Lesson01_Serial_Communication: Serial Output of Hello World¶
1. Course Introduction¶
This lesson uses the ESP32-S3 USB serial interface to initialize serial communication at 115200 bit/s, output Hello World once immediately after the device starts, and then repeat the output approximately every 1 second. Learners will open the project, compile and upload it, and observe the Serial Monitor, establishing the serial debugging methods required for subsequent lessons.
2. Learning Objectives¶
- Select the ESP32-S3 development board and the correct serial port in the Arduino IDE.
- Explain the relationship between
Serial.begin(115200)and the baud rate of the Serial Monitor. - Compile and upload the program, and determine whether the startup output and periodic output are normal.
3. Preparation¶
- One ESP32-S3 2.1-inch development board.
- One USB cable that supports data transfer; connect it to the board's native USB/serial interface.
- Arduino IDE (version to be supplemented based on the actual environment) and ESP32 Arduino Core (version to be supplemented).
- Project file
/Examples/2.1_Lesson01-Print_Hello_World/Lesson01-Print_Hello_World.ino.
Code download link: https://github.com/Elecrow-RD/CrowPanel-2.1inch-HMI-ESP32-Rotary-Display-480-480-IPS-Round-Touch-Knob-Screen/tree/master/example/Arduino/Examples/
4. Software Operation Steps¶
When using the board for the first time, complete the configuration in the order described in this section. First confirm the development environment and project, then connect the hardware, select the board and port, and finally compile and upload.
4.1 Confirm the Arduino IDE Version¶
Launch the Arduino IDE, open Help > About Arduino IDE, and confirm that you are using Arduino IDE 2.x. The version number shown in the screenshot is for demonstration only, and does not need to match the screenshot exactly.
Software installation: Download_Arduino_IDE - Elecrow Wiki
4.2 Install the ESP32 Board Support Package¶
After the installation is completed, open the Arduino IDE. First, randomly open a project.
Go to "Preferences"
Configure "Additional Boards Manager URLs"
Add this in
https://jihulab.com/esp-mirror/espressif/arduino-esp32/-/raw/gh-pages/package_esp32_index_cn.json
Remember to save!
- Click Board Manager on the left side.
- Search for
esp32. - Locate esp32 by Espressif Systems, select the version required by the course, and install it.
- After installation, close the Board Manager; if the corresponding version already shows as
installed, there is no need to reinstall.
The reference image shows the entry point, search, and version status of the Board Manager. For this P4 lesson, version 3.3.8 should be installed.
4.3 Create or Open the Complete Project¶
In the Arduino IDE, select File > New Sketch and save it as Lesson01-Print_Hello_World; alternatively, you can directly open Lesson01-Print_Hello_World.ino from the course code.
An Arduino sketch requires the project folder name to match the main .ino file name. For example:
If the IDE prompts you to automatically create a folder with the same name, confirm and proceed.
Write the following code into the sketch and save it:
void setup() {
Serial.begin(115200);
delay(300);
Serial.println("Hello World");
}
/**
* @brief Print a heartbeat message at a readable interval.
*
* @return Nothing.
* @note Called repeatedly by the Arduino framework.
*/
void loop() {
delay(1000);
Serial.println("Hello World");
}
4.4 Connect the Board Using USB¶
Connect a USB-C cable that supports data transfer to the port labeled USBoard, then connect it to your computer.
4.5 Select the Board and Port¶
Open Tools > Board > esp32 and select ESP32S3 Dev Module.
Then open Tools > Port and select the COM port that newly appears after connecting the board. If you are unsure which port to choose, unplug the data cable to observe which port disappears, then reconnect and select the port that reappears.
4.6 Verify the Upload Parameters¶
Check each item in the Tools menu:
- Board:
ESP32S3 Dev Module - USB CDC On Boot: "Enabled"
- Flash Mode: QIO
80MHz - Flash Size:
16MB (128Mb) - Partition Scheme:
elecrow_s3 (10.0MB APP with OTA/1.31MB SPIFFS) - PSRAM: "OPI PSRAM"
- Upload Mode:
UART0 / Hardware CDC - USB Mode:
Hardware CDC and JTAG - Port: the
COMport that actually corresponds to the board
4.7 Import the Library Files We Need to Use¶
Open File > Preferences and note the "Sketchbook location".
Close the Arduino IDE, then confirm that the libraries folder exists in that directory.
Library file link for this project: https://github.com/Elecrow-RD/CrowPanel-2.1inch-HMI-ESP32-Rotary-Display-480-480-IPS-Round-Touch-Knob-Screen/tree/master/example/Arduino/Examples/
After determining the location where the library files are stored Copy all the library files contained in the downloaded "libraries" file to the "C:\Users\Username\Documents\Arduino\libraries" folder on your local computer.
How to add the library files: https://www.elecrow.com/wiki/Arduino_IDE_Library_Import_Guide.html
Note: The course dependency libraries need to be placed in the libraries directory under the Arduino Sketchbook folder. After copying is complete, restart the Arduino IDE to prevent the IDE from continuing to use the old library index.
Note: If there is no "libraries" folder in your path, please create one yourself.
4.8 Verify Compilation Before Uploading¶
- Click the Verify (checkmark) button in the upper left corner.
- Wait for the output area to show that compilation is complete; if errors appear, resolve them first and do not upload directly.
- Click the Upload (right arrow) button.
- Wait until writing reaches 100%, and see the upload complete or auto-reset message.
If it stays stuck at Connecting... for a long time, first confirm the UART0 connection, the data cable, and the COM port; if it still cannot connect, hold down the BOOT button on the board and release it once writing begins.
4.9 Open the Serial Monitor to Verify the Result¶
Click the Serial Monitor in the upper right corner and set the baud rate to 115200. The baud rate must match Serial.begin(115200).
Under normal conditions, the monitor will continuously display:
Adjacent lines are spaced about 1 second apart.
5. Hardware Operation Steps¶
- With the power off, check that the USB cable is securely connected, then connect the development board to the computer. Use an interface that supports data transfer; do not use a charge-only cable.
- After the upload is complete, wait for the development board to reset and observe the first
Hello Worldin the Serial Monitor.
6. Explanation of Key Code¶
void setup() { Serial.begin(115200); delay(300); Serial.println("Hello World"); }
void loop() { delay(1000); Serial.println("Hello World"); }
setup()executes only once after power-on or reset.Serial.begin(115200)configures the serial communication speed. The Serial Monitor must use the same speed; otherwise, garbled text will appear.delay(300)provides a short interval for the USB serial connection to initialize and the monitor to open. The program will usually still run if it is removed, but the earliest startup message may be missed.loop()executes repeatedly. It outputs once after a 1000 ms delay, so during stable operation there should be approximately one line per second.- When
115200is changed to another value, the Serial Monitor must be changed accordingly. Modifying only one side will result in garbled text. Changingdelay(1000)todelay(200)produces a higher output frequency, but logs should not be sent too densely for extended periods.
7. Experimental Results¶
After uploading and resetting, the Serial Monitor should display Hello World at a baud rate of 115200. The program then outputs one line of the same text approximately every 1 second. If there is no output, first check the serial port number, the monitor baud rate, whether the USB cable supports data transfer, and whether the development board has been reset.