Now that's all well and good but as part of an upcoming project I am planning I have bigger needs. First LCD size. I want to run the 20x4 size so I can display outputs on the first 3 lines and then use the fourth line for menu navigation. Second I am going to be using a 4x3 keypad, a "D-Pad" style button setup,a buzzer, and a few status LEDs. All of this is going to require one 16 pin (28dip)digital I/O expansion chip, MCP23017 to drive the display, the d-pad, buzzers and LEDs. Then an 8pin (18dip) MCP23008 chip to handle the 4x3 keypad. On top of that it needs to be almost 70' away.
So I used their good work in the coding department to jump off from. Obviously since the product limits to the use of the 16x2 displays due to physical space the code needed to be optimized to handle differing display sizes. I went a little beyond that and added some support for handling longer text strings that would usually overflow into the buffer, and in the case of the 4 line displays that means any text in the buffer for line one appears on line 3... :(
Running the example code provided below to demonstrate the EoL handling.
Here is the new "message" function from the Adafruit_CharLCDPlate.py script/class. I just checked in to their Github repo. One thing to note is that this in no way changes the functionality for the normal plate. Any existing scripts will function just like before. But with the addition of handling 4 line displays seamlessly and then all of the EoL features can be added be putting a 1 or 2 in the message function call after your test to print. My github fork
def message(self, text, limitMode = 0):
""" Send string to LCD. Newline wraps to next line"""
lines = str(text).split('\n') # Split at newline(s)
for i, line in enumerate(lines): # For each substring...
if i == 1: # If newline(s),
self.write(0xC0) # set DDRAM address to 2nd line
elif i == 2:
self.write(0x94)
elif i >= 3:
self.write(0xD4)
"""Now depending on the limit mode set by the function call this will handle """
lineLength = len(line)
limit = self.numcols
if limitMode <= 0:
self.write(line, True)
elif lineLength >= limit and limitMode == 1:
'''With the limit mode set to 1 the line is truncated
at the number of columns available on the display'''
limitedLine = line[0:self.numcols]
self.write(limitedLine, True)
elif lineLength >= limit and limitMode == 2:
'''With the limit mode set to 2 the line is truncated
at the number of columns minus 3 to add in an elipse'''
limitedLine = line[0:self.numcols-3]+'...'
self.write(limitedLine, True)
elif lineLength >= limit and limitMode >= 3:
'''Future todo, add in proper, "line after line" cariage return'''
else:
self.write(line, True)
I also had to add the "self.numlines = lines" to the begin function so I could use the column count.
def begin(self, cols, lines):
self.currline = 0
self.numlines = lines
self.numcols = cols
self.clear()
I also spent some time making an example script to leverage this new message function as well as some of the other standard built in functions. Here is my example script on github
#!/usr/bin/python
#----------------------------------------------------------------
# Author: Chris Crumpacker
# Date: May 2013
#
# A demo of some of the built in helper functions of
# the Adafruit_CharLCDPlate.py and Using the EoL_HandlingAnd4LineSupport.py
#
# Using Adafruit_CharLCD code with the I2C and MCP230xx code as well
#----------------------------------------------------------------
numcolumns = 20
numrows = 4
from time import sleep
from Adafruit_CharLCDPlate import Adafruit_CharLCDPlate
lcd = Adafruit_CharLCDPlate()
lcd.begin(numcolumns, numrows)
lcd.backlight(lcd.ON)
lcd.message("LCD 20x4\nDemonstration")
sleep(2)
while True:
#Text on each line alone.
lcd.clear()
lcd.setCursor(0,0)
lcd.message("Line 1")
sleep(1)
lcd.clear()
lcd.setCursor(0,1)
lcd.message("Line 2")
sleep(1)
lcd.clear()
lcd.setCursor(0,2)
lcd.message("Line 3")
sleep(1)
lcd.clear()
lcd.setCursor(0,3)
lcd.message("Line 4")
sleep(1)
# Using the "\n" new line marker
lcd.clear()
lcd.setCursor(0,0)
lcd.message("Line 1")
sleep(1)
lcd.clear()
lcd.setCursor(0,0)
lcd.message("Line 1\nLine 2")
sleep(1)
lcd.clear()
lcd.setCursor(0,0)
lcd.message("Line 1\nLine 2\nLine 3")
sleep(1)
lcd.clear()
lcd.setCursor(0,0)
lcd.message("Line 1\nLine 2\nLine 3\nLine 4")
sleep(1)
# Auto line limiting by length as to not overflow the display
# This is line by line and does not to any caraige returns
lcd.clear()
lcd.setCursor(0,0)
lcd.message("This String is 33 Characters long",1)
sleep(2)
lcd.clear()
lcd.setCursor(0,0)
lcd.message("This String has elpise",2)
sleep(2)
#Scroll text to the right
messageToPrint = "Scrolling Right"
i=0
while i<20:
lcd.clear()
lcd.setCursor(0,0)
suffix = " " * i
lcd.message(suffix + messageToPrint,1)
sleep(.25)
i += 1
# Scroll test in from the Left
messageToPrint = "Scrolling Left"
i=20
while i>=0:
lcd.clear()
lcd.setCursor(0,0)
suffix = " " * i
lcd.message(suffix + messageToPrint,1)
sleep(.25)
i -= 1
sleep(2)
# Printing text backwards, NOT right justified
lcd.clear()
lcd.setCursor(0,0)
lcd.message("Right to left:")
lcd.setCursor(10,1)
lcd.rightToLeft()
lcd.message("Testing")
sleep(2)
# Printing normally from the middle of the line
lcd.clear()
lcd.setCursor(0,0)
lcd.message("Left to Right:")
lcd.setCursor(10,1)
lcd.message("Testing")
sleep(2)
# Enabling the cursor and having it blink
lcd.clear()
lcd.setCursor(0,0)
lcd.cursor()
lcd.blink()
lcd.message("Cursor is blinking")
lcd.setCursor(0,1)
sleep(3)
lcd.noCursor()
lcd.noBlink()
# Turning the backlight off and showing a simple count down
lcd.clear()
lcd.setCursor(0,0)
lcd.message("Backlight off in")
lcd.setCursor(0,3)
lcd.message("Back on in 3sec")
lcd.setCursor(17,0) #Reseting the cursor here keeps us from having to clear the screen, this over writes the previous character
lcd.message("3")
sleep(1)
lcd.setCursor(17,0)
lcd.message("2")
sleep(1)
lcd.setCursor(17,0)
lcd.message("1")
sleep(1)
lcd.backlight(lcd.OFF)
lcd.clear()
lcd.setCursor(0,0)
sleep(3)
lcd.backlight(lcd.ON)
lcd.message("Backlight on")
This is great. I don't imagine you have a schematic you'd be willing to share for this?
ReplyDeleteI don't for my breadboard version... I just looked up how to handle the power and backlight dimming for my display on the Google. and for the MCP wiring to the data pin and the buttons i just looked at Adafruits code and schematic and reverse engineered it :) http://www.adafruit.com/products/1110
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