import sys
import serial
import time
from PyQt5.QtWidgets import QApplication, QWidget, QMainWindow, QTextEdit
from PyQt5.QtWidgets import QLineEdit, QPushButton, QVBoxLayout, QGridLayout
from PyQt5 import QtCore, QtGui
from PyQt5.QtGui import *
from PyQt5.QtWidgets import *
from PyQt5.QtCore import *

class Main(QMainWindow):
    def __init__(self, parent = None):
        QMainWindow.__init__(self, parent)
        self.resize(250, 350)
        self.setWindowTitle('Serial Reader')

        self.ser = serial.Serial(
            port='/dev/ttyUSB0',
            baudrate = 9600,
            parity=serial.PARITY_NONE,
            stopbits=serial.STOPBITS_ONE,
            bytesize=serial.EIGHTBITS,
            timeout=1
        )

        self.button = QPushButton('Send data - ', self)
        self.button.clicked.connect(self.handleBtn)

        self.textEdit = QTextEdit(self)
        self.textEdit.resize(250, 300)

        self.lineEdit = QLineEdit(self)
        self.lineEdit.resize(150, 30)
        self.lineEdit.move(100, 320)
        self.button.move(0, 320)

        self.timer = QTimer()
        self.timer.setInterval(1)
        self.timer.timeout.connect(self.recurring_timer)
        self.timer.start()

    def handleBtn(self):
        data = self.lineEdit.text() + '\n'
        self.ser.write(data.encode())
        content = self.textEdit.toPlainText() + '----------------------------------\n'
        self.textEdit.setText(content)
        print(data.encode())

    def recurring_timer(self):
        if self.ser.inWaiting():
            x=self.ser.readline()
            content = self.textEdit.toPlainText() + x.decode()
            self.textEdit.setText(content)
            self.textEdit.verticalScrollBar().setValue(self.textEdit.verticalScrollBar().maximum());

if __name__ == '__main__':

    app = QApplication(sys.argv)

    window = Main()
    window.show()

    sys.exit(app.exec_())