6803::setCPUmax(uint8_t m) {
  cpumax = m;

  // each clock out takes 20 microseconds max
  long time = 100;
  time *= 20; // 20 microseconds per
  time /= m;  // how long between timers
  Timer1.initialize(time);
}

//---
void LPD6803::show(void) { SendMode = START; }

//---
void LPD6803::doSwapBuffersAsap(uint16_t idx) { swapAsap = idx; }

//---
void LPD6803::setPixelColor(uint16_t n, uint8_t r, uint8_t g, uint8_t b) {
  uint16_t data;

  if (n > numLEDs)
    return;

  data = g & 0x1F;
  data <<= 5;
  data |= b & 0x1F;
  data <<= 5;
  data |= r & 0x1F;
  data |= 0x8000;

  pixels[n] = data;
}

//---
void LPD6803::setPixelColor(uint16_t n, uint16_t c) {
  if (n > numLEDs)
    return;

  pixels[n] = 0x8000 | c;
}