The Raspberry Pi UARTs. In Linux device terms, by default, /dev/ttyS0 refers to the mini UART, and /dev/ttyAMA0 refers to the PL011. The primary UART is the one assigned to the Linux console, which depends on the Raspberry Pi model.
NOTE FOR RASPBERRY PI 3: The Raspberry pi 3 has changed things around a bit: ttyAMA0 now refers to the serial port that is connected to the bluetooth. The old serial port is now called ttyS0. So if you have an RPI3, everywhere you see “ttyAMA0” below, you should read “ttyS0”.
what is ttyUSB0? ttyUSB means “USB serial port adapter” and the “0” (or “1” or whatever) is the device number. ttyUSB0 is the first one found, ttyUSB1 is the second etc. (Note that if you have two similar devices, then the ports that they are plugged into may affected the order they are detected in, and so the names).
Also to know, what is Dev ttyS0?
Serial Port Terminals For each such terminal there is a special file in the /dev (device) directory. /dev/ttyS0 is the special file for the serial port known as COM1 in the DOS/Windows world. To send text to a terminal you may redirect standard output of some command-line command to the appropriate special file.
What is UART in Raspberry Pi?
UART is an asynchronous serial communication protocol, meaning that it takes bytes of data and transmits the individual bits in a sequential fashion. UART is commonly used on the Pi as a convenient way to control it over the GPIO, or access the kernel boot messages from the serial console (enabled by default).