I have been working non-stop for a week now trying to figure out how

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1

I have been working non-stop for a week now trying to figure out how to do the following with my xmas lights setup like the attached image shows.
I would like to fade from black to red on column1 row1, which is on Pin9, Pixel#49-40 then onto column2 row1, which is on Pin10, Pixel#0-9 fading from black to green, and then column3 row1, which is on Pin11, Pixel#0-9, fading from black to red and then have it move down to Column3, row2, which is on Pin11, Pixel#10-19 having it fade from black to green, and then move again to Column2, row2, Pin10, Pixel#10-19, and so on.
Sorry for the Newbie questions, as I have looked everywhere and tried to set pixels individually with no luck :-(.

I am using 3 - NeoPixel WS2812B strips that are 50 Pixels in length.

Thank you in advance,
Scott

07246245c005762fd3c9d392b38d609d.jpeg
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2

Here’s a rough draft of how you would address your pixels - assuming you could overlay an X/Y grid on top of your three columns (with y=0, x=0 being the upper left corner of your drawing and y=4, x=29 being the lower right):

#define NUM_LEDS_PER_STRIP 50
#define NUM_STRIPS 3
#define NUM_LEDS NUM_LEDS_PER_STRIP * NUM_STRIPS

#define COL_WIDTH 10
#define NUM_ROWS 5
CRGB leds[NUM_LEDS];

int XY(uint8_t x, uint8_t y) {
// determine what column we’re in
uint16_t base = 0;
if(x >= 10) base += NUM_LEDS_PER_STRIP;
if(x >= 20) base += NUM_LEDS_PER_STRIP;

// reduce x to the position in the specific column
x %= 10;

// columns B & C are wired the same
if(base > 0) {
if(y & 0x01) {
// odd rows, reverse the ordering
uint8_t rx = (COL_WIDTH - 1) - x;
base += ((yCOL_WIDTH) + rx);
} else {
base += ((yCOL_WIDTH) + x);
}
} else {
// column A is upside down, making this trickier
uint8_t ry = (NUM_ROWS-1) - y;
if(ry & 0x01) {
base += ((ryCOL_WIDTH)+x;
} else {
uint8_t rx = (COL_WIDTH-1) -x ;
base += ((ryCOL_WIDTH)+rx;
}
}

return base;
}

setup() {
FastLED.addLeds<WS2812B, 9>(leds, NUM_LEDS_PER_STRIP);
FastLED.addLeds<WS2812B, 10>(leds + NUM_LEDS_PER_STRIP, NUM_LEDS_PER_STRIP);
FastLED.addLeds<WS2812B, 11>(leds + (2*NUM_LEDS_PER_STRIP), NUM_LEDS_PER_STRIP);
}

void loop() {
for(int y = 0; y < NUM_ROWS; y++) {
for(int x = 0; x < COL_WIDTH*NUM_STRIPS; x++ ) {
leds[XY(x,y)] = CRGB::Red;
FastLED.show();
leds[XY(x,y)] = CRGB::Black;
}
}
}

From here then, you can just work in terms of X/Y’s like you were drawing on a grid.

3

Thank you sooooo much. It’s amazing that I have been working on this for a while and it takes you a couple of minutes to reply with a solution. I will let you know how it goes.
Thanks again Daniel

4

Thank you again for posting the code for the xmas lights, lol I’m still trying to figure out how to set every other 3 pixels green, but I forgot to also ask if there is a way to select multiple Pixels, for example, pix1,pix4,pix6,pix9 and then be able to utilize them later as a variable?

5

@Scott_S Hi Scott,
you could define them in an array. A quick example:

This one defines an array with 2 “groups” of 5 values each:

byte myGroups[2][5] = {
{ 12, 13, 14, 15, 16 }, // LEDs 12 to 16
{ 17, 21, 25, 39, 41 }
};

Later on you can assign colors to one of these “groups” by using a void like this:

void showGroup(byte groupID, byte color) {
for (i = 0; i < 5; i++) {
leds[myGroups[groupID][i].setHSV(color, 255, 150);
}
}

This would be used like this:

showGroup(0, 64);
FastLED.show();

This would set the leds 12 - 16 to yellow and turn them on.

Hope this helps,
Daniel

6

Yes, very much so. Thanks again. Once I get this thing 100%, I will post video and finished code.

7

So as promised, here is my long hand code, as I always seem to bypass simplistic coding… http://pastebin.com/3WSwq5Vp
I know, I am terrible at coding, but most of the time it works lol. Now, I just need to get some extra things done like fading and such.