How to do it...

1. Create the following script, called lcd_i2c.py:

#!/usr/bin/python3 
#lcd_i2c.py 
import wiringpi2 
import time 
import datetime 
import data_local as dataDevice 
 
AF_BASE=100 
AF_E=AF_BASE+13;     AF_RW=AF_BASE+14;   AF_RS=AF_BASE+15 
AF_DB4=AF_BASE+12;   AF_DB5=AF_BASE+11;  AF_DB6=AF_BASE+10 
AF_DB7=AF_BASE+9 
 
AF_SELECT=AF_BASE+0; AF_RIGHT=AF_BASE+1; AF_DOWN=AF_BASE+2 
AF_UP=AF_BASE+3;     AF_LEFT=AF_BASE+4;  AF_BACK=AF_BASE+5 
 
AF_GREEN=AF_BASE+6;  AF_BLUE=AF_BASE+7;  AF_RED=AF_BASE+8 
BNK=" "*16 #16 spaces 
 
def gpiosetup(): 
  global lcd 
  wiringpi2.wiringPiSetup() 
  wiringpi2.mcp23017Setup(AF_BASE,0x20) 
  wiringpi2.pinMode(AF_RIGHT,0) 
  wiringpi2.pinMode(AF_LEFT,0) 
  wiringpi2.pinMode(AF_SELECT,0) 
  wiringpi2.pinMode(AF_RW,1) 
  wiringpi2.digitalWrite(AF_RW,0) 
  lcd=wiringpi2.lcdInit(2,16,4,AF_RS,AF_E, 
                        AF_DB4,AF_DB5,AF_DB6,AF_DB7,0,0,0,0) 
 
def printLCD(line0="",line1=""): 
  wiringpi2.lcdPosition(lcd,0,0) 
  wiringpi2.lcdPrintf(lcd,line0+BNK) 
  wiringpi2.lcdPosition(lcd,0,1) 
  wiringpi2.lcdPrintf(lcd,line1+BNK) 
 
def checkBtn(idx,size): 
  global run 
  if wiringpi2.digitalRead(AF_LEFT): 
    idx-=1 
    printLCD() 
  elif wiringpi2.digitalRead(AF_RIGHT): 
    idx+=1 
    printLCD() 
  if wiringpi2.digitalRead(AF_SELECT): 
    printLCD("Exit Display") 
    run=False 
  return idx%size 
 
def main(): 
  global run 
  gpiosetup() 
  myData = dataDevice.device() 
  myDataNames = myData.getName() 
  run=True 
  index=0 
  while(run): 
    data = myData.getNew() 
    printLCD(myDataNames[index],str(data[index])) 
    time.sleep(0.2) 
    index = checkBtn(index,len(myDataNames)) 
 
main() 
#End 

2. With the LCD module connected, run the script as follows:

sudo python3 lcd_i2c.py  

Select the data channel you want to display using the left and right buttons and press the SELECT button to exit.