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
write, etc. are new in MicroPython v1.3.4.
Earlier versions use
Turn off the UART bus.
Trueif any characters waiting, else
Read characters. If
nbytesis specified then read at most that many bytes.
Read as much data as possible.
Return value: a bytes object.
Receive a single character on the bus.
Return value: The character read, as an integer. Returns -1 on timeout.
Read bytes into the
nbytesis specified then read at most that many bytes. Otherwise, read at most
Return value: number of bytes read and stored into
Read a line, ending in a newline character.
Return value: the line read.
Write a single character on the bus.
charis an integer to write. Return value:
Send a break condition on the bus. This drives the bus low for a duration of 13 bits. Return value: