Hi guys, newbie here and i need some help.

Jaja1 · June 20, 2018, 5:14pm

Hi guys, newbie here and i need some help. I just bought this item (WS2812 8x8 rgb led matrix) from aliexpress and I can’t seem to make it work properly.

I tried the tutorial from fastled website but I can only make the first led blink.
im trying to power it using an 1850 battery and an LM2596 buck converter at 5v.

am i missing something? do i need to put some extra codes or something or is the current flow too low? the LM2596 is supposed to give out 3A.

any help would be appreciated!
https://www.aliexpress.com/item/WS2812-LED-5050-RGB-8x8-64-LED-Matrix-for-Arduino/32600043941.html

Yves_BAZIN · June 20, 2018, 5:26pm

Could you share the code on gist ?

Jeremy_Spencer · June 20, 2018, 5:42pm

Which controller are you using?

Jaja1 · June 20, 2018, 5:55pm

im using an arduino uno.

heres my current code, also I put red but it blinks green. im lost.

[#include <FastLED.h>
#define NUM_LEDS 64
#define DATA_PIN 6

CRGB leds[NUM_LEDS];
int i = 0;

void setup() {
FastLED.addLeds<WS2812, DATA_PIN>(leds, NUM_LEDS);
}

void loop() {
leds[i] = CRGB::Red;
FastLED.show();
delay(500);

leds[i] = CRGB::Black;
FastLED.show();
delay(500);
i++;

if(i==63) i=0;
}]

Yves_BAZIN · June 20, 2018, 6:04pm

@Jaja1 try this
Add #define FASTLED_ALLOW_INTERRUPTS 0
Before the #include ‘fastled.h’
Also in the addleds<ws2812,data_pin,GRB>(leds,NUM_LEDS);

Jaja1 · June 20, 2018, 6:09pm

still doesn’t work bro, the 2nd led only blinks red once then nothing

Yves_BAZIN · June 20, 2018, 6:13pm

@Jaja1 is the ground of the arduino plugged with the ground of your power supply ? If yes
Try this in your code reduce the NUM_LEDS to 5 and power the leds using the arduino pins.
The 2812 should work even with a lower voltage
Stupid question are you connecting to the GPIO 6 and not the 6th PIN ?

Jaja1 · June 20, 2018, 6:17pm

yes, after the LM2596 converts the voltage to 5v, i connect its ground to both the arduino and the led matrix.

JP_Roy · June 20, 2018, 6:25pm

There is no real ‘loop’ to sequence through your leds in your code.

You need a line like…

for (int i = 0; i < NUM_LEDS; i++) {

  // here you do your stuff

}

JP_Roy · June 20, 2018, 6:31pm

Just noticed the i++; statement but still… I think that loop() re-initialises the variables each time it gets executed and therefore always sets i = 0 !!

Andrew_Tuline · June 20, 2018, 6:43pm

Jaja, if you want to light up multiple LED’s, then your code is incorrect as you have no loop.

Please start out with the various examples included with FastLED instead of what you have provided.

Please also include links when referring to any online tutorials you have tried.

Jaja1 · June 20, 2018, 7:04pm

this is the tutorial i have followed, the fastled website brought me here.

can you suggest a better tutorial?

Andrew_Tuline · June 20, 2018, 7:09pm

Try the examples included with FastLED at:

Just change the definitions to match your pins and LED’s.

marmil · June 20, 2018, 7:23pm

@Jaja1 Did you try any of the FastLED examples?

Try out the FirstLight one.

Even though Jaja’s code above isn’t exactly what we’re use to seeing, it SHOULD work. (The code worked for me when I tested it.)

Also, Jaja, when sharing code please put it on http://gist.github.com and share the link. This way it will always be formatted correctly on all devices and line numbers can be referenced for discussion.

Jeremy_Spencer · June 20, 2018, 7:24pm

Use this sketch to work out the correct colour order for your leds…

github.com

FastLED/FastLED/blob/master/examples/RGBCalibrate/RGBCalibrate.ino

#include "FastLED.h"


////////////////////////////////////////////////////////////////////////////////////////////////////
//
// RGB Calibration code
//
// Use this sketch to determine what the RGB ordering for your chipset should be.  Steps for setting up to use:

// * Uncomment the line in setup that corresponds to the LED chipset that you are using.  (Note that they
//   all explicitly specify the RGB order as RGB)
// * Define DATA_PIN to the pin that data is connected to.
// * (Optional) if using software SPI for chipsets that are SPI based, define CLOCK_PIN to the clock pin
// * Compile/upload/run the sketch

// You should see six leds on.  If the RGB ordering is correct, you should see 1 red led, 2 green
// leds, and 3 blue leds.  If you see different colors, the count of each color tells you what the
// position for that color in the rgb orering should be.  So, for example, if you see 1 Blue, and 2
// Red, and 3 Green leds then the rgb ordering should be BRG (Blue, Red, Green).

This file has been truncated. show original

marmil · June 20, 2018, 7:24pm

@JP_Roy i is a global variable so it does not get reset each time through the main loop.

Jeremy_Spencer · June 20, 2018, 7:31pm

Some of the matrix boards have a mistake on the silkscreen, Data In and Data out are reversed. Try connecting your controller to the data out pin.

Ken_White · June 20, 2018, 8:23pm

@Jaja1 - Here is my test new products sketch located at:

I use it to test any new RGB Led products that I purchase. All you have to do is change line 9 to 64, upload it to your Uno and run it.

Yves_BAZIN · June 20, 2018, 8:48pm

@JP_Roy actually no i keeps on getting increase. The loop doesn’t reset the variables. @Jaja1 code is correct.

JP_Roy · June 20, 2018, 8:57pm

@Yves_BAZIN I have to admit I did not even try the code and only offered a wild guess. I just remembered something about static variables and incorrectly applied the meaning in this context.