09 - No Serial Output

# Understanding ESP32 USB CDC with Arduino IDE The ESP32-S3's USB CDC (Communication Device Class) feature allows it to act as a virtual serial port over USB, eliminating the need for an external UART-to-USB converter. This is ideal for debugging or sending data to a PC, appearing as a COM port (e.g., `COMx` on Windows or `/dev/ttyACM0` on Linux). However, misconfiguration can lead to issues, such as seeing boot messages but no serial output from your code. This article explains how to configure USB CDC in Arduino IDE and provides a sample sketch to get you started. ## Why No Serial Output?  If you see the ESP32-S3 boot log but no output from your code, the USB CDC setting might be wrong, or your code might be using the wrong serial interface (e.g., `Serial1` instead of `Serial`). To use USB CDC, you must enable it in Arduino IDE and ensure your code writes to the correct port. or if you uses UART port, the USB CDC should be disabled. ## Using Right Type-C Port  1. **Enable USB CDC**: - In Arduino IDE, go to `Tools > USB CDC On Boot` and select **Enabled**. This ensures the ESP32-S3 uses USB (Right Port) for serial communication. 2. **Select the Correct Board**: - Choose your ESP32-S3 board under `Tools > Board` (e.g., "ESP32S3 Dev Module"). 3. **Use `Serial` for USB CDC**: - In your sketch, use `Serial` (not `Serial1` or `Serial2`) to send data over USB CDC. 4. **Set Baud Rate**: - Match the baud rate in `Serial.begin()` with your Serial Monitor settings (e.g., 115200). ## Using the Left UART Port 1. **Disable USB CDC**: - In Arduino IDE, go to `Tools > USB CDC On Boot` and select **Enabled**. This ensures the ESP32-S3 uses UART for serial communication. The rest configurations are the same as above. ## Sample Code Below is a simple sketch to test Serial Output on an ESP32-S3: ```cpp void setup() { Serial.begin(115200); // Initialize USB CDC serial at 115200 baud delay(1000); // Wait for serial connection } void loop() { Serial.println("Hello from ESP32-S3"); delay(1000); // Print every second } ``` ## Troubleshooting Tips - **No Output?** If you uses Right Type-C (USB) port, verify `USB CDC On Boot` is enabled and the correct COM port is selected in the Serial Monitor. - **Using UART Instead?** If using a physical UART port (Left Type-C), disable USB CDC in `Tools > USB CDC On Boot` and use `Serial1` or `Serial2` for the UART pins. - **Driver Issues?** Ensure your PC recognizes the ESP32-S3 as a COM port. Install drivers if needed (e.g., CP2102 drivers for Windows). ## Key Notes - **USB CDC**: Use for USB-based serial communication. Enable it in Arduino IDE for application output. - **UART**: Use for external serial converters. Disable USB CDC to avoid conflicts. - **Baud Rate**: Ensure it matches between your code and Serial Monitor. This setup ensures reliable serial communication for debugging or data transfer with your ESP32-S3.