Blocked ESP32

Popcornettay

Blocked ESP32

Postby Popcornettay » Mon Nov 03, 2025 4:12 pm

Hello,

So I'm a beginner with ESP and I wanted to flash a firmware on my ESP32-S3-DevKitC-1U. Unfortunatly, since then I cannot flash any other firmwares. The board is still correctly detected on the PC and the chip is still responding (tested it with the esptool flash_id command in ESP_IDF). And btw, the LED on pin 38 is not turning on anymore and the other red is always on wathever I do. Could someone please help me recover my device ?

Thank you already for reading the post 8-)

Minatel
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Re: Blocked ESP32

Postby Minatel » Tue Nov 04, 2025 1:38 am

Hi,

The red LED is the power LED, so you can't control it via the ESP32-S3. The RGB LED is an addressable LED named SK6812MINI (like WS2812), so you can't control this LED by just toggling the GPIO.

Have you tried the blink example?

ESP32_kid
Posts: 16
Joined: Tue Oct 28, 2025 10:02 pm

Re: Blocked ESP32

Postby ESP32_kid » Tue Nov 04, 2025 4:18 am

That board should have just one neopixel on IO38

The available macro should work. There's a few ways to control rgb pixel.
Here's one:

Code: Select all

/*
  BlinkRGB

  Demonstrates usage of onboard RGB LED on some ESP dev boards.

  Calling digitalWrite(RGB_BUILTIN, HIGH) will use hidden RGB driver.

  RGBLedWrite demonstrates control of each channel:
  void rgbLedWrite(uint8_t pin, uint8_t red_val, uint8_t green_val, uint8_t blue_val)

  WARNING: After using digitalWrite to drive RGB LED it will be impossible to drive the same pin
    with normal HIGH/LOW level
*/
//#define RGB_BRIGHTNESS 64 // Change white brightness (max 255)

// the setup function runs once when you press reset or power the board

void setup() {
  // No need to initialize the RGB LED
}

// the loop function runs over and over again forever
void loop() {
#ifdef RGB_BUILTIN
  digitalWrite(RGB_BUILTIN, HIGH);  // Turn the RGB LED white
  delay(1000);
  digitalWrite(RGB_BUILTIN, LOW);  // Turn the RGB LED off
  delay(1000);

  rgbLedWrite(RGB_BUILTIN, RGB_BRIGHTNESS, 0, 0);  // Red
  delay(1000);
  rgbLedWrite(RGB_BUILTIN, 0, RGB_BRIGHTNESS, 0);  // Green
  delay(1000);
  rgbLedWrite(RGB_BUILTIN, 0, 0, RGB_BRIGHTNESS);  // Blue
  delay(1000);
  rgbLedWrite(RGB_BUILTIN, 0, 0, 0);  // Off / black
  delay(1000);
#endif
}

Popcornettay

Re: Blocked ESP32

Postby Popcornettay » Sun Nov 09, 2025 1:50 pm

Yeah I already tried the blink example and some other examples but nothing works. It's just stuck with the neopixel off
Hi,

The red LED is the power LED, so you can't control it via the ESP32-S3. The RGB LED is an addressable LED named SK6812MINI (like WS2812), so you can't control this LED by just toggling the GPIO.

Have you tried the blink example?

Minatel
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Re: Blocked ESP32

Postby Minatel » Mon Nov 10, 2025 8:09 am

Is there any log coming from the UART or USB?

lbernstone
Posts: 1133
Joined: Mon Jul 22, 2019 3:20 pm

Re: Blocked ESP32

Postby lbernstone » Tue Nov 11, 2025 3:20 pm

1) Be sure to use the UART connection to your PC
2) Run `esptool erase_flash` to see if it can be wiped automatically
3) If #2 doesn't work, hold down the boot button (gpio0) when you plug in the device. Then try to erase the flash again

If you have an error in your configuration/code, you may have a boot loop very early in the boot, which prevents the device from being in a state where esptool can get it into download mode. Starting the esp32 in download mode keeps it in a "clean" state where your PC can communicate with it.

Popcornettay

Re: Blocked ESP32

Postby Popcornettay » Tue Nov 11, 2025 9:38 pm

Is there any log coming from the UART or USB?
Yess, I get this when I use the serial monitor. But only when I first connect the card, then I have nothing more comming.

Code: Select all

ESP-ROM:esp32s3-20210327
Build:Mar 27 2021
rst:0x1 (POWERON),boot:0x8 (SPI_FAST_FLASH_BOOT)
SPIWP:0xee
mode:DIO, clock div:1
load:0x3fce2820,len:0x116c
load:0x403c8700,len:0xc2c
load:0x403cb700,len:0x3108
entry 0x403c88b8

Popcornettay

Re: Blocked ESP32

Postby Popcornettay » Tue Nov 11, 2025 9:44 pm

1) Be sure to use the UART connection to your PC
2) Run `esptool erase_flash` to see if it can be wiped automatically
3) If #2 doesn't work, hold down the boot button (gpio0) when you plug in the device. Then try to erase the flash again

If you have an error in your configuration/code, you may have a boot loop very early in the boot, which prevents the device from being in a state where esptool can get it into download mode. Starting the esp32 in download mode keeps it in a "clean" state where your PC can communicate with it.
It doesn't give me any errors when I try to wipe it but I'm still not able to upload anything else on the board. When I try to upload the blink example, it tells me the upload has succeeded but nothing changes on the board. And in the serial monitor I get this message :

Code: Select all

ESP-ROM:esp32s3-20210327
Build:Mar 27 2021
rst:0x1 (POWERON),boot:0x8 (SPI_FAST_FLASH_BOOT)
SPIWP:0xee
mode:DIO, clock div:1
load:0x3fce2820,len:0x116c
load:0x403c8700,len:0xc2c
load:0x403cb700,len:0x3108
entry 0x403c88b8

lbernstone
Posts: 1133
Joined: Mon Jul 22, 2019 3:20 pm

Re: Blocked ESP32

Postby lbernstone » Sat Nov 15, 2025 3:37 am

This looks like a successful boot. If you are still having trouble uploading new code after this, make sure you are using the connection labeled UART, not USB. If you are using Arduino IDE, set the core debug level to verbose and you will get a lot more info about what the device is doing. Paste the following at the top of your file to set the correct pin:

Code: Select all

#define RGB_BUILTIN 38
Pedro, the board has the rgb at io38, but the variant file says 48. Is that correct?

Minatel
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Joined: Mon Jan 04, 2021 2:06 pm

Re: Blocked ESP32

Postby Minatel » Tue Nov 18, 2025 10:47 am

Pedro, the board has the rgb at io38, but the variant file says 48. Is that correct?
For the ESP32-S3-DevKitM-1 the RGB LED is the GPIO48 and for the ESP32-S3-DevKitC-1 the GPIO is the GPIO38.

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