Display real time data with PyQt and Raspberry - python-3.x

Question

I am currently using the Raspberry Pi 3 to collect data from a temperature and humidity sensor (DHT11) and then display it in a QTextEdit using PyQt4.
The problem is that I would like to do this in real time but I cannot update the data automatically into the interface. Does anyone have any idea about how I can do this?
PS: Here is the link to install Adafruit if you are interested.
Have a good day,
import time
import Adafruit_DHT
from PyQt4 import QtCore, QtGui
try:
_fromUtf8 = QtCore.QString.fromUtf8
except AttributeError:
def _fromUtf8(s):
return s
try:
_encoding = QtGui.QApplication.UnicodeUTF8
def _translate(context, text, disambig):
return QtGui.QApplication.translate(context, text, disambig, _encoding)
except AttributeError:
def _translate(context, text, disambig):
return QtGui.QApplication.translate(context, text, disambig)
class Ui_Room1(object):
def AffichT(self):
sensor=11
pin=4
humidity, temperature = Adafruit_DHT.read_retry(sensor, pin)
if temperature is not None:
print('Temp={0:0.1f}* Humidity={1:0.1f}%'.format(temperature, humidity))
return str(temperature)
else:
print('Failed to get reading. Try again!')
sys.exit(1)
def AffichH(self):
sensor=11
pin=4
humidity, temperature = Adafruit_DHT.read_retry(sensor, pin)
if humidity is not None:
return str(humidity)
else:
print('Failed to get reading. Try again!')
sys.exit(1)
def setupUi(self, Room1):
Room1.setObjectName(_fromUtf8("Room1"))
Room1.resize(674, 422)
sizePolicy = QtGui.QSizePolicy(QtGui.QSizePolicy.Fixed, QtGui.QSizePolicy.Fixed)
sizePolicy.setHorizontalStretch(0)
sizePolicy.setVerticalStretch(0)
sizePolicy.setHeightForWidth(Room1.sizePolicy().hasHeightForWidth())
Room1.setSizePolicy(sizePolicy)
Room1.setMouseTracking(False)
Room1.setStyleSheet(_fromUtf8("image: url(:/gradient1/Images/gradient1.png);\n"
"\n"
""))
self.centralwidget = QtGui.QWidget(Room1)
sizePolicy = QtGui.QSizePolicy(QtGui.QSizePolicy.Fixed, QtGui.QSizePolicy.Fixed)
sizePolicy.setHorizontalStretch(0)
sizePolicy.setVerticalStretch(0)
sizePolicy.setHeightForWidth(self.centralwidget.sizePolicy().hasHeightForWidth())
self.centralwidget.setSizePolicy(sizePolicy)
self.centralwidget.setObjectName(_fromUtf8("centralwidget"))
self.graphicsView = QtGui.QGraphicsView(self.centralwidget)
self.graphicsView.setGeometry(QtCore.QRect(610, 30, 41, 41))
self.graphicsView.setStyleSheet(_fromUtf8("background-color: transparent;\n"
"background-image: url(:/gradient1/Images/logout.png);\n"
"background-repeat: no;"))
self.graphicsView.setFrameShape(QtGui.QFrame.NoFrame)
self.graphicsView.setObjectName(_fromUtf8("graphicsView"))
self.label = QtGui.QLabel(self.centralwidget)
self.label.setGeometry(QtCore.QRect(270, 50, 131, 31))
sizePolicy = QtGui.QSizePolicy(QtGui.QSizePolicy.Fixed, QtGui.QSizePolicy.Fixed)
sizePolicy.setHorizontalStretch(0)
sizePolicy.setVerticalStretch(0)
sizePolicy.setHeightForWidth(self.label.sizePolicy().hasHeightForWidth())
self.label.setSizePolicy(sizePolicy)
font = QtGui.QFont()
font.setPointSize(18)
font.setBold(True)
font.setWeight(75)
self.label.setFont(font)
self.label.setStyleSheet(_fromUtf8("image : none;\n"
"color: #fff;\n"
"background-color: transparent;"))
self.label.setObjectName(_fromUtf8("label"))
self.label_2 = QtGui.QLabel(self.centralwidget)
