I had directly tested your modified code, it was still not working.
However, your modification gives enough clues (using the i2c.writeto_mem function to write the command to the exact register.). I re-modified the driver as below, and it works perfectly. https://github.com/zhoumaomao11/python_ ... CP23008.py
I appreciate all your help!
Code: Select all
"""Implements a HD44780 character LCD connected via MCP23008 backpack on I2C bus of Lopy4 board.
This was tested with: https://www.wemos.cc/product/d1-mini.html"""
from lcd_api import LcdApi
from machine import I2C
from time import sleep_ms
# The PCF8574 has a jumper selectable address: 0x20 - 0x27
DEFAULT_I2C_ADDR = 0x20
# Specifically for HD44780 character LCD mounted with MCP23008 backpack
# MCP23008 Registers
IODIR = 0x00
IPOL = 0x01
GPINTEN = 0x02
DEFVAL = 0x03
INTCON = 0x04
IOCON = 0x05
GPPU = 0x06
INTF = 0x07
INTCAP = 0x08
GPIO = 0x09
OLAT = 0x0A
MASK_RS = 0x02
MASK_E = 0x04
SHIFT_DATA = 3
SHIFT_BACKLIGHT = 7
class I2cLcd(LcdApi):
"""Implements a HD44780 character LCD connected via PCF8574 on I2C."""
def __init__(self, i2c, i2c_addr, num_lines, num_columns):
self.i2c = i2c
self.i2c_addr = i2c_addr
self.i2c.writeto(self.i2c_addr, b'\x00\xff\x00\x00\x00\x00\x00\x00\x00\x00\x00')# modified
self.i2c.writeto_mem(self.i2c_addr, IODIR, bytearray([0x01]))
sleep_ms(20) # Allow LCD time to powerup
# Send reset 3 times
self.hal_write_init_nibble(self.LCD_FUNCTION_RESET)
sleep_ms(5) # need to delay at least 4.1 msec
self.hal_write_init_nibble(self.LCD_FUNCTION_RESET)
sleep_ms(1)
self.hal_write_init_nibble(self.LCD_FUNCTION_RESET)
sleep_ms(1)
# Put LCD into 4 bit mode
self.hal_write_init_nibble(self.LCD_FUