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Serial Ports

class serial

serial(drvname=SERIAL0, baud=115200, stopbits=STOPBIT_1, parity=PARITY_NONE, bitsize=BITSIZE_8, rxsize=0, txsize=0, mode=MODE_UART, flow_ctrl=HW_FLOWCTRL_DISABLE):

This class implements a stream that can be used to connect to a serial port.

Initialize the serial port driver identified by drivername and starts it up with a baud rate of baud. Additional parameters can be passed such as:

  • parity: PARITY_NONE, PARITY_EVEN, PARITY_ODD
  • stopbits: STOPBIT_1, STOPBIT_1_HALF, STOPBIT_2
  • bitsize: BITSIZE_5, BITSIZE_6, BITSIZE_7, BITSIZE_8
  • rxsize and txsize: the size in bytes of the receive and transmit buffers (0 selects the OS default)
  • mode: MODE_UART, MODE_RS485_HALF_DUPLEX
  • flow_ctrl: HW_FLOWCTRL_DISABLE, HW_FLOWCTRL_RTS, HW_FLOWCTRL_CTS, HW_FLOWCTRL_CTS_RTS

This is the code needed to print something on the default serial port:

import serial

# create a serial stream linked to SERIAL0 port
ser = serial.serial()

# print will output everything to it if passed as stream
print("Hello World!",stream=ser)

method available

available()

Returns the number of characters that can be read without blocking.

method close

close()

Close the serial port.

method write

write(buffer)

Writes the content of buffer to the serial.

buffer must be a byte sequence (bytes, bytearray or string).

Returns the number of bytes actually written to the stream (can be less than the elements in buffer)

method read

read(size=1)

Reads at most size bytes from the serial and returns a bytearray with the actual bytes read.

read blocks if no bytes are available in the stream.

If read returns an empty bytearray the underlying stream can be considered disconnected.

method readline

readline(max_len=256, end="\r\n", with_end=True)

Reads a line from the serial, ending with end marker string, of max_len bytes length, and returns a bytearray with the actual bytes read.

If with_end is True, the returning line contains the end marker as well.