self.label_2.setGeometry(QtCore.QRect(140, 170, 101, 61))
self.label_2.setStyleSheet(_fromUtf8("image: none;\n"
"color: #fff;\n"
"background-color: #347;"))
self.label_2.setObjectName(_fromUtf8("label_2"))
self.label_3 = QtGui.QLabel(self.centralwidget)
self.label_3.setGeometry(QtCore.QRect(140, 260, 101, 61))
self.label_3.setStyleSheet(_fromUtf8("image: none;\n"
"color: #fff;\n"
"background-color: #347;"))
self.label_3.setObjectName(_fromUtf8("label_3"))
self.label_4 = QtGui.QLabel(self.centralwidget)
self.label_4.setGeometry(QtCore.QRect(300, 170, 101, 61))
self.label_4.setStyleSheet(_fromUtf8("image: none;\n"
"color: #fff;\n"
"background-color: #347;"))
temp = self.AffichT()
self.label_4.setText(_fromUtf8(temp+"°"))
self.label_4.setObjectName(_fromUtf8("label_4"))
self.label_5 = QtGui.QLabel(self.centralwidget)
self.label_5.setGeometry(QtCore.QRect(300, 260, 101, 61))
self.label_5.setStyleSheet(_fromUtf8("image: none;\n"
"color: #fff;\n"
"background-color: #347;"))
hum = self.AffichH()
self.label_5.setText(_fromUtf8(hum)+"%")
self.label_5.setObjectName(_fromUtf8("label_5"))
Room1.setCentralWidget(self.centralwidget)
self.retranslateUi(Room1)
QtCore.QMetaObject.connectSlotsByName(Room1)
def retranslateUi(self, Room1):
Room1.setWindowTitle(_translate("Room1", "Parents Room", None))
self.label.setText(_translate("Room1", "Welcome !", None))
self.label_2.setText(_translate("Room1", "Température:", None))
self.label_3.setText(_translate("Room1", "Humidité:", None))
if __name__ == "__main__":
import sys
app = QtGui.QApplication(sys.argv)
Room1 = QtGui.QMainWindow()
ui = Ui_Room1()
ui.setupUi(Room1)
Room1.show()
sys.exit(app.exec_())`

Answer 1

The following must be taken into account:
Reading a temperature sensor takes time, in the case of DHT it consumes 2 seconds, this is not a general disadvantage since the ambient temperature does not vary rapidly.
As the reading task is very time consuming, it should not be executed in the main thread but in a secondary one and send the information through signals.
import time
import threading
import Adafruit_DHT
from PyQt4 import QtCore, QtGui
try:
_fromUtf8 = QtCore.QString.fromUtf8
except AttributeError:
def _fromUtf8(s):
return s
try:
_encoding = QtGui.QApplication.UnicodeUTF8
def _translate(context, text, disambig):
return QtGui.QApplication.translate(context, text, disambig, _encoding)
except AttributeError:
def _translate(context, text, disambig):
return QtGui.QApplication.translate(context, text, disambig)
class Ui_Room1(object):
def setupUi(self, Room1):
Room1.setObjectName(_fromUtf8("Room1"))
Room1.resize(674, 422)
sizePolicy = QtGui.QSizePolicy(QtGui.QSizePolicy.Fixed, QtGui.QSizePolicy.Fixed)
sizePolicy.setHorizontalStretch(0)
sizePolicy.setVerticalStretch(0)
sizePolicy.setHeightForWidth(Room1.sizePolicy().hasHeightForWidth())
Room1.setSizePolicy(sizePolicy)
Room1.setMouseTracking(False)
Room1.setStyleSheet(
_fromUtf8("image: url(:/gradient1/Images/gradient1.png);\n" "\n" "")
)
self.centralwidget = QtGui.QWidget(Room1)
sizePolicy = QtGui.QSizePolicy(QtGui.QSizePolicy.Fixed, QtGui.QSizePolicy.Fixed)
sizePolicy.setHorizontalStretch(0)
sizePolicy.setVerticalStretch(0)
sizePolicy.setHeightForWidth(
self.centralwidget.sizePolicy().hasHeightForWidth()
)
self.centralwidget.setSizePolicy(sizePolicy)
self.centralwidget.setObjectName(_fromUtf8("centralwidget"))
