Troubleshooting Serial Connections

Nothing but gibberish on your screen? Connection timing out? This guide walks you through the most common serial communication problems and how to solve them.

Problem 1: Garbled Text (e.g., "")

This is the most common issue and is almost always caused by a baud rate mismatch.

Solution: Ensure the baud rate in your terminal software is set to the exact same value that the device's firmware is configured for. Cycle through common baud rates (9600, 115200, etc.) until you see readable text.

Problem 2: No Data at All

You've connected, but the screen is blank. This could be a few things.

Wiring: Double-check your connections. A common mistake is swapping the TX (transmit) and RX (receive) lines. The TX of one device should go to the RX of the other, and vice-versa.
Correct Port: Are you sure you've connected to the right COM port? Unplug and replug the device to see which port disappears and reappears in your device manager or terminal list.
Device Not Sending: Is the device actually programmed to send data? Ensure its code includes logic to print to the serial line.
Drivers: Some USB-to-serial chips (like CH340, CP210x) require specific drivers to be installed on your operating system.

Problem 3: Can't Open Port

The terminal gives you an error like "Port busy" or "Access denied".

Another Program is Using It: Only one program can have a serial port open at a time. Make sure you've closed other terminals, Arduino IDE's Serial Monitor, or any other software that might be holding the port open.
Permissions: On Linux and macOS, you may need to be part of a specific group (like dialout or uucp) to have permissions to access serial ports. A quick search for your OS and "serial port permissions" will guide you.