Lighting Up the LED

Experiment Objective

In this experiment, you will learn how to control the two LEDs on the MicroROS-V2 control board using the ESP-IDF framework. Through this example, you will master the configuration of GPIO output mode, as well as how to turn the LEDs on, off, and make them blink.

Experiment Principle

1. Keywords

2. Technical Architecture

The program uses a foreground/background structure: after initializing the GPIO, it enters the main loop and calls the LED blinking function every 10 ms, toggling the GPIO level to make the LEDs blink. The blue LED blinks with a period of 500 ms and the green LED with a period of 1000 ms. Key files are located in ~/esp/base_samples/led/, including main/main.c (main program entry), components/led/led.h (pin definitions and function declarations) and components/led/led.c (LED driver implementation).

Experiment Steps

1. Hardware Preparation

2. Prerequisites

1. ESP32-IDF development environment set up

2. MicroROS-V2 control board connected to the PC via USB

3. Confirm the two LEDs (green, blue) on the control board are functioning properly

3. Compile and Flash

Use the command below to check the device serial port number,

ls dev/ttyUSB*

Compile,

​x

cd ~/esp/base_samples/led
source ~/esp/esp-idf/export.sh
idf.py build flash monitor

4. How to Stop

Press Ctrl+] in the terminal to exit the serial monitor.

Experiment Result

After compiling and flashing successfully, the serial monitor will output:

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hello yahboom
I (xxx) LED_MAIN: Nice to meet you!

At the same time, the blue LED on the control board blinks with a period of about 1 second (500 ms on, 500 ms off), and the green LED blinks with a period of about 2 seconds (1000 ms on, 1000 ms off).

Code Explanation

Source code paths:

• Firmware source code: ~/esp/base_samples/led/main/main.c

• LED driver: ~/esp/base_samples/led/components/led/led.h, led.c

1. Main Program Logic

main/main.c is the program entry, and the flow is as follows:

1. Print the startup message "hello yahboom" and a welcome log

2. Call Led_Init() to initialize the LED GPIO pins

3. Enter the main loop, executed every 10 ms:

   • The blue LED toggles its state every 500 ms (Led_Blue_Flash(50), interval of 50 × 10 ms), i.e. 500 ms on, 500 ms off

   • The green LED toggles its state every 1000 ms (Led_Green_Flash(100), interval of 100 × 10 ms), i.e. 1000 ms on, 1000 ms off

2. Key Components

components/led/led.h — pin definitions and function declarations:

Parameter definition file: ~/esp/base_samples/led/components/led/led.h

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// GPIO pin definitions
#define LED_GREEN_GPIO           45   // Green LED
#define LED_BLUE_GPIO            48   // Blue LED
#define LED_ACTIVE_LEVEL  1           // Active high to turn on

components/led/led.c — LED driver implementation, with the following core functions:

Initialization process in detail:

Led_Init() uses the gpio_config_t structure to configure the GPIO:

Source file: ~/esp/base_samples/led/components/led/led.c

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gpio_config_t io_conf = {};
io_conf.pin_bit_mask = (1ULL<<45) | (1ULL<<48);  // GPIO45 and GPIO48
io_conf.intr_type = GPIO_INTR_DISABLE;              // Disable interrupt
io_conf.mode = GPIO_MODE_OUTPUT;                    // Output mode
io_conf.pull_down_en = 0;                           // Disable pull-down
io_conf.pull_up_en = 0;                             // Disable pull-up
gpio_config(&io_conf);

Common Problems