Introduction
To use Python as a graphical interface for an Arduino powered robot, programmatically read the USB with the pySerial library. However, waiting for input from pySerial's Serial object is blocking, which means that it will prevent your GUI from being responsive. The process cannot update buttons or react to input because it is busy waiting for the serial to say something.
The first key is to use the root.after(milliseconds) method to run a non-blocking version of read in the tkinter main loop. Keep in mind that when TkInter gets to the root.mainloop() method, it is running its own while loop. It needs the things in there to run every now and then in order to make the interface respond to interactions. If you are running your own infinite loop anywhere in the code, the GUI will freeze up. Alternatively, you could write your own infinite loop, and call root.update() yourself occasionally. Both methods achieve basically the same goal of updating the GUI.
However, the real issue is making sure that reading from serial is non-blocking. Normally, the Serial.read() and Serial.readline() will hold up the whole program until it has enough information to give. For example, a Serial.readline() won't print anything until there is a whole line to return, which in some cases might be never! Even using the after() and update() methods will still not allow the UI to be updated in this case, since the function never ends. This problem can be avoided with the timeout=0 option when enitializing the Serial object, which will cause it to return nothing unless something is already waiting in the Serial object's buffer.
Code
Syntax
Python Pyserial Read Example
Blog post Serial RS232 connections in Python. Import time import serial # configure the serial connections (the parameters differs on the device you are connecting to) ser = serial.Serial( port='/dev/ttyUSB1', baudrate=9600, parity=serial.PARITYODD, stopbits=serial.STOPBITSTWO, bytesize=serial.SEVENBITS ) ser.isOpen print 'Enter your commands below.rnInsert 'exit' to leave. If it ain't broke, I just haven't gotten to it yet. OS: Windows 10, openSuse 42.3, freeBSD 11, Raspian 'Stretch' Python 3.6.5, IDE: PyCharm 2018 Community Edition. Have a look at this Python - Arduino demo Your PC program should open the serial port, allow time for the Arduino to reset before trying to send data and should then keep the serial port open until it is completely finished with the Arduino. Cd /serial sudo python serialread.py. Now in our other terminal window, type in the following two commands to start up the serialwrite.py Python script. Basically, this script will start outputting data through the serial connection which we will soon receive using our other script. Cd /serial sudo python serialwrite.py. Asked Jul 30, 2019 in Python by Eresh Kumar (32.3k points) I have an Arduino connected to my computer running a loop, sending a value over the serial port back to the computer every 100 ms. I want to make a Python script that will read from the serial port only every few seconds, so I want it to just see the last thing sent from the Arduino.
Parameters
| parameter | details |
|---|---|
| port | Device name e.g. /dev/ttyUSB0 on GNU/Linux or COM3 on Windows. |
| baudrate | baudrate type: int default: 9600 standard values: 50, 75, 110, 134, 150, 200, 300, 600, 1200, 1800, 2400, 4800, 9600, 19200, 38400, 57600, 115200 |
Remarks
Check what serial ports are available on your machine
To get a list of available serial ports use
at a command prompt or
from the Python shell.
Python Pyserial Readline Example Java
Initialize serial device
Read from serial port
Initialize serial device
to read single byte from serial device
to read given number of bytes from the serial device
to read one line from serial device.
to read the data from serial device while something is being written over it.