lcdnumber signal and slot - pyqt4

Question

I have put together (with lots of researching questions from this site, thank you) some code which will, in part, display raspberry pi input pin voltages on qlcdnumber widgets in my qt creator gui. The code runs perfectly, the gui pops up, and the pin voltage prints to the terminal (temporary) and the buttons are functional in the gui, turning other pins high and low. I don't get any errors, but the issue is that the signal won't display on the gui lcd. I have researched all I can to no success and I feel as though I'm guessing at it now. I would appreciate any input and instruction. I've learned a lot but still have far to go so any help would be great. I am using Raspbian and Qt4/Qt Creator 3.2.1
Here is the entire code and once again thank you for any instruction:
import sys
import RPi.GPIO as GPIO
import time
import re
from PyQt4 import QtGui, uic, QtCore
import spidev
GPIO.setmode(GPIO.BCM)
GPIO.setwarnings(False)
o2zero = 26
o2span = 19
cozero = 13
cospan = 6
co2zero = 5
co2span = 21
status = "nil"
o2_channel = 0
o2_temp_channel = 1
spi = spidev.SpiDev()
spi.open(0,0)
class MyWindow(QtGui.QMainWindow):
def __init__(self):
super(MyWindow, self).__init__()
uic.loadUi('mainwindow.ui', self)
self.o2_zero_up.clicked.connect(self.o2zeroup)
self.o2_zero_down.clicked.connect(self.o2zerodown)
self.o2_span_up.clicked.connect(self.o2spanup)
self.o2_span_down.clicked.connect(self.o2spandown)
self.co_zero_up.clicked.connect(self.cozeroup)
self.co_zero_down.clicked.connect(self.cozerodown)
self.co_span_up.clicked.connect(self.cospanup)
self.co_span_down.clicked.connect(self.cospandown)
self.co2_zero_up.clicked.connect(self.co2zeroup)
self.co2_zero_down.clicked.connect( self.co2zerodown)
self.co2_span_up.clicked.connect(self.co2spanup)
self.co2_span_down.clicked.connect(self.co2spandown)
self.close_button.clicked.connect(self.gpiocleanup)
self.thread = O2_Channel()
self.thread.o2_concentration.connect(self.onChangeValue)
self.thread.start()
self.show()
def onChangeValue(self, values):
o2_volts = values
def o2zeroup(self):
GPIO.setup(o2zero, GPIO.OUT)
GPIO.output(o2zero, 1)
def o2zerodown(self):
GPIO.setup(o2zero, GPIO.OUT)
GPIO.output(o2zero, 0)
def o2spanup(self):
GPIO.setup(o2span, GPIO.OUT)
GPIO.output(o2span, 1)
def o2spandown(self):
GPIO.setup(o2span, GPIO.OUT)
GPIO.output(o2span, 0)
def cozeroup(self):
GPIO.setup(cozero, GPIO.OUT)
GPIO.output(cozero, 1)
def cozerodown(self):
GPIO.setup(cozero, GPIO.OUT)
GPIO.output(cozero, 0)
def cospanup(self):
GPIO.setup(cospan, GPIO.OUT)
GPIO.output(cospan, 1)
def cospandown(self):
GPIO.setup(cospan, GPIO.OUT)
GPIO.output(cospan, 0)
def co2zeroup(self):
GPIO.setup(co2zero, GPIO.OUT)
GPIO.output(co2zero, 1)
def co2zerodown(self):
GPIO.setup(co2zero, GPIO.OUT)
GPIO.output(co2zero, 0)
def co2spanup(self):
GPIO.setup(co2span, GPIO.OUT)
GPIO.output(co2span, 1)
def co2spandown(self):
GPIO.setup(co2span, GPIO.OUT)
GPIO.output(co2span, 0)
def gpiocleanup(self):
GPIO.cleanup()
def closeEvent(self, event):
self.thread.stop()
self.thread.quit()
self.thread.wait()
self.thread.deleteLater()
print ("GPIO CleanUP")
GPIO.cleanup()
event.accept()
def ReadChannel(channel):
adc = spi.xfer2([1,(8+channel)<<4,0])
data = ((adc[1]&3) << 8) + adc[2]
return data
def ConvertVolts(data, places):
volts = (data * 3.3) / float(1023)
volts = round(volts,places)
return volts
class O2_Channel(QtCore.QThread):
o2_concentration = QtCore.pyqtSignal(int)
def __init__(self):
QtCore.QThread.__init__(self)
self.mRunning = True
def run(self):
while self.mRunning:
o2_level = ReadChannel(o2_channel)
o2_volts = ConvertVolts(o2_level,2)
print("{}".format(o2_volts))
self.o2_concentration.emit(o2_volts)
delay = .2
time.sleep(delay)
def stop(self):
self.mRunning = False
if __name__ == '__main__':
app = QtGui.QApplication(sys.argv)
window = MyWindow()
sys.exit(app.exec_())

Answer 1

In a different post, eyllanesc set me up with the signal and slot I needed to display the signal to my gui lcd but I didn't understand it well enough to know just what he did. I've spent the last few days reading about this and finally see just what he did. Everything works and works just like I want it to.
For anyone who might have the same confusion I had, here was my main problem:
def onChangeValue(self, values):
o2_volts = values
I am so new at this that I didn't realize I needed to actually put my specified value in place of the word "values" in the above code. A little embarrassing but part of learning I guess. The other problem was here:
o2_concentration = QtCore.pyqtSignal(int)
I didn't realize it but after I fixed the "values", the lcd was working but was reading 0 and I assumed it wasn't working. Using a photocell to get voltage, I was getting .25 when printing to the terminal but 0 to the lcd. Again being new I didn't think about (int) not being correct for what I wanted. Changing it to (float) fixed the problem. Everything works great.
The my script has grown since the original post but if anyone would like to see it I would be happy to post it.
This is a wonderful site. Thank for everything.