Chapter 7 Serial Communication

Serial Communication is a means of communication between different devices/devices. This section describes ESP32-S3’s Serial Communication

Project 7.1 Serial Print

This project uses ESP32-S3’s serial communicator to send data to the computer and

print it on the serial monitor.

Component List

ESP32-S3-WROOM x1
GPIO Extension Board x1
Type C USB Cable x1

Connect

Connect ESP32-S3 to the computer with USB cable.

Sketch

Sketch_07.1_SerialPrinter

Download the code to ESP32-S3 WROOM, open the serial port monitor, set the baud rate to 115200, and press the reset button. As shown in the following figure:

Code

The following is the program code:

void setup() {
Serial.begin(115200);
Serial.println("ESP32S3 initialization completed!");
}

void loop() {
Serial.printf("Running time : %.1f s\r\n", millis() / 1000.0f);
delay(1000);
}

Project 7.2 Serial Read and Write

From last section, we use serial port on ESP32-S3 to send data to a com puter, now we will use that to receive data from computer.

Component and circuit are the same as in the previous project.

Sketch

Sketch_07.2_SerialRW

Download the code to ESP32-S3 WROOM, open the serial monitor, and set the top right corner to Newline, 115200. As shown in the following figure:

Then type characters like ‘ABCDEFG’ into the data sent at the top, and press Ctrl+Enter to send the message.

Code

The following is the program code:

String inputString = "";      //a String to hold incoming data
bool stringComplete = false;  // whether the string is complete

void setup() {
Serial.begin(115200);
Serial.println(String("\nESP32S3 initialization completed!\r\n")
                + String("Please input some characters,\r\n")
                + String("select \"Newline\" below and Ctrl + Enter to send message to ESP32S3. \r\n"));
}

void loop() {
if (Serial.available()) {         // judge whether data has been received
    char inChar = Serial.read();         // read one character
    inputString += inChar;
    if (inChar == '\n') {
    stringComplete = true;
    }
}
if (stringComplete) {
    Serial.printf("inputString: %s \r\n", inputString);
    inputString = "";
    stringComplete = false;
}
}

In loop(), determine whether the serial port has data, if so, read and save the data, and if the newline character is read, print out all the data that has been read.