The Raspberry Pi™ serial port provides low speed +3.3V TTL RS-232 data communication with a wide variety of devices, such as sensors, displays, ADCs, and DACs. The serial port UART connects to two pins on the GPIO header:
GPIO 14 (UART0_TXD) transmits data
to the RxD pin on the peripheral device.
GPIO 15 (UART0_RXD) receives data
from the TxD pin on the peripheral device.
By default, the serial console in the customized version of Raspbian Linux® on your Raspberry Pi hardware is disabled. To use the serialdev, the serial
console must be disabled.
For more information, see:
Do not connect the Raspberry Pi serial port to 12V RS-232 serial ports, which are found on many older computers.