My setup is: Arduino with 433 cheap transmitter module, photodiode and a laser and 433 receiver connected to Rpi, button.

I've used rpi-rf lib to receive codes. I'm trying to make stopwatch that when i push BTN on Rpi it starts counting and when laser beam is cut, it sends signal to stop the stopwatch. I have no idea how to send signal from receive script to my stopwatch. Later i will post code for stopwatch


# importing libraries 

from PyQt5.QtWidgets import * 
from PyQt5 import QtCore, QtGui 
from PyQt5.QtGui import * 
from PyQt5.QtCore import * 
import sys 

class Window(QMainWindow): 

    def __init__(self): 

       # setting title 
        self.setWindowTitle("Python Stop watch") 

       # setting geometry 
        self.setGeometry(100, 100, 400, 500) 

       # calling method 

       # showing all the widgets 

    # method for widgets 
    def UiComponents(self): 

        # counter 
        self.count = 0

        # creating flag 
        self.flag = False

        # creating a label to show the time 
        self.label = QLabel(self) 

        # setting geometry of label 
        self.label.setGeometry(75, 100, 250, 70) 

        # adding border to the label 
        self.label.setStyleSheet("border : 4px solid black;") 

        # setting text to the label 

        # setting font to the label 
        self.label.setFont(QFont('Arial', 25)) 

        # setting alignment to the text of label 

        # creating start button 
        start = QPushButton("Start", self) 

        # setting geometry to the button 
        start.setGeometry(125, 250, 150, 40) 

        # add action to the method 

        # creating pause button 
        pause = QPushButton("Pause", self) 

        # setting geometry to the button 
        pause.setGeometry(125, 300, 150, 40) 

        # add action to the method 

        # creating reset button 
        re_set = QPushButton("Re-set", self) 

        # setting geometry to the button 
        re_set.setGeometry(125, 350, 150, 40) 

        # add action to the method 

        # creating a timer object 
        timer = QTimer(self) 

        # adding action to timer 

        # update the timer every tenth second 

    # method called by timer 
    def showTime(self): 

        # checking if flag is true 
        if self.flag: 

            # incrementing the counter 
            self.count+= 1

        # getting text from count 
        text = str(self.count / 10) 

        # showing text 

    def Start(self): 

        # making flag to true 
        self.flag = True

    def Pause(self): 

       # making flag to False 
        self.flag = False

    def Re_set(self): 

        # making flag to false 
        self.flag = False

        # reseeting the count 
        self.count = 0

        # setting text to label 


# create pyqt5 app 
App = QApplication(sys.argv) 
# create the instance of our Window 
window = Window() 
# start the app 

1 Answer 1


You can think of the radio modules as a signal converter: the sender modulates a 433MHz wave according to the input signal A (amplitude shift keying). The receiver demodulates the signal and provides the signal A at the output.

You can e.g. use UART to handle the actual communication:

  • connect the arduino's Tx-Signal to the senders input
  • connect the receivers output to Rx of the Raspberry Pi
  • perform communication with Serial.print() (arduino) and pyserial (Pi), just like you would implement an ordinary serial communication. The radio part is completely irrelevant for you.
  • Thing is that Arduino will be 100 meters away. So i really need radio communication, it's crutial. I managed to get radio transmission working but I don't know how to make receiver script to stop my stopwatch when specific message is sent Jun 17, 2021 at 19:59
  • From your point of view, things work exactly the same with radio like they would with a wired connection. You can use the serial functions, because you can feed the radio modules with whatever signal you like (e.g. uart).
    – Sim Son
    Jun 18, 2021 at 13:13

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