OK, I need some help here. I have a ESP32 controller connected to a WS2812B 300 count LED strip and I can only get the first 75 LEDs to light up. When I set the LED Count to 76 or higher, then nothing lights up. I’m kind of new to the Arduino world so maybe I missed something. I have the Adafruit NeoPixel library added. I’m using an external 5V power supply with a 390-ohm resistor and a 1000 uf capacitor. Everything is wired just like this diagram; except I’m using pin 2. I had a more complicated script for what I was building, but I ended up just pulling some sample code off the Internet to see if I could get it working past 75. I’ve tried a different power supply, different resistor, different output pin, different brightness, different starting LED. Nothing helps. This is the code I currently have.
#include <Adafruit_NeoPixel.h>
#define LED_PIN 2 // Digital pin connected to the LED strip
#define LED_COUNT 75 // Number of LEDs in the strip
Adafruit_NeoPixel strip(LED_COUNT, LED_PIN, NEO_GRB + NEO_KHZ800);
void setup() {
strip.begin(); // Initialize the LED strip
strip.show(); // Turn off all LEDs initially
}
void loop() {
// Set all LEDs to red
strip.setBrightness(100); // a value from 0 to 255
for (int i = 0; i < LED_COUNT; i++) {
strip.setPixelColor(i, strip.Color(0, 255, 0)); // Green color (RGB values)
strip.show(); // Send the updated pixel colors to the strip
}
delay(1000); // Wait for 1 second before changing colors
strip.clear(); // set all LEDs to off
strip.show(); // push update to the WS2812B Led Strip
delay(1000);
}
It's a long shot, but check the value of strip.numPixels() to see if the malloc call in the constructor failed. I don't claim to have any familiarity with the library code, but it doesn't look like it's trying to allocate a large amount of memory for each LED.
What was the output with different starting led? For example 20 leds from 70 to 90?
If it shuts down at led n. 75 you probably have physical damage there.
So I thought it might be a physical problem as well, but I don't see any damage to the LED strip. Also, it seems like it should at least light up the first 75 LEDs and then not go any farther. I don't get any LEDs to light up.
van_der_decken might be on to something, even if I don't understand it. This morning I tried to hard code the number of LEDs by changing this code
//#define LED_COUNT 75 // Number of LEDs in the strip
Adafruit_NeoPixel strip(75, LED_PIN, NEO_GRB + NEO_KHZ800);
for (int i = 0; i < 75; i++) {
This works just fine if I keep the number at 75. But if I change the Adafruit_NeoPixel to 76, it doesn't work. I don't know how these libraries function, but something in this line of code seems to be the problem. I would be curious if anyone else out there can duplicate this issue.
So I'm looking online for solutions and I see another library called FastLED that gets used a lot. Does anyone know the difference between Adafruit_NeoPixel and FastLED. I might try switching it when I get some time, but it would be nice to understand it better.
The constructor calls updateLength() (in spite of the comment for updateLength()) which sets the pixel count to 0 if the malloc() fails.
/*!
@brief Change the length of a previously-declared Adafruit_NeoPixel
strip object. Old data is deallocated and new data is cleared.
Pin number and pixel format are unchanged.
@param n New length of strip, in pixels.
@note This function is deprecated, here only for old projects that
may still be calling it. New projects should instead use the
'new' keyword with the first constructor syntax (length, pin,
type).
*/
void Adafruit_NeoPixel::updateLength(uint16_t n) {
free(pixels); // Free existing data (if any)
// Allocate new data -- note: ALL PIXELS ARE CLEARED
numBytes = n * ((wOffset == rOffset) ? 3 : 4);
if ((pixels = (uint8_t *)malloc(numBytes))) {
memset(pixels, 0, numBytes);
numLEDs = n;
} else {
numLEDs = numBytes = 0;
}
}
Not sure why it fails. An esp32 should have plenty of ram.
Generally yes, however we should strive for teaching proper design in projects.
Something borderline might work today but not tomorrow.
Leaving potential problems in a design is never recommended.
Leaving poor coding in a noob’s software doesn’t teach them anything, same with electronic design.
That doesn't mean there is no problem. You didn't answer to my question about different start address.
If you believe the code is your problem, keep it at 75 and instead attach signal pin to second led signal pad. It should illuminate leds from 2 to 76.
to see how many pixels the object thinks it has. If the result is zero the storage allocation failed, a code problem. If not zero and it matches what you think you have it is probably a wiring error.
OK. This is the only ESP32 microcontroller I have and also the only LED strip. They aren't mine, so I'm reluctant to cut it up. I'm working on a project for someone else, but it's mostly just a proof of concept. I got the project to work, but for my own knowledge, I want to know why I can't go beyond 75 LEDs.
I set the LED_COUNT to 70 and tried moving the data connection to the next LED. That didn't work at all. No LEDs lit up. Weird. Am I doing it wrong? I'm assuming the data pin is directional since there is a little arrow on it showing which way to go. Any LEDs before the connection should just be ignored.
One other note. I noticed if I pinch the data wire between my fingers, I get a lot of flickering and random blinking on the strip just from the noise. But it does go past LED 75. This shows that I'm at least getting power to the rest of the strip. I even tried connecting the data wire after LED 75 and still nothing happens.
I'm going to keep messing with it. I really do appreciate all the feedback. You guys are great.
How does it tell me the answer to this? I don't have the serial display connected. I have one, but that is something new that I haven't messed with yet.
) has damaged either pixel 75 or 76. 