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node-red-nodes/hardware/PiLcd/nrlcd.py

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#!/usr/bin/python
#
# HD44780 LCD Test Script for
# Raspberry Pi
#
# Original Author : Matt Hawkins
# Site : http://www.raspberrypi-spy.co.uk
# Modified to use PINS not BCM : Dave Conway-Jones
#import
import RPi.GPIO as GPIO
import time
import sys
import os
import select
try:
raw_input # Python 2
except NameError:
raw_input = input # Python 3
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# Turn off warnings if you run it a second time...
GPIO.setwarnings(False)
# Define initial Pins to LCD mapping
LCD_RS = 26
LCD_E = 24
LCD_D4 = 22
LCD_D5 = 18
LCD_D6 = 16
LCD_D7 = 12
# Define some device constants
LCD_WIDTH = 20 # Maximum characters per line
LCD_CHR = True
LCD_CMD = False
LCD_LINE_1 = 0x80 # LCD RAM address for the 1st line
LCD_LINE_2 = 0xC0 # LCD RAM address for the 2nd line
LCD_LINE_3 = 0x94 # LCD RAM address for the 3rd line
LCD_LINE_4 = 0xD4 # LCD RAM address for the 4th line
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# Timing constants
E_PULSE = 0.0005
E_DELAY = 0.0005
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def lcd_init():
# Initialise display
lcd_byte(0x33,LCD_CMD)
lcd_byte(0x32,LCD_CMD)
lcd_byte(0x0C,LCD_CMD)
lcd_byte(0x06,LCD_CMD)
lcd_byte(0x28,LCD_CMD)
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lcd_byte(0x01,LCD_CMD)
time.sleep(E_DELAY)
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def lcd_string(message):
# Send string to display
message = message.ljust(LCD_WIDTH," ")
for i in range(LCD_WIDTH):
lcd_byte(ord(message[i]),LCD_CHR)
def lcd_byte(bits, mode):
# Send byte to data pins
# bits = data
# mode = True for character
# False for command
GPIO.output(LCD_RS, mode) # RS
# High bits
GPIO.output(LCD_D4, False)
GPIO.output(LCD_D5, False)
GPIO.output(LCD_D6, False)
GPIO.output(LCD_D7, False)
if bits&0x10==0x10:
GPIO.output(LCD_D4, True)
if bits&0x20==0x20:
GPIO.output(LCD_D5, True)
if bits&0x40==0x40:
GPIO.output(LCD_D6, True)
if bits&0x80==0x80:
GPIO.output(LCD_D7, True)
# Toggle 'Enable' pin
time.sleep(E_DELAY)
GPIO.output(LCD_E, True)
time.sleep(E_PULSE)
GPIO.output(LCD_E, False)
time.sleep(E_DELAY)
# Low bits
GPIO.output(LCD_D4, False)
GPIO.output(LCD_D5, False)
GPIO.output(LCD_D6, False)
GPIO.output(LCD_D7, False)
if bits&0x01==0x01:
GPIO.output(LCD_D4, True)
if bits&0x02==0x02:
GPIO.output(LCD_D5, True)
if bits&0x04==0x04:
GPIO.output(LCD_D6, True)
if bits&0x08==0x08:
GPIO.output(LCD_D7, True)
# Toggle 'Enable' pin
time.sleep(E_DELAY)
GPIO.output(LCD_E, True)
time.sleep(E_PULSE)
GPIO.output(LCD_E, False)
time.sleep(E_DELAY)
# Main program loop
if len(sys.argv) > 1:
pins = sys.argv[1].lower().split(',')
if len(pins) != 6:
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print("Bad number of pins supplied")
print(" "+pins)
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sys.exit(0)
LCD_RS = int(pins[0])
LCD_E = int(pins[1])
LCD_D4 = int(pins[2])
LCD_D5 = int(pins[3])
LCD_D6 = int(pins[4])
LCD_D7 = int(pins[5])
GPIO.setwarnings(False)
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GPIO.setmode(GPIO.BOARD) # Use GPIO BOARD numbers
GPIO.setup(LCD_RS, GPIO.OUT) # RS
GPIO.setup(LCD_E, GPIO.OUT) # E
GPIO.setup(LCD_D4, GPIO.OUT) # DB4
GPIO.setup(LCD_D5, GPIO.OUT) # DB5
GPIO.setup(LCD_D6, GPIO.OUT) # DB6
GPIO.setup(LCD_D7, GPIO.OUT) # DB7
# Initialise display
lcd_init()
# Send some test
lcd_byte(LCD_LINE_1, LCD_CMD)
lcd_string("Node-RED")
lcd_byte(LCD_LINE_2, LCD_CMD)
lcd_string("LCD online")
time.sleep(2) # 2 second delay
lcd_byte(0x01,LCD_CMD)
# Flush stdin so we start clean
while len(select.select([sys.stdin.fileno()], [], [], 0.0)[0])>0:
os.read(sys.stdin.fileno(), 4096)
while True:
try:
data = raw_input()
data = data.rstrip("\r\n\t")
if data == "c:lose": # cleanup and exit
GPIO.cleanup(LCD_RS)
GPIO.cleanup(LCD_E)
GPIO.cleanup(LCD_D4)
GPIO.cleanup(LCD_D5)
GPIO.cleanup(LCD_D6)
GPIO.cleanup(LCD_D7)
sys.exit(0)
elif data == "clr:": # clear the display
lcd_init()
elif data.startswith("1:"):
lcd_byte(LCD_LINE_1, LCD_CMD)
lcd_string(data[2:])
elif data.startswith("2:"):
lcd_byte(LCD_LINE_2, LCD_CMD)
lcd_string(data[2:])
elif data.startswith("3:"):
lcd_byte(LCD_LINE_3, LCD_CMD)
lcd_string(data[2:])
elif data.startswith("4:"):
lcd_byte(LCD_LINE_4, LCD_CMD)
lcd_string(data[2:])
else: # default to line 1
lcd_byte(LCD_LINE_1, LCD_CMD)
lcd_string(data)
except EOFError: # hopefully always caused by us sigint'ing the program
GPIO.cleanup(LCD_RS)
GPIO.cleanup(LCD_E)
GPIO.cleanup(LCD_D4)
GPIO.cleanup(LCD_D5)
GPIO.cleanup(LCD_D6)
GPIO.cleanup(LCD_D7)
sys.exit(0)
else:
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print("Bad params")
print(" sudo nrlcd.py RS,E,D4,D5,D6,D7")
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sys.exit(0)