BlinkRGB.ino example code for ESP32 C3 is not correct

daledj · December 16, 2023, 2:56am

The example code for ESP32 for BlinkRGB.ino shows and example for

digitalWrite(RGB_BUILTIN, HIGH); // Turn the RGB LED white

This code does not work with the board type Lolin ESP32 C3 mini. It appears that the library is incorrect and this is not supported. There is some discussion about this in the espressif forums indicating that a new version is available.

The BlinkRGB.ino example is part of the library package for the ESP32 boards. It is not in a library that I've added using the Board Manager.

MaximoEsfuerzo · December 16, 2023, 4:31am

Lolin is not Arduino.
Report the issue to the Espressif's guys, they are the authors of the ESP32 core and everything related to it.

Regards

ptillisch · December 16, 2023, 9:35am

Hi @daledj. The "esp32" boards platform supports hundreds of boards, with very significant differences between each. Some of the libraries and example sketches bundled with the platform are only compatible with a subset of the supported boards.

I think this is communicated reasonably well in the example sketch:

https://github.com/espressif/arduino-esp32/blob/2.0.14/libraries/ESP32/examples/GPIO/BlinkRGB/BlinkRGB.ino#L4

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

It is not accurate to say these are "not correct". What is not correct is attempting to use the sketch or library with a board it was not intended to be used with.

Does your "Lolin ESP32 C3 mini" board have an onboard RBG led?

sterretje · December 16, 2023, 10:19am

It should See Documentation Error for neopixelWrite() that states that OP gets the wrong colours.

al1fch · December 16, 2023, 12:00pm

Hi

Lolin C3 Mini.... wich version ?

V1.0.0 has a simple led on GPIO7 (and bad antenna design )
https://www.wemos.cc/en/latest/c3/c3_mini_1_0_0.html

V2.1.0 has a WS2812 en GPIO7
https://www.wemos.cc/en/latest/c3/c3_mini.html

daledj · December 16, 2023, 2:05pm

I will report on espressif forum. Yes, my board which is a LOLIN ESP32 C3 Pico does have the color LED. I'm using the board type for LOLIN ESP32 C3 mini, because there is no Pico board type, but from what I can read the boards are equivalent, but the Pico has a battery input and charger on the board.

ptillisch · December 16, 2023, 3:12pm

The "esp32" boards platform is interesting in that the maintainers accept the addition of support for any ESP32-based board by anyone. The developers of the platform don't own all these boards and wouldn't have the time to run tests on all that hardware even if they did. So the idea seems to be that the maintenance of the board-specific code is the responsibility of the people who need that code (the board manufacturer and the users of the board). The platform developers only worry about the code that supports all boards generally and the general purpose "Dev Module" type of board definitions.

So when a new capability is added to the platform code, it is expected that someone will later come along to update the board-specific code to take advantage of the new capability. That is the case here. When the support for boards with built-in addressable RGB LEDs was added, the developers only updated the "Dev Module" board definitions:

