LCD I2C Python - Home of Manuel Magninch

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LCD I2C Python

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LCD Text Displays mit 2 und 4 Zeilen in Python nutzen

Es gibt inzwischen hunderte von überaus kostengünstigen LCD Displays mit dem Kontroller HD44780. Dieser ist inzwischen ein De-facto-Industriestandard geworden. Es gibt 8x1 Zeichen bis 4x20 Zeichen Anzeigen. Das 2x16 Zeichen Display gibts schon für unter 10 Fr. / Euro mit Standard Interface und mit I2C Zusatz-Platine. HD44780 – Wikipedia

Anschluss des LCD Displays mit I2C Schnittstelle an einen Raspberry Pico:

Pico-Pin1 GP0 <-> LCD-SDA (GP0 mit 0/3.3V Logik)
Pico-Pin2 GP1 <-> LCD-SDL (GP1 mit 0/3.3V Logik)
Pico-Pin40 VBUS <-> LCD-VCC (+5V)
Pico-Pin38 GND <-> LCD-GND Original Datenblatt HD44780.

Anbei ein Testprogramm in Python geschrieben für Raspberry Pico und weitere. Das Demo-Script benötigt keine weiteren Scripts die importiert werden müssen (Das Script ist eigenständig). Das Script wurde möglichst einfach und gradlinig programmiert, um die Funktion klar zu zeigen.

from machine import Pin

from machine import I2C

import utime

print("Test-Script for LCD Dispay with HD44780 Controller and I2C Interfache Chip PCF8574")

# Initialize I2C with pins SDA=GP0 (Pico-Pin1), SDL=GP1 (Pico-Pin2) :: LCD VCC=+5V SDA/SDL 3.3V Logic

i2c=machine.I2C(0, sda=machine.Pin(0), scl=machine.Pin(1), freq=100000)

# Scan I2C BUS to Display correct wired I2C devices

devices = i2c.scan()

for d in devices:

print('I2C Device found at Address: ',hex(d))

#For I2C Controller PCF8574 with HD44780 LCD 2x16 or 4x40 Hardware Wiering Parameter

I2C_LCD_Addr = 0x27 # Must bee one of the scanned I2C Adresses!

LCD_RS = 0x01 # am PFC01 needed for Selecting 0=Command 1=DAta

LCD_RW = 0x02 # am PFC02 propably not connect and at the LCD fix to GND

LCD_E = 0x04 # am PFC03 needed to transfer the Data

LCD_LED= 0x08 # am PFC04 propably not connect and at the LCD fix to On

LCD_D4 = 0x10 # am PFC05

LCD_D5 = 0x20 # am PFC06

LCD_D6 = 0x40 # am PFC07

LCD_D7 = 0x80 # am PFC08

# LCD Service Routines

def LCD_WriteCmd4(Zeichen): # Commands in zwei Nibbles übermitteln

i2c.writeto(I2C_LCD_Addr, bytes([(Zeichen & 0x0F0)+LCD_LED] ) ) # 4-Bit-Data=0x?0 + 00-Register

i2c.writeto(I2C_LCD_Addr, bytes([(Zeichen & 0x0F0)+LCD_LED+LCD_E]) ) # 4-Bit-Data=0x?0 + 04-Enable + 00-Register

i2c.writeto(I2C_LCD_Addr, bytes([(Zeichen & 0x0F0)+LCD_LED]) ) # 4-Bit-Data=0x?0 + 00-Register

def LCD_WriteCmd(Zeichen): # Commands in zwei Nibbles übermitteln

i2c.writeto(I2C_LCD_Addr, bytes([(Zeichen & 0x0F0)+LCD_LED] ) ) # 4-Bit-Data=0x?0 + 00-Register

i2c.writeto(I2C_LCD_Addr, bytes([(Zeichen & 0x0F0)+LCD_LED+LCD_E]) ) # 4-Bit-Data=0x20 + 04-Enable + 00-Register

i2c.writeto(I2C_LCD_Addr, bytes([(Zeichen & 0x0F0)+LCD_LED]) ) # 4-Bit-Data=0x20 + 00-Register

Zeichen = Zeichen << 4

i2c.writeto(I2C_LCD_Addr, bytes([(Zeichen & 0x0F0)+LCD_LED]) ) # 4-Bit-Data=0x?0 + 00-Register

i2c.writeto(I2C_LCD_Addr, bytes([(Zeichen & 0x0F0)+LCD_LED+LCD_E]) ) # 4-Bit-Data=0x20 + 04-Enable + 00-Register

i2c.writeto(I2C_LCD_Addr, bytes([(Zeichen & 0x0F0)+LCD_LED])) # 4-Bit-Data=0x?0 + 08-Licht

def LCD_WriteChar(Zeichen): # Zeichen in zwei Nibbles übermitteln

i2c.writeto(I2C_LCD_Addr, bytes([(Zeichen & 0x0F0)+LCD_LED+LCD_RS])) # 4-Bit-Data=0x?0 + 08-Licht + 01-Register

i2c.writeto(I2C_LCD_Addr, bytes([(Zeichen & 0x0F0)+LCD_LED+LCD_RS+LCD_E])) # Data=0x?0 + 04-Enable, 01-Register

i2c.writeto(I2C_LCD_Addr, bytes([(Zeichen & 0x0F0)+LCD_LED+LCD_RS])) # 4-Bit-Data=0x?0 + 08-Licht + 01-Register

