[documentation] ESP32-CAM Board: LED does not light up: wrong LED pin definition?

[dsyleixa]

Related area

esp32-cam

Hardware specification

esp32-cam CAMERA_MODEL_AI_THINKER // Has PSRAM

Is your feature request related to a problem?

the auto-generated website has lot of control widgets, e.g. the LED Intensitiy slider widget.
But when dragging the slider, nothing happens to my onboard-LED, it's always off.
I am using the
#define CAMERA_MODEL_AI_THINKER // Has PSRAM
program: CameraWebServer.ino 2.0.7

testing LED_BUILTIN: not available for CameraWebServer.ino ('LED_BUILTIN' was not declared in this scope)

are there perhaps wrong LED pin definitions in a config file?
Which #defines as to the built-in LED have to be changed probably?
Where can I possibly find documentations about that?

Describe the solution you'd like

correct on-board LED control,
'LED_BUILTIN' was not declared in this scope (CameraWebServer 2.0.7)

Describe alternatives you've considered

No response

Additional context

No response

I have checked existing list of Feature requests and the Contribution Guide

• I confirm I have checked existing list of Feature requests and Contribution Guide.

[Hieromon]

@dsyleixa, The LED pin is GPIO33 of Ai-Thinker ESP32-CAM , which is coupled to the PWM channel. This is not necessarily a mistake.

arduino-esp32/libraries/ESP32/examples/Camera/CameraWebServer/camera_pins.h

Line 158 in 0d84018

#define LED_GPIO_NUM 33

This red LED is placed on the opposite side of the ESP32-CAM from the camera. It is a 1608 LED for signals with less than 100mW output, so you might miss it. And it does change the brightness gracefully according to the LED Intensity in the Settings panel of the Camera Control WebUI.

In fact, my ESP32-CAM changes brightness depending on the LED Intensity value. PWM by ledc is working fine. However, it is far from being a flash LED as the function name suggests.

arduino-esp32/libraries/ESP32/examples/Camera/CameraWebServer/app_httpd.cpp

Lines 1388 to 1391 in 0d84018

	#if CONFIG_LED_ILLUMINATOR_ENABLED
	ledcSetup(LED_LEDC_CHANNEL, 5000, 8);
	ledcAttachPin(pin, LED_LEDC_CHANNEL);
	#else

On the other hand, the connection pin for the other LED equipped by ESP32-CAM (it has a white 1W-class output and is placed on the same side as the camera) is GPIO4.

https://docs.ai-thinker.com/_media/esp32/docs/esp32_cam_sch.pdf

Maybe just change the pin definition to 4 to get the flash LED working as you expect.

#define LED_GPIO_NUM      4
// #define LED_GPIO_NUM      33

But, I do not recommend changing it thoughtlessly. According to the schematic, this flash LED has no resistor (just a transistor for drain current drive according to PWM). VF=3.3V is applied directly. It will probably burn.

In order for you to get this flash LED functionality, I think you should at least do the following:

1. Insert at least a 1K resistor between ANODE of LED_FLASH and 3V3.
2. Change the maximum PWM duty to 127. It defined with CONFIG_LED_MAX_INTENSITY macro in app_httpd.cpp.

And so, I thought it would be better to be at peace with a tiny red LED than to have ESP32-CAM boards burning up all over the world. Of course, this is my personal opinion and is separate from how the maintainer @P-R-O-C-H-Y judges.

[dsyleixa]

thank you very much for your explanations!
In fact, the red on-board LED downside is always on, and it's intensitiy doesn't change by the slider.
Soldering is not possible unfortunately because of certain disablities.
edit:
found app_httpd.cpp also in the local folder, try to patch it and then try GPIO4!

[Hieromon]

@dsyleixa, You are a challenger! Don't forget a glass of water.

[dsyleixa]

what....? :-D
I tried it with pwm 127, but it was way too bright and couldn't even be shut off afterwards by the slider widget.
But now I set it to 32 max, and that looks fine at 1st sight so far... 8-)
thanks a lot! :)

(PS,
would wish to keep this issue open for a couple of days though, in case further problems will arise....)

[dsyleixa]

just observed:
there is already a GPIO4 pin usage:
#define XCLK_GPIO_NUM 4

does that really not matter as to LED_GPIO_NUM 4?

[Hieromon]

@dsyleixa, The XCLK_GPIO_NUM of the Ai-Thinker ESP32-CAM is assigned to Cam_Connector XCLK1. This is GPIO0 and correct.

However, the circuit around the LED_FLASH in ESP32-CAM is inherently problematic. GPIO4 is shared with HS2 DATA1 of Micro SD I/F as well as driving LED_FLASH. In other words, you cannot write to the Micro SD properly with the LED_FLASH applied.

Well, to be more details, there are various other dangers, but don't expect too much from this kind of board.

[dsyleixa]

thank you very much!
Unfortunately I have not much information about all this stuff - especially no easily understandable for me as a hobby programmer. I do not even really see for which purposes the SD would be needed actually

[dsyleixa]

update: module is defective, can be closed.

[NgocLe97]

hi, i have solved this problem,
in file "app_httpd.cpp"

#if CONFIG_LED_ILLUMINATOR_ENABLED

#define LED_LEDC_GPIO 4 //configure LED pin
#define CONFIG_LED_MAX_INTENSITY 255