Hi all, Completely new user to Arduino and fastled.I have a strip of ws2812b

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1

Hi all,
Completely new user to Arduino and fastled.I have a strip of ws2812b led’s but I am having great difficulty in reversing the direction of the led’s.I can make 5 leds travel the length of the strip (150 leds) but how do you get them to run the other way i.e 150 to 0.Any help would be greatly appreciated.Thank you.

2

Replace i by (NUM_LEDs -i-1)

for(i=0; i<NUM_LEDs; i++)
{ int position= NUM_LEDs-i-1c; strip.setPixelColor(position, strip.Color(i,position,0));}

3

Hi Walter.Thank you for your very swift reply.I will try that.

4

Sorry the c after the 1 is a typo.

5

Thank you.Noted.

6

Hi again.I have looked at my code and it is quite different to http://yours.So I am not sure how to integrate http://it.My code is as follows.
#include <FastLED.h>
#define LED_DT 6
#define COLOR_ORDER GRB
#define LED_TYPE WS2812
#define NUM_LEDS 300
uint8_t max_bright = 255;
struct CRGB leds[NUM_LEDS];

int index1;
int index2;
int index3;
unsigned long initialtime;

void setup() {
delay (1000);
LEDS.addLeds<LED_TYPE, LED_DT, COLOR_ORDER>(leds, NUM_LEDS);
FastLED.setBrightness(max_bright);
index1 = 0;
// index2 = 0;
// index3 = 0;
initialtime = millis();

void FASTLED() {
for(int a =0;a<=299; a++){
FastLED.clear();
set5leds(index1);
index1 = (index1 + 1) % (NUM_LEDS - 5);
if (millis() - initialtime > 1000) {

}
set5leds(index2);
index2 = (index2 + 1) % (NUM_LEDS - 5);
if (millis() - initialtime > 2700) {

set5leds(index3);
index3 = (index3 + 1) % (NUM_LEDS - 5);
if (millis() - initialtime > 3000) {
}
FastLED.show();
delay (1);
}
}
return 0;
}

void set5leds(int pos) {
leds[pos].setRGB (255, 255, 0);
leds[pos + 1].setRGB (255, 255, 0);
leds[pos + 2].setRGB (255, 255, 0);
leds[pos + 3].setRGB (255, 255, 0);
leds[pos + 4].setRGB (255, 255, 0);
return 0;
}

7

Whenever you call set5leds replace pos by (NUM_LEDS-pos-1).

In the routine itself replace all the positions in the square bracket index to Leds by
leds[constrain(pos,0, NUM_LEDS-1)]so as not to get out of range and mess up the fastlib.
You are on a perfect way, neat clearly structured program, a pleasure to read.
Alternatively you can add another parameter to set5leds e.g. set5leds(int index, bool reverse]
and at the begining add the statement
if(reverse) pos=NUM_LEDS-pos-1

This will NOT have any effect on where you call the function. A parameter is just a local variable writing to it will not effect the caller.

8

Hi Walter.Thank you so much for your help and thank you for the compliment too.I will try this now and let you know the result.