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
Turn off the UART bus.
Read characters. If
nbytesis specified then read at most that many bytes. If
nbytesare available in the buffer, returns immediately, otherwise returns when sufficient characters arrive or the timeout elapses.
Read as much data as possible. Returns after the timeout has elapsed.
Return value: a bytes object or
Noneif timeout prevents any data being read.
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. If such a line exists, return is immediate. If the timeout elapses, all available data is returned regardless of whether a newline exists.
Return value: the line read or
Noneon timeout if no data is available.
Send a break condition on the bus. This drives the bus low for a duration of 13 bits. Return value: