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Projects/Advanced_RGB_LCD_TempAndHumidity/grovepi_lcd_dht.py

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+# grovepi_lcd_dht.py
+#
+# This is an project for using the Grove RGB_LED Display and the Grove DHT Sensor from the GrovePi starter kit
+# 
+# In this project, the Temperature and humidity from the DHT sensor is printed on the RGB_LCD Display
+'''
+The MIT License (MIT)
+
+GrovePi for the Raspberry Pi: an open source platform for connecting Grove Sensors to the Raspberry Pi.
+Copyright (C) 2017  Dexter Industries
+
+Permission is hereby granted, free of charge, to any person obtaining a copy
+of this software and associated documentation files (the "Software"), to deal
+in the Software without restriction, including without limitation the rights
+to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+copies of the Software, and to permit persons to whom the Software is
+furnished to do so, subject to the following conditions:
+
+The above copyright notice and this permission notice shall be included in
+all copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+THE SOFTWARE.
+'''
+
+import decimal
+from grovepi import *
+from grove_rgb_lcd import *
+
+dht_sensor_port = 7     # Connect the DHt sensor to port 7
+lastTemp = 0.1          # initialize a floating point temp variable
+lastHum = 0.1           # initialize a floating Point humidity variable
+tooLow = 62.0           # Lower limit in fahrenheit
+justRight = 68.0        # Perfect Temp in fahrenheit
+tooHigh = 74.0          # Temp Too high
+
+
+# Function Definitions
+def CtoF( tempc ):
+   "This converts celcius to fahrenheit"
+   tempf = round((tempc * 1.8) + 32, 2);
+   return tempf;
+
+def FtoC( tempf ):
+   "This converts fahrenheit to celcius"
+   tempc = round((tempf - 32) / 1.8, 2)
+   return tempc;
+
+def calcColorAdj(variance):     # Calc the adjustment value of the background color
+    "Because there is 6 degrees mapping to 255 values, 42.5 is the factor for 12 degree spread"
+    factor = 42.5;
+    adj = abs(int(factor * variance));
+    if adj > 255:
+        adj = 255;
+    return adj;
+
+def calcBG(ftemp):
+    "This calculates the color value for the background"
+    variance = ftemp - justRight;   # Calculate the variance
+    adj = calcColorAdj(variance);   # Scale it to 8 bit int
+    bgList = [0,0,0]               # initialize the color array
+    if(variance < 0):
+        bgR = 0;                    # too cold, no red
+        bgB = adj;                  # green and blue slide equally with adj
+        bgG = 255 - adj;
+        
+    elif(variance == 0):             # perfect, all on green
+        bgR = 0;
+        bgB = 0;
+        bgG = 255;
+        
+    elif(variance > 0):             #too hot - no blue
+        bgB = 0;
+        bgR = adj;                  # Red and Green slide equally with Adj
+        bgG = 255 - adj;
+        
+    bgList = [bgR,bgG,bgB]          #build list of color values to return
+    return bgList;
+
+while True:
+
+    try:
+        temp = 0.01
+        hum = 0.01
+        [ temp,hum ] = dht(dht_sensor_port,1)       #Get the temperature and Humidity from the DHT sensor
+                                                    #Change the second parameter to 0 when using DHT (instead of DHT Pro)
+                                                    #You will get very large number values if you don't!
+        if (CtoF(temp) != lastTemp) and (hum != lastHum) and not math.isnan(temp) and not math.isnan(hum):
+                print("lowC : ",FtoC(tooLow),"C\t\t","rightC  : ", FtoC(justRight),"C\t\t","highC : ",FtoC(tooHigh),"C") # comment these three lines
+                print("lowF : ",tooLow,"F\t\tjustRight : ",justRight,"F\t\ttoHigh : ",tooHigh,"F")                       # if no monitor display
+                print("tempC : ", temp, "C\t\ttempF : ",CtoF(temp),"F\t\tHumidity =", hum,"%\r\n")
+                
+                lastHum = hum          # save temp & humidity values so that there is no update to the RGB LCD
+                ftemp = CtoF(temp)     # unless the value changes
+                lastTemp = ftemp       # this reduces the flashing of the display
+                # print "ftemp = ",ftemp,"  temp = ",temp   # this was just for test and debug
+                
+                bgList = calcBG(ftemp)           # Calculate background colors
+                
+                t = str(ftemp)   # "stringify" the display values
+                h = str(hum)
+                # print "(",bgList[0],",",bgList[1],",",bgList[2],")"   # this was to test and debug color value list
+                setRGB(bgList[0],bgList[1],bgList[2])   # parse our list into the color settings
+                setText("Temp:" + t + "F      " + "Humidity :" + h + "%") # update the RGB LCD display
+                
+    except (IOError,TypeError) as e:
+        print("Error" + str(e))
+