Zeichen = Zeichen << 4

i2c.writeto(I2C_LCD_Addr, bytes([(Zeichen & 0x0F0)+LCD_LED+LCD_RS])) # 4-Bit-Data=0x?0 + 08-Licht + 01-Register

i2c.writeto(I2C_LCD_Addr, bytes([(Zeichen & 0x0F0)+LCD_LED+LCD_RS+LCD_E])) # Data=0x?0 + 04-Enable, 01-Register

i2c.writeto(I2C_LCD_Addr, bytes([(Zeichen & 0x0F0)+LCD_LED+LCD_RS])) # 4-Bit-Data=0x?0 + 08-Licht + 01-Register

def LCD_Init():

try: # Catch I2C Communication Error

LCD_WriteCmd4(0x30) # 0011 D7-D4 HiNibble = SoftReset Sequenz1

except: # Set HD44780 Controller with 4-Bit and Init for use

print("I2C Communiation to " + hex(I2C_LCD_Addr) + "h failed - please Check as the I2C Address ist valid")

import sys

sys.exit("I2C Communiation Error") # TERMINATE SCRIPT ON ERROR

utime.sleep_ms(5) # Delay 5ms SoftReset Sequenz1 zu SoftReset Sequenz2

LCD_WriteCmd4(0x30) # 0011 D7-D4 HiNibble = SoftReset Sequenz2

utime.sleep_ms(1) # Delay 1ms SoftReset Sequenz2 zu SoftReset Sequenz3

LCD_WriteCmd4(0x30) # 0011 D7-D4 HiNibble = SoftReset Sequenz3

utime.sleep_ms(1) # Delay 1ms SoftReset Sequenz3 zu 4-Bit Init

LCD_WriteCmd4(0x20) # 0010 D7-D4 HiNibble = 4-Bit Mode Init

LCD_WriteCmd(0x28) # 0010 1000 - 4Bit Mode Activate

LCD_WriteCmd(0x0C) # 0000 1100 - Display ON, Cursor Off, Cursor Blinking Off

LCD_WriteCmd(0x06) # 0000 0110 - Entry Mode, Increment cursor position, No display shift

LCD_WriteCmd(0x01) # 0000 0001 - Clear Display and Set Cursor to pos 0

utime.sleep_ms(5) # Controller needs Time to Clear the Display

LCD_WriteCmd(0x02) # 0000 0010 - Set Cursor to home Pos=0 needs 1.52mS

utime.sleep_ms(2) # Controller needs Time to Set Cursor Home, needs 1.52mS

def LCD_GotoXY(Position): # Somme HD44780 2end row starts at pos 41 others at 64

if Position > 0x7F : Position=0x7F

LCD_WriteCmd(0x80+Position) # 1000 0000 - 0x80 + Position

def LCD_CLR(): # LCD Löschen via Kommando HD44780

LCD_WriteCmd(0x01) # 0000 0001 - Display Löschen und Cursor auf 0

utime.sleep_ms(2) # Controller needs Time to Clear the Display, needs 1.52mS

def LCD_Print(LCDText): # Print String at the actal position

for Zeichen in LCDText: # Send Character by character

LCD_WriteChar(ord(Zeichen))

# *** MAIN PROGRAMM ***

LCD_Init() # Set HD44780 Controller with 4-Bit and Init for use

LCD_CLR() # Not Needed here, is with Init allready done

LCD_Print("** Hello World **")

LCD_GotoXY(64) # Pos 64 (or 40) is second row

LCD_Print("LCD-I2C HD44780 Cont")

LCD_GotoXY(20) # Pos 20 is 3th row on 4x20 Display

import sys # Onely needed for the Output of the Python Version

LCD_Print("Python: " + sys.version[0:6])

LCD_GotoXY(84) # Pos 84 (64+20) is 4th row on 4x20 Display

try: # Protect Script if it runs not on a Raspberry Pico Board

from machine import ADC

machine.Pin(29, machine.Pin.IN) # the ADC i.o. Pin needs to set as imput, for correct value turn off pull up/down

LCD_Print("V-SYS: " + str(machine.ADC(3).read_u16()*3.23*3/65535)[0:6] + " Volt")

except:

LCD_Print("V-SYS: No ADC present")

# *** ENDE OF MAIN PROGRAMM ***