Hi everyone,
I tried to run a lcd-display ST7066 (probably similar to the hd44870) with
the folowing code:
------------------------------------------------------------------------------------
import Adafruit_BBIO.GPIO as GPIO
import time
# Define GPIO to LCD mapping
LCD_RS="P9_15"
LCD_E="P9_16"
LCD_D4="P9_21"
LCD_D5="P9_22"
LCD_D6="P9_23"
LCD_D7="P9_24"
OUT=GPIO.OUT
LOW=GPIO.LOW
HIGH=GPIO.HIGH
# Define some device constants
LCD_WIDTH = 16 # Maximum characters per line
LCD_CHR = True
LCD_CMD = False
LCD_LINE_1 = 0x00 # LCD RAM address for the 1st line
LCD_LINE_2 = 0x28 # LCD RAM address for the 2nd line
# Timing constants
E_PULSE = 0.00005
E_DELAY = 0.00005
def main():
# Main program block
GPIO.setup(LCD_E,OUT) # E
GPIO.setup(LCD_RS,OUT) # RS
GPIO.setup(LCD_D4,OUT) # DB4
GPIO.setup(LCD_D5,OUT) # DB5
GPIO.setup(LCD_D6,OUT) # DB6
GPIO.setup(LCD_D7,OUT) # DB7
# Initialise display
lcd_init()
def lcd_init():
# Initialise display
lcd_byte(0x30,LCD_CMD) # 110011 Initialise
time.sleep(0.01)
lcd_byte(0x30,LCD_CMD) # 110010 Initialise
time.sleep(0.01)
lcd_byte(0x30,LCD_CMD) # 000110 Cursor move direction
time.sleep(0.01)
lcd_byte(0x20,LCD_CMD) # 001100 Display On,Cursor Off, Blink Off
time.sleep(0.01)
#lcd_byte(0x1C,LCD_CMD) # 101000 Data length, number of lines, font size
# time.sleep(0.01)
lcd_byte(0x0C,LCD_CMD)
time.sleep(0.01)
lcd_byte(0x01,LCD_CMD)
time.sleep(0.01)
#lcd_byte(0x06,LCD_CMD) # 000001 Clear display
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
GPIO.output(LCD_D4, False) # High bits
GPIO.output(LCD_D5, False)
GPIO.output(LCD_D6, False)
GPIO.output(LCD_D7, False)
time.sleep(0.001)
lcd_toggle_enable()
if bits&0x10:
GPIO.output(LCD_D4, True)
if bits&0x20:
GPIO.output(LCD_D5, True)
if bits&0x40:
GPIO.output(LCD_D6, True)
if bits&0x80:
GPIO.output(LCD_D7, True)
time.sleep(E_PULSE)
GPIO.output(LCD_E, True)
time.sleep(E_DELAY)
GPIO.output(LCD_E, False)
time.sleep(E_PULSE)
# lcd_toggle_enable()
GPIO.output(LCD_D4, False)
GPIO.output(LCD_D5, False)
GPIO.output(LCD_D6, False)
GPIO.output(LCD_D7, False)
if bits&0x01:
GPIO.output(LCD_D4, True)
if bits&0x02:
GPIO.output(LCD_D5, True)
if bits&0x04:
GPIO.output(LCD_D6, True)
if bits&0x08:
GPIO.output(LCD_D7, True)
lcd_toggle_enable()
def lcd_toggle_enable():
time.sleep(0.005)
GPIO.output(LCD_E, False)
time.sleep(E_PULSE)
GPIO.output(LCD_E, True)
time.sleep(E_DELAY)
GPIO.output(LCD_E, False)
time.sleep(0.005)
def lcd_string(zeile,text):
if zeile == 1:
lcd_byte(LCD_LINE_1, LCD_CMD)
if zeile == 2:
lcd_byte(LCD_LINE_1, LCD_CMD)
message=text.ljust(LCD_WIDTH,'_')
for i in range(LCD_WIDTH):
lcd_byte(ord(message[i]),LCD_CHR)
main()
lcd_string(1,'abc')
------------------------------------------------------------
but there is no correct output on the display:
<https://lh3.googleusercontent.com/-s1iECSBCKx0/V3vEFefR3PI/AAAAAAAAADc/mO5u2GQWb28afhb7jkIDuAE1O-YnrcpJwCLcB/s1600/WP_20160705_15_52_27_Rich.jpg>
I think that there is something wrong with the toggle or the waittime of
the toggle, but I cant find any error.
Can anybody see an error in the sourcecode?
Thanks for your help.
best regards eyk
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