UART-to-TTL adapter

Theory

A UART-to-TTL adapter is used to interface with UART communication ports, commonly found in embedded systems, by converting TTL (3.3V or 5V) signals to USB for interaction with a computer. The UART protocol uses three key pins: TX (Transmit), RX (Receive), and GND (Ground). The TX pin sends data from the device, RX receives data, and GND ensures a common reference for signal integrity. Correctly matching voltage levels (3.3V or 5V) between the adapter and the target device is crucial to prevent damage during communication.

Usage

• Open your serial terminal software and configure the following settings:

  • Baud Rate: Most popular values are 9600 and 115200, or as specified in the device’s documentation (picocom also has a feature to adjust the baud rate on the fly (check docs)).

    • more common baud rates: 4800, 19200, 38400, 57600, 230400, 460800, 921600

• There are more settings you have to figure out, but the most common ones are these:

  • Data Bits: 8

  • Parity: None

  • Stop Bits: 1

  • Flow Control: None

Linux

sudo minicom -D /dev/ttyUSB0 -b 115200
sudo picocom -b 115200 -r -l /dev/ttyUSB0

Windows

Using PuTTY (Windows):

• Select “Serial” and enter the COM port (e.g., COM3) and baud rate (115200).

UART-TTL adapter are usually pretty cheap ($10) and compact like this model:

FT232-AZ USB to TTL serial adapter

Hint:

If you console looks like this, you probably have the wrong baud rate set:

False baud rate set

Resources

• RS232 vs TTL: Beginner Guide to Serial Communication