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[on:]

Hi, im trying to use the MAP function to gradually fade in-between colors. When I use this code it does the first fade, but then JUMPS back and does it over, without executing the second fade.

Any advice very appreciated, THANKS




#include "LPD8806.h"
#include "SPI.h"

// Example to control LPD8806-based RGB LED Modules in a strip

/*****************************************************************************/

// Number of RGB LEDs in strand:


int nLEDs = 4;

// Chose 2 pins for output; can be any valid output pins:
int dataPin  = 11;
int clockPin = 13;

// Magenta:
#define COLOR1_R 0
#define COLOR1_G 0
#define COLOR1_B 255
// Blue:
#define COLOR2_R 255
#define COLOR2_G 0
#define COLOR2_B 0

// First parameter is the number of LEDs in the strand.  The LED strips
// are 32 LEDs per meter but you can extend or cut the strip.  Next two
// parameters are SPI data and clock pins:
LPD8806 strip = LPD8806(4, dataPin, clockPin);

// You can optionally use hardware SPI for faster writes, just leave out
// the data and clock pin parameters.  But this does limit use to very
// specific pins on the Arduino.  For "classic" Arduinos (Uno, Duemilanove,
// etc.), data = pin 11, clock = pin 13.  For Arduino Mega, data = pin 51,
// clock = pin 52.  For 32u4 Breakout Board+ and Teensy, data = pin B2,
// clock = pin B1.  For Leonardo, this can ONLY be done on the ICSP pins.
//LPD8806 strip = LPD8806(nLEDs);

void setup() {
  // Start up the LED strip
  strip.begin();

  // Update the strip, to start they are all 'off'
  strip.show();
}

void loop() {
  int r,g,b;
  uint16_t i, j, k;
 
  for (j=0; j < 140; j++) {
    r = map(j, 0, 140, COLOR1_R, COLOR2_R);
    g = map(j, 0, 140, COLOR1_G, COLOR2_G);
    b = map(j, 0, 140, COLOR1_B, COLOR2_B);
   
    for (i=0; i < 4; i++) { 
      strip.setPixelColor(i,(strip.Color(r,g,b) ));
    } 
   
    strip.show();   // write all the pixels out
    delay(50);
  }

  for (k=0; k < 140; j++) {
    r = map(k, 0, 140, COLOR2_R, COLOR1_R);
    g = map(k, 0, 140, COLOR2_G, COLOR1_G);
    b = map(k, 0, 140, COLOR2_B, COLOR1_B);
   
    for (i=0; i < 4; i++) { 
      strip.setPixelColor(i,(strip.Color(r,g,b) ));
    } 
   
   strip.show();   // write all the pixels out
    delay(100);
  }
}

[Reply #1 on:]

Code:

  for (k=0; k < 140; j++) {

This will never increment 'k' so the loop will never end.  It will repeat with k=0 forever.

[Reply #2 on:]

thanks!

is it the extra space in the code, k not being defined properly?

The code for j does seem to give me a gradual fade. Why not k?

really appreciate the guidance

[Reply #3 on:]

sorry, misplaced a j and k. still it skips when I run it

[Reply #4 on:]

sorry, misplaced a j and k. still it skips when I run it

If you fixed that problem (changed "j++" to "k++") I see no reason why it wouldn't work.  Perhaps you should show your current code.

[Reply #5 on:]

Thanks for the patience and insight John.

When I run the current code here is what happens:

Red fade to Blue  -abrupt jump to red fade to blue fade to red -abrupt jump to blue fade to red fade to blue -abupt jump to red fade to blue fade to red -abrupt jump to blue, it just keeps repeating.

I want a smooth fade, back and forth, like a sine wave. Thanks for any insight.

Here is my code:

#include "LPD8806.h"
#include "SPI.h"

// Example to control LPD8806-based RGB LED Modules in a strip

/*****************************************************************************/

// Number of RGB LEDs in strand:


int nLEDs = 4;

// Chose 2 pins for output; can be any valid output pins:
int dataPin  = 11;
int clockPin = 13;

// Red:
#define COLOR1_R 255
#define COLOR1_G 0
#define COLOR1_B 0
// Blue:
#define COLOR2_R 0
#define COLOR2_G 0
#define COLOR2_B 255

LPD8806 strip = LPD8806(4, dataPin, clockPin);

void setup() {
  // Start up the LED strip
  strip.begin();

  // Update the strip, to start they are all 'off'
  strip.show();
}

void loop() {
  int r,g,b;
  uint16_t i, j, k;
 
  for (j=0; j < 100; j++) {
    r = map(j, 0, 100, COLOR1_R, COLOR2_R);
    g = map(j, 0, 100, COLOR1_G, COLOR2_G);
    b = map(j, 0, 100, COLOR1_B, COLOR2_B);
   
    for (i=0; i < 4; i++) { 
      strip.setPixelColor(i,(strip.Color(r,g,b) ));
    } 
   
    strip.show();   // write all the pixels out
    delay(120);
  }

  for (k=0; k < 100; k++) {
    r = map(k, 0, 100, COLOR2_R, COLOR1_R);
    g = map(k, 0, 100, COLOR2_G, COLOR1_G);
    b = map(k, 0, 100, COLOR2_B, COLOR1_B);
   
    for (i=0; i < 4; i++) { 
      strip.setPixelColor(i,(strip.Color(r,g,b) ));
    } 
   strip.show();
    delay(120);
  }
}

[Reply #6 on:]

Your code looks fine so I can only assume that the fault is in the library.

[Reply #7 on:]

How might one discern this? reload the library? What other code options do I have for achieving this fade effect?

[Reply #8 on:]

Color cycling is easier in another color space, see - http://arduino.cc/forum/index.php/topic,95019.msg719982.html#msg719982 - for code

[Reply #9 on:]

hey Robtillart,

Seems that code is for a RGB LED, but Im using the LPD8806 strips.

Any ideas?

[Reply #10 on:]

use

Code:

strip.setPixelColor(i,(strip.Color(r,g,b) ));

where in the other code sets a single RGB led.