Why UART Prints Garbage: Baud Rate, Voltage Levels, and Ground
Series navigation: Episode 1: The Roadmap · Episode 7: Reading Arduino Pin-Current Specifications · Episode 8 The problem: A terminal shows random symbols even though both devices say “UART.” The goal: Understand what must match electrically and logically before bytes become readable text. The result: A debugging order for TX/RX, ground, voltage, baud rate, frame format, buffering, and signal capture. AI-generated illustration of a low-voltage UART bench. It is not a measurement record or exact wiring guide. The terminal opened, but the text looked broken UART is often the first communication interface I use on a board. It prints boot messages, accepts commands, connects two controllers, or talks to a GPS, modem, Bluetooth module, serial display, or USB-to-serial adapter. Then the terminal shows this: text ��H�l� The program may be sending Hello , but UART does not transmit software strings. It places timed voltage levels on a wire. The receiver must agree about vo...