Нажимаешь на кнопку виджета QPushButton и пока не отпускаешь ее выполняется действие

Этот прототип вполне подойдет для дальнейшей разработки. Действие написано для кнопки "Вверх". Пора открывать ветку PyQt5 + Arduino + Raspberry Pi

main.py

import sys
from PyQt5.QtWidgets import QApplication, QMainWindow
from PyQt5.uic import loadUi


class New(QMainWindow):
    def __init__(self):
        super(New, self).__init__()

        loadUi("template1.ui", self)
        self.setWindowTitle('New')

        self.action.triggered.connect(self.exit_action)

        # Свойство автоповтора отключено по умолчанию, поэтому включаем его
        self.pushButton.setAutoRepeat(True)
        # Установка интервала 500 миллисекунд
        self.pushButton.setAutoRepeatInterval(500)
        # Вводим нужное число для начала отсчета. Я использовал 0
        self.counter = 0
        # Добавляем действие к кнопке
        self.pushButton.clicked.connect(lambda: self.upClicked())

    def upClicked(self):
        self.label_4.setText(str(self.counter))
        self.counter += 1

    def exit_action(self):
        self.close()


if __name__ == '__main__':
    app = QApplication(sys.argv)
    window = New()
    window.show()
    sys.exit(app.exec_())

template1.ui

<?xml version="1.0" encoding="UTF-8"?>
<ui version="4.0">
 <class>MainWindow</class>
 <widget class="QMainWindow" name="MainWindow">
  <property name="geometry">
   <rect>
    <x>0</x>
    <y>0</y>
    <width>969</width>
    <height>734</height>
   </rect>
  </property>
  <property name="windowTitle">
   <string>Deqart</string>
  </property>
  <widget class="QWidget" name="centralwidget">
   <widget class="QPushButton" name="pushButton">
    <property name="geometry">
     <rect>
      <x>420</x>
      <y>100</y>
      <width>125</width>
      <height>160</height>
     </rect>
    </property>
    <property name="styleSheet">
     <string notr="true">font: 75 72pt &quot;MS Shell Dlg 2&quot;;</string>
    </property>
    <property name="text">
     <string>▲</string>
    </property>
   </widget>
   <widget class="QPushButton" name="pushButton_2">
    <property name="geometry">
     <rect>
      <x>420</x>
      <y>400</y>
      <width>125</width>
      <height>160</height>
     </rect>
    </property>
    <property name="styleSheet">
     <string notr="true">font: 75 72pt &quot;MS Shell Dlg 2&quot;;</string>
    </property>
    <property name="text">
     <string>▼</string>
    </property>
   </widget>
   <widget class="QPushButton" name="pushButton_3">
    <property name="geometry">
     <rect>
      <x>200</x>
      <y>270</y>
      <width>160</width>
      <height>125</height>
     </rect>
    </property>
    <property name="styleSheet">
     <string notr="true">font: 75 72pt &quot;MS Shell Dlg 2&quot;;</string>
    </property>
    <property name="text">
     <string>◀</string>
    </property>
   </widget>
   <widget class="QPushButton" name="pushButton_4">
    <property name="geometry">
     <rect>
      <x>600</x>
      <y>270</y>
      <width>160</width>
      <height>125</height>
     </rect>
    </property>
    <property name="styleSheet">
     <string notr="true">font: 75 72pt &quot;MS Shell Dlg 2&quot;;</string>
    </property>
    <property name="text">
     <string>▶</string>
    </property>
   </widget>
   <widget class="QLabel" name="label">
    <property name="geometry">
     <rect>
      <x>360</x>
      <y>310</y>
      <width>50</width>
      <height>50</height>
     </rect>
    </property>
    <property name="font">
     <font>
      <pointsize>25</pointsize>
     </font>
    </property>
    <property name="text">
     <string>OX</string>
    </property>
   </widget>
   <widget class="QLabel" name="label_2">
    <property name="geometry">
     <rect>
      <x>550</x>
      <y>310</y>
      <width>50</width>
      <height>50</height>
     </rect>
    </property>
    <property name="font">
     <font>
      <pointsize>25</pointsize>
     </font>
    </property>
    <property name="text">
     <string>OX</string>
    </property>
   </widget>
   <widget class="QLabel" name="label_3">
    <property name="geometry">
     <rect>
      <x>460</x>
      <y>350</y>
      <width>50</width>
      <height>50</height>
     </rect>
    </property>
    <property name="font">
     <font>
      <pointsize>25</pointsize>
     </font>
    </property>
    <property name="text">
     <string>OY</string>
    </property>
   </widget>
   <widget class="QLabel" name="label_4">
    <property name="geometry">
     <rect>
      <x>460</x>
      <y>260</y>
      <width>50</width>
      <height>50</height>
     </rect>
    </property>
    <property name="font">
     <font>
      <pointsize>25</pointsize>
     </font>
    </property>
    <property name="text">
     <string>OY</string>
    </property>
   </widget>
  </widget>
  <widget class="QMenuBar" name="menubar">
   <property name="geometry">
    <rect>
     <x>0</x>
     <y>0</y>
     <width>969</width>
     <height>21</height>
    </rect>
   </property>
   <widget class="QMenu" name="menuFile">
    <property name="title">
     <string>Файл</string>
    </property>
    <addaction name="action"/>
   </widget>
   <widget class="QMenu" name="menu">
    <property name="title">
     <string>Настройки</string>
    </property>
    <addaction name="action_2"/>
   </widget>
   <widget class="QMenu" name="menu_2">
    <property name="title">
     <string>Программирование</string>
    </property>
   </widget>
   <widget class="QMenu" name="menu_3">
    <property name="title">
     <string>Помощь</string>
    </property>
   </widget>
   <addaction name="menuFile"/>
   <addaction name="menu"/>
   <addaction name="menu_2"/>
   <addaction name="menu_3"/>
  </widget>
  <widget class="QStatusBar" name="statusbar"/>
  <action name="action">
   <property name="text">
    <string>Выход</string>
   </property>
  </action>
  <action name="action_2">
   <property name="text">
    <string>Настройки</string>
   </property>
  </action>
 </widget>
 <resources/>
 <connections/>
</ui>