从 PyQt GUI 连接到串口 [英] Connect to serial from a PyQt GUI

问题描述

我编写了一个程序来从串行发送和接收数据，但是我有一个问题，我想创建一个函数connect()"或一个类，当我按下一个按钮时，该函数被执行，但是如果我在MainWindow"类中创建这个函数，TestThread"类中的变量ser"未初始化，你能帮我吗?

I write a program to that send and recive data from serial, but I have a problem, I want to create a function "connect()" or a class, and when I press a button, the function is executed, but if I create this function in "MainWindow" class, variable "ser" from "TestThread" class become uninitialized, can you help me?

import sys
import serial


from PyQt5.QtWidgets import QMainWindow, QApplication
from PyQt5.QtCore import QThread, pyqtSignal
from PyQt5.uic import loadUi


ser = serial.Serial('/dev/tty.usbmodem14201', 9600, timeout=1)

class TestThread(QThread):
    serialUpdate = pyqtSignal(str)
    def run(self):
        while ser.is_open:
            QThread.sleep(1)
            value = ser.readline().decode('ascii')
            self.serialUpdate.emit(value)
            ser.flush()

class MainWindow(QMainWindow):
    def __init__(self):
        super(MainWindow, self).__init__()
        loadUi('/Users/bogdanvesa/P2A_GUI/mainwindow.ui', self)
        self.thread = TestThread(self)
        self.thread.serialUpdate.connect(self.handleSerialUpdate)

        self.connect_btn.clicked.connect(self.connectSer)
        self.lcd_EBtn.clicked.connect(self.startThread)

    def startThread(self):
        self.thread.start()

    def handleSerialUpdate(self, value):
        print(value)
        self.lcd_lineEdit.setText(value)


def main():

    app = QApplication(sys.argv)
    form = MainWindow()
    form.show()
    sys.exit(app.exec_())

if __name__ == "__main__":
    main()

推荐答案

与其使用 pySerial + thread，不如使用与 Qt 事件循环一起使用的 QSerialPort:>

Instead of using pySerial + thread it is better to use QSerialPort that is made to live with the Qt event-loop:

from PyQt5 import QtCore, QtWidgets, QtSerialPort

class Widget(QtWidgets.QWidget):
    def __init__(self, parent=None):
        super(Widget, self).__init__(parent)
        self.message_le = QtWidgets.QLineEdit()
        self.send_btn = QtWidgets.QPushButton(
            text="Send",
            clicked=self.send
        )
        self.output_te = QtWidgets.QTextEdit(readOnly=True)
        self.button = QtWidgets.QPushButton(
            text="Connect", 
            checkable=True,
            toggled=self.on_toggled
        )
        lay = QtWidgets.QVBoxLayout(self)
        hlay = QtWidgets.QHBoxLayout()
        hlay.addWidget(self.message_le)
        hlay.addWidget(self.send_btn)
        lay.addLayout(hlay)
        lay.addWidget(self.output_te)
        lay.addWidget(self.button)

        self.serial = QtSerialPort.QSerialPort(
            '/dev/tty.usbmodem14201',
            baudRate=QtSerialPort.QSerialPort.Baud9600,
            readyRead=self.receive
        )

    @QtCore.pyqtSlot()
    def receive(self):
        while self.serial.canReadLine():
            text = self.serial.readLine().data().decode()
            text = text.rstrip('\r\n')
            self.output_te.append(text)

    @QtCore.pyqtSlot()
    def send(self):
        self.serial.write(self.message_le.text().encode())

    @QtCore.pyqtSlot(bool)
    def on_toggled(self, checked):
        self.button.setText("Disconnect" if checked else "Connect")
        if checked:
            if not self.serial.isOpen():
                if not self.serial.open(QtCore.QIODevice.ReadWrite):
                    self.button.setChecked(False)
        else:
            self.serial.close()

if __name__ == '__main__':
    import sys
    app = QtWidgets.QApplication(sys.argv)
    w = Widget()
    w.show()
    sys.exit(app.exec_())

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