class UART – duplex serial communication bus

UART implements the standard UART/USART duplex serial communications protocol. At the physical level it consists of 2 lines: RX and TX. The unit of communication is a character (not to be confused with a string character) which can be 8 or 9 bits wide.

UART objects can be created and initialised using:

from pyb import UART

uart = UART(1, 9600)                         # init with given baudrate
uart.init(9600, bits=8, parity=None, stop=1) # init with given parameters

A UART object acts like a stream object and reading and writing is done using the standard stream methods:

uart.read(10)       # read 10 characters, returns a bytes object
uart.readall()      # read all available characters
uart.readline()     # read a line
uart.readinto(buf)  # read and store into the given buffer
uart.write('abc')   # write the 3 characters

Individual characters can be read/written using:

uart.readchar()     # read 1 character and returns it as an integer
uart.writechar(42)  # write 1 character

To check if there is anything to be read, use:

uart.any()               # returns True if any characters waiting

Note: The stream functions read, write, etc. are new in MicroPython v1.3.4. Earlier versions use uart.send and uart.recv.

Constructors

Methods

uart.deinit()

Turn off the UART bus.

uart.any()

Return True if any characters waiting, else False.

uart.read([nbytes])

Read characters. If nbytes is specified then read at most that many bytes.

uart.readall()

Read as much data as possible.

Return value: a bytes object.

uart.readchar()

Receive a single character on the bus.

Return value: The character read, as an integer. Returns -1 on timeout.

uart.readinto(buf[, nbytes])

Read bytes into the buf. If nbytes is specified then read at most that many bytes. Otherwise, read at most len(buf) bytes.

Return value: number of bytes read and stored into buf.

uart.readline()

Read a line, ending in a newline character.

Return value: the line read.

uart.write(buf)

uart.writechar(char)

Write a single character on the bus. char is an integer to write. Return value: None.

uart.sendbreak()

Send a break condition on the bus. This drives the bus low for a duration of 13 bits. Return value: None.

Constants

UART.RTS

UART.CTS

to select the flow control type