ESP32 Flashing

I have successfully flash 0.8.6 and 0.9.0-b1 to two different ESP32 with NodeMCU PyFlasher as well with “ESP32 DOWNLOAD TOOL V3.6.8” and in all instances I just cannot detect WLED wifi with my or my wife’s cel phone.

I suspect that after flashing the firmware I am not booting the ESP32 correctly.

What am I doing wrong?


I assumed I was doing something wrong because a video on you tube, the author says he flashed the ESP32 with

Flashing with Arduino IDE did the trick, just needed to install some needed libraries (AsyncTCP and FastLed)

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Hi @matematiko, another good way is to use VSCode as Text-Editor and install the extension “PlatformIO” - with this all you need to do is "open the WLED folder (where you cloned the repro) and select “build”.

The good thing ujsing PlatformIO is, that you do not need to care about getting the correct libraries (like you need when using Arduino IDE) and the every project has it’s own set of libraries and does not effect others.

Hello @Def3nder, I will download and try VS Code this evening because I definitely want to tinker with WLED code.
I assume (and hope) that you are familiar with WLED code and I have another question, I want to connect 2,100 pixels to the same ESP32 controller. The pixels do not need to blink 20 times per second,each pixel needs to receive its corresponding data only once, do you know what part of the code I need to modify to accomplish this? I am not asking for the whole solution, just to be send in the right direction.

Thanks for your help.

P.S. Just in case you are curious: What I have is all these 2,100 pixels installed in the roof’s eave all around the house functioning as accent lights. I already accomplish this by setting WLED to control 550 pixels, the output of the controller (which is installed in a linen closet in the middle of the house) is connect to four inputs of a logic/voltage shifter and each out goes to one of the 550 pixels string. This system is already working fine and I control it with Alexa via Home Assistant. In the future I want to do something similar around the fence and in this case I wont be able to do it the same way.

Hi @matematiko, I don’t think that 2.100 pixel in a row will work.

The maximum of 1.500 pixel is defined in WLED00.ino line 408++:
#define MAX_LEDS 1500
#define MAX_LEDS_DMA 500

I think you could get problems with the ESP rebooting or getting unstable, as the processing would take reasonable longer.

But: give it a try :smile:

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I think I read that about 700 was actually the max.

I was able to do 1,500 without problems (With ESP32, not sure if ESP8266 can handle that many)

Despite the fact that I changed the code (as suggested by Def3nder) to accept a max of 2100, WLED still says that 1,500 is the maximum. Weird!

You will also need to change it in the LED settings HTML in line 85 of html_settings.h :innocent:
It is true that, as opposed to the ESP8266, the ESP32 will not run out of memory at 2K LEDs.
However, I still cannot recommend it because the LEDs will run at a visibly choppy refresh rate of less than 15 fps.


Aircookie, it worked. I am running now 2,069 pixels with no issues. The slow refresh rate (whatever it is) is not noticeable perhaps because the pixels are displaying a solid color.

Not sure if I should be concerned about the controller getting hot.

Like I mentioned above, for this particular setup I want the controller to send the data only once (and again only if color is changed) and if this is very difficult then refresh once every second or every minute. I am thinking that I need to look in the FastLED library for this… any ideas? Thanks.


No, don’t worry. Glad it is working! The refresh rate is a non-issue on a solid color, you will only notice it when running fast effects. ESP32 Overheating is no concern either, it does not have to compute significantly more just because of a few extra leds :slight_smile: Refresh rate in Solid mode is 2 fps (to combat flicker on installations without a levelshifter) and 42 fps for most other effects.


Thanks @Aircoookie for amazing project WLED. it is coool.
hi @matematiko, i just have try to increase my led to 1800 led and this link video

and i want to try to 2100 led.

@Aircoookie , excellent explanation, thanks for taking the time.

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@ yusufsulaiman Nice… keep it up.

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Ive just flashed with NodeMCU-PyFlasher-4.0-x64 and it worked.

But I seem to be stuck in boot mode after restarting the device, I can just keep flashing it.

How do I exit boot mode?


Hi @1liminal1 ,

did you manage to flash a simple sketch to the ESP32 ? (without boot loops)

Try to do this first (either with Arduino IDE or with Plattform IO).

Is there anything else than the LED strip attached to any PIN ?
Do you have anything hooked up to pins 6…11 or 12?

If yes, pls. try to boot without anything attached to the ESP32.

…from 0.12 on the PINs can easily be selected in the UI later - no need to choose the right PIN first.

Good luck !

Thanks for that, appreciate it :slight_smile:

I did fix it, I just cant remember how now lol

Anyway, alls well that ends well