Power and operation essentials Power source selection: Do not connect USB when an external power supply is used. You can only choose one power source at a time (USB or external). This prevents conflicts and protects the board. Entering download mode on ESP32C3: To enter download mode, press and hold the BOOT key on the ESP32C3, then press the RESET key. Release the RESET key first, then release the BOOT key. The ESP32C3 will enter download mode. Reenter download mode on each connection: You may need to reenter download mode every time you connect. The USB port can be unstable and may disconnect after a single press. You can confirm connection status by the port recognition sound. External power connection (when required): If external power is required, connect the external power supply positive lead to the 5V pin and the ground lead to GND. The board supports a supply range from 3.3 to 6V. Compatibility and performance highlights Target device: ESP32C3 compatible interface and boot workflow. Simple power options: Flexible between USB power and external 3.36V power supply, with explicit singlesource operation. Clear boot procedure: Stepbystep instructions to reliably enter download mode for firmware flashing. Connection reliability cue: Port recognition sound helps verify proper connection after each action. Use scenarios Development and firmware flashing: Connect via USB or an external 5V supply to flash ESP32C3 firmware. Use the defined boot and reset sequence to access download mode when needed. Debugging in environments with unreliable USB: Use a dedicated external power supply to maintain stable power while flashing or testing, and reenter download mode as required. Field testing and portable setups: When a regulated power source is available, use the 5V and GND connections to power the ESP32C3, ensuring consistent operation and easy reentry into download mode during development.