CircuiteraConnect and match the baud rate
Use a supported desktop Web Serial browser, connect the board with a USB data cable, and grant access to the correct port. Open Serial Monitor in the IDE’s bottom panel. Match the monitor baud rate to Serial.begin() in your sketch. For example, Serial.begin(9600) requires a monitor setting of 9600 baud.
Make the sketch report useful information
Add Serial.println() calls for values you want to inspect, such as a sensor reading or the result of a calculation. Give the board time to start after opening the port; some boards reset when the connection opens. If text is garbled, check the baud rate. If nothing appears, confirm that the uploaded sketch actually writes serial output.
Send input and inspect trends
Use the monitor’s input control to send data to a sketch that reads serial input. Choose the line ending expected by the program, particularly when it waits for a newline. For changing numeric values, switch to Serial Plotter and use the formats supported by the current plotter. These tools observe your sketch; they do not change its sensor logic.
Troubleshoot the connection separately
A compile error is different from a missing serial port. If the port is unavailable, close other serial applications and inspect cable and permission problems. Reconnect only when connection state requires it. Browser and operating-system support determine USB availability; reading this guide does not require granting any hardware permissions.