所有线程均未与QThread以及QtSerialPort对于Arduino和Matplotlib一起运行

编程问答 2022-08-16

问题描述

我正在尝试从arduino获取输出，以在两个pyqt窗口中进行更新，其中一个是matplotlib图。如果我注释掉非绘图线程窗口，则绘图有效。但是当我尝试同时运行两者时，我收到消息

ActiveRecord::Schema.define(version: 2020_08_17_190727) do

  create_table "item_instances",options: "ENGINE=InnoDB DEFAULT CHARSET=latin1",force: :cascade do |t|
    t.integer "inv_number"
    t.string "serial"
    t.integer "po_number"
    t.date "po_date"
    t.date "invoice"
    t.date "date_out"
    t.decimal "cost",precision: 8,scale: 2
    t.string "acro"
    t.datetime "created_at",null: false
    t.datetime "updated_at",null: false
    t.bigint "item_id"
    t.index ["item_id"],name: "fk_rails_6ea33fd9d0"
  end

  create_table "items",force: :cascade do |t|
    t.string "description"
    t.decimal "cost",scale: 2
    t.decimal "list_price",scale: 2
    t.datetime "created_at",null: false
    t.boolean "active"
  end

  add_foreign_key "item_instances","items"
end

但是，尽管有窗口，但图中未显示任何内容。非图窗口将使用值进行更新。我不确定是否应该使用QThreadpool而不是QThread。附带说明，如果我尝试重新运行代码，则会收到消息

3 Device is already open
3 Device is already open

因此，在再次运行python脚本之前，我必须拔下并重新插入arduino，再次上传其代码，并且两个窗口均未更新值。 我使用的arduino代码只是在1秒的时间间隔内发出信号以进行测试，

2 Access is denied.
2 Access is denied.
2 Access is denied.

引脚13连接到arduino上的A0的位置。 python代码是

int PinOutput = 13;
int PinInput = A0;
int inph;
int inpl;

void setup() {
  // put your setup code here,to run once:
Serial.begin(9600);
pinMode(PinInput,INPUT);
pinMode(PinOutput,OUTPUT);

}

void loop() {
  // put your main code here,to run repeatedly:
inpl = analogRead(PinInput)/4;
Serial.println(inpl);
analogWrite(PinOutput,255);
delay(1000);
inph = analogRead(PinInput)/4;
Serial.println(inph);
analogWrite(PinOutput,0);
delay(1000);
}

因此，我正在尝试使arduino输出全局可用，然后供不同线程同时使用，并在两个窗口中进行更新，其中一个带有绘图。有关如何执行此操作的任何信息都会有所帮助，谢谢。

解决方法

我假设OP正在使用my old answer，并且在该解决方案中表明使用QSerialPort避免了不必要的线程使用，在这种情况下也是如此。另一方面，串行端口不能由多个类处理。在这种情况下，您只需要创建一个管理串行端口并将信息分发到其他元素的类即可。

import sys

from PyQt5 import QtCore,QtWidgets,QtSerialPort

from matplotlib.figure import Figure
from matplotlib.backends.backend_qt5agg import FigureCanvasQTAgg


class Ui_MainWindow(object):
    def setupUi(self,MainWindow):
        MainWindow.setObjectName("MainWindow")
        MainWindow.resize(325,237)
        self.centralwidget = QtWidgets.QWidget(MainWindow)
        self.centralwidget.setObjectName("centralwidget")
        self.label = QtWidgets.QLabel(self.centralwidget)
        self.label.setGeometry(QtCore.QRect(110,20,61,16))
        self.label.setObjectName("label")
        self.textEdit = QtWidgets.QTextEdit(self.centralwidget)
        self.textEdit.setGeometry(QtCore.QRect(90,60,104,71))
        self.textEdit.setObjectName("textEdit")
        self.pushButton = QtWidgets.QPushButton(self.centralwidget)
        self.pushButton.setGeometry(QtCore.QRect(100,150,75,23))
        self.pushButton.setObjectName("pushButton")
        MainWindow.setCentralWidget(self.centralwidget)
        self.menubar = QtWidgets.QMenuBar(MainWindow)
        self.menubar.setGeometry(QtCore.QRect(0,325,21))
        self.menubar.setObjectName("menubar")
        MainWindow.setMenuBar(self.menubar)
        self.statusbar = QtWidgets.QStatusBar(MainWindow)
        self.statusbar.setObjectName("statusbar")
        MainWindow.setStatusBar(self.statusbar)

        self.retranslateUi(MainWindow)
        QtCore.QMetaObject.connectSlotsByName(MainWindow)

    def retranslateUi(self,MainWindow):
        _translate = QtCore.QCoreApplication.translate
        MainWindow.setWindowTitle(_translate("MainWindow","test window"))
        self.label.setText(_translate("MainWindow","pyqt5 tests"))
        self.pushButton.setText(_translate("MainWindow","test button"))


class MainWindowm(QtWidgets.QMainWindow):
    def __init__(self,*args,**kwargs):
        super(MainWindowm,self).__init__(*args,**kwargs)

        self.canvas = FigureCanvasQTAgg(Figure(figsize=(5,4),dpi=100))
        self.setCentralWidget(self.canvas)

        self.axes = self.canvas.figure.subplots()

        n_data = 10
        self.xdata = list(range(n_data))
        self.ydata = [0 for i in range(n_data)]

    def update_plot(self,value):
        self.ydata = self.ydata[1:] + [value]
        self.axes.cla()
        self.axes.plot(self.xdata,self.ydata,"r")
        self.canvas.draw()


class MainWindow(QtWidgets.QMainWindow,Ui_MainWindow):
    def __init__(self,parent=None):
        super().__init__(parent)
        self.setupUi(self)

    def update_text(self,value):
        self.label.setNum(value)
        self.label.adjustSize()


class SerialManager(QtCore.QObject):
    valueChanged = QtCore.pyqtSignal(float)

    def __init__(self,parent=None):
        super().__init__(parent)
        self.serial_port = QtSerialPort.QSerialPort("COM3")
        self.serial_port.setBaudRate(QtSerialPort.QSerialPort.Baud9600)
        self.serial_port.errorOccurred.connect(self.handle_error)
        self.serial_port.readyRead.connect(self.handle_ready_read)
        self.serial_port.open(QtCore.QIODevice.ReadWrite)

    def handle_ready_read(self):
        while self.serial_port.canReadLine():
            codec = QtCore.QTextCodec.codecForName("UTF-8")
            line = codec.toUnicode(self.serial_port.readLine()).strip().strip("\x00")
            try:
                print(line)
                value = float(line)
            except ValueError as e:
                print("error",e)
            else:
                self.valueChanged.emit(value)

    def handle_error(self,error):
        if error == QtSerialPort.QSerialPort.NoError:
            return
        print(error,self.serial_port.errorString())


if __name__ == "__main__":
    app = QtWidgets.QApplication(sys.argv)
    w1 = MainWindow()
    w1.show()

    w = MainWindowm()
    w.show()

    manager = SerialManager()
    manager.valueChanged.connect(w1.update_text)
    manager.valueChanged.connect(w.update_plot)

    sys.exit(app.exec_())
arduinomatplotlibmultithreadingpyqtpython