Serial communication with Python
Contents
Serial communication with Python¶
Part of a project I am working on using micro-controllers is being able to efficiently and quickly communicate data backwards and forwards across the serial ports. The python package
pip install pyserial
provides an abstraction that allows this task to be completed with ease.
Table of Contents¶
Synchronous interaction¶
Reading and writing to a serial port is pretty straight forward with serial. We can begin instantiate and open a connection with
import serial
ser = serial.Serial(
port = DEV_PORT,
baudrate = BAUD_RATE,
timeout=0.1
)
The timeout is in seconds, representing the wait time for read() invocations, before releasing the block. write() is blocking by default, unless the write_timeout is set to True.
When opening a connection with a MCU, the RTS (ready to send) and DTR (data terminal ready) signals are sent. For arduinos, by default, these signals will reset the current script running.
Reading¶
The idiom for reading from the serial port is much like the idiom used in the arduino script; i.e., while there is data, read. We can implement this as
while ser.inWaiting() > 0: # number of bytes in waiting
inp = ser.read(ser.inWaiting()).decode()
if inp != '':
# do something with input
Writing¶
When writing to the serial port, it can be of importance to wait until the written data is consumed. The ser.flush() method can facilitate this.
Writing to an open port is as easy as
ser.write("string".encode())