github.com/espressif/arduino-esp32

Improve RGB driver in pull #6808; solves #6968

espressif:master ← santaimpersonator:master

opened 04:18PM - 12 Jul 22 UTC

santaimpersonator

+27 -27

## Description of Change This solution adds a `RGB_BUILTIN` variable to pull re…quest https://github.com/espressif/arduino-esp32/pull/6808. With the original solution (https://github.com/espressif/arduino-esp32/pull/6808), users were limited to controlling a single built-in LED. By creating a new variable `RGB_BUILTIN`, users are able to control a regular LED and RGB LED with the `digitalWrite()` function, separately from each other. * Replaces the use of the `LED_BUILTIN` variable for the RGB LED * Removes the need for `BOARD_HAS_NEOPIXEL` * Also, renames `LED_BRIGHTNESS` to match new variable name `RGB_BRIGHTNESS` For boards that have a regular LED and RGB LED on their board, users can define the pin configuration *(below)* and the `Blink.ino` and `BlinkRGB.ino` example sketches would operate on the regular and RGB LEDs separately. ``` static const uint8_t LED_BUILTIN = 13; static const uint8_t RGB_BUILTIN = SOC_GPIO_PIN_COUNT+2; #define BUILTIN_LED LED_BUILTIN // backward compatibility #define LED_BUILTIN LED_BUILTIN #define RGB_BUILTIN RGB_BUILTIN #define RGB_BRIGHTNESS 65 ``` ## Tests scenarios I have tested the proposed changes with the regular [`Blink.ino`](https://github.com/arduino/Arduino/blob/master/app/testdata/sketches/Blink/Blink.ino) and the **ESP32**>**GPIO**>[`BlinkRGB.ino`](https://github.com/espressif/arduino-esp32/blob/master/libraries/ESP32/examples/GPIO/BlinkRGB/BlinkRGB.ino) example sketches. These tests were performed on an ESP32-WROOM board with a regular LED and RGB LED. The sketches were also tested for the following pin configurations: * Regular and RGB LED: * `Blink.ino` only controls regular LED * `BlinkRGB.ino` only controls the RGB LED ``` static const uint8_t LED_BUILTIN = 13; static const uint8_t RGB_BUILTIN = SOC_GPIO_PIN_COUNT+2; #define BUILTIN_LED LED_BUILTIN // backward compatibility #define LED_BUILTIN LED_BUILTIN #define RGB_BUILTIN RGB_BUILTIN #define RGB_BRIGHTNESS 65 ``` * Only RGB LED: * `Blink.ino` and `BlinkRGB.ino` both control the RGB LED ``` static const uint8_t LED_BUILTIN = SOC_GPIO_PIN_COUNT+2; #define BUILTIN_LED LED_BUILTIN // backward compatibility #define LED_BUILTIN LED_BUILTIN #define RGB_BUILTIN LED_BUILTIN #define RGB_BRIGHTNESS 65 ``` * Only regular LED: * Only `Blink.ino` works with the regular LED ``` static const uint8_t LED_BUILTIN = 13; #define BUILTIN_LED LED_BUILTIN // backward compatibility #define LED_BUILTIN LED_BUILTIN ``` ## Related links Closes https://github.com/espressif/arduino-esp32/issues/6968 *\*Based on original pull request (https://github.com/espressif/arduino-esp32/pull/6808) and issue (https://github.com/espressif/arduino-esp32/issues/6783)*

Since that time, contributors have added support for various other boards, but nobody happened to do it for the lolin_c3_mini core variant used by the "LOLIN C3 Mini" board definition. So the RGB_BUILTIN macro is not defined when you have this board selected:

github.com

espressif/arduino-esp32/blob/2.0.14/variants/lolin_c3_mini/pins_arduino.h

#ifndef Pins_Arduino_h
#define Pins_Arduino_h

#include <stdint.h>

#define EXTERNAL_NUM_INTERRUPTS 22
#define NUM_DIGITAL_PINS        22
#define NUM_ANALOG_INPUTS       6

#define analogInputToDigitalPin(p)  (((p)<NUM_ANALOG_INPUTS)?(analogChannelToDigitalPin(p)):-1)
#define digitalPinToInterrupt(p)    (((p)<NUM_DIGITAL_PINS)?(p):-1)
#define digitalPinHasPWM(p)         (p < EXTERNAL_NUM_INTERRUPTS)

static const uint8_t LED_BUILTIN = 7;
#define BUILTIN_LED  LED_BUILTIN // backward compatibility

static const uint8_t TX = 21;
static const uint8_t RX = 20;

static const uint8_t SDA = 8;

This file has been truncated. show original

But you can use the sketch even though the RGB_BUILTIN macro isn't pre-defined for your board. Just add this line to the top of the sketch:

#define RGB_BUILTIN 7

Yeah, I see from the schematics that the RGB LED's data pin is connected to IO7 on both boards.

system · June 13, 2024, 3:12pm

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BlinkRGB.ino example code for ESP32 C3 is not correct

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