self.graphicsView = QtGui.QGraphicsView(self.centralwidget)
self.graphicsView.setGeometry(QtCore.QRect(610, 30, 41, 41))
self.graphicsView.setStyleSheet(
_fromUtf8(
"background-color: transparent;\n"
"background-image: url(:/gradient1/Images/logout.png);\n"
"background-repeat: no;"
)
)
self.graphicsView.setFrameShape(QtGui.QFrame.NoFrame)
self.graphicsView.setObjectName(_fromUtf8("graphicsView"))
self.label = QtGui.QLabel(self.centralwidget)
self.label.setGeometry(QtCore.QRect(270, 50, 131, 31))
sizePolicy = QtGui.QSizePolicy(QtGui.QSizePolicy.Fixed, QtGui.QSizePolicy.Fixed)
sizePolicy.setHorizontalStretch(0)
sizePolicy.setVerticalStretch(0)
sizePolicy.setHeightForWidth(self.label.sizePolicy().hasHeightForWidth())
self.label.setSizePolicy(sizePolicy)
font = QtGui.QFont()
font.setPointSize(18)
font.setBold(True)
font.setWeight(75)
self.label.setFont(font)
self.label.setStyleSheet(
_fromUtf8(
"image : none;\n" "color: #fff;\n" "background-color: transparent;"
)
)
self.label.setObjectName(_fromUtf8("label"))
self.label_2 = QtGui.QLabel(self.centralwidget)
self.label_2.setGeometry(QtCore.QRect(140, 170, 101, 61))
self.label_2.setStyleSheet(
_fromUtf8("image: none;\n" "color: #fff;\n" "background-color: #347;")
)
self.label_2.setObjectName(_fromUtf8("label_2"))
self.label_3 = QtGui.QLabel(self.centralwidget)
self.label_3.setGeometry(QtCore.QRect(140, 260, 101, 61))
self.label_3.setStyleSheet(
_fromUtf8("image: none;\n" "color: #fff;\n" "background-color: #347;")
)
self.label_3.setObjectName(_fromUtf8("label_3"))
self.label_4 = QtGui.QLabel(self.centralwidget)
self.label_4.setGeometry(QtCore.QRect(300, 170, 101, 61))
self.label_4.setStyleSheet(
_fromUtf8("image: none;\n" "color: #fff;\n" "background-color: #347;")
)
self.label_4.setObjectName(_fromUtf8("label_4"))
self.label_5 = QtGui.QLabel(self.centralwidget)
self.label_5.setGeometry(QtCore.QRect(300, 260, 101, 61))
self.label_5.setStyleSheet(
_fromUtf8("image: none;\n" "color: #fff;\n" "background-color: #347;")
)
self.label_5.setObjectName(_fromUtf8("label_5"))
Room1.setCentralWidget(self.centralwidget)
self.retranslateUi(Room1)
QtCore.QMetaObject.connectSlotsByName(Room1)
def retranslateUi(self, Room1):
Room1.setWindowTitle(_translate("Room1", "Parents Room", None))
self.label.setText(_translate("Room1", "Welcome !", None))
self.label_2.setText(_translate("Room1", "Température:", None))
self.label_3.setText(_translate("Room1", "Humidité:", None))
class Adafruit_DHT_Worker(QtCore.QObject):
valueChanged = QtCore.pyqtSignal(float, float)
def start(self):
threading.Thread(target=self._read, daemon=True).start()
def _read(self):
sensor=11
pin=4
humidity, temperature = Adafruit_DHT.read_retry(sensor, pin)
if humidity is not None and temperature is not None:
self.valueChanged.emit(temperature, humidity)
class Room1(QtGui.QMainWindow, Ui_Room1):
def __init__(self, parent=None):
super().__init__(parent)
self.setupUi(self)
self.dht_worker = Adafruit_DHT_Worker()
self.dht_worker.valueChanged.connect(self.on_value_changed)
self.dht_worker.start()
#QtCore.pyqtSlot(float, float)
def on_value_changed(self, humidity, temperature):
self.label_4.setNum(temperature)
self.label_5.setNum(humidity)
if __name__ == "__main__":
import sys
app = QtGui.QApplication(sys.argv)
w = Room1()
w.show()
sys.exit(app.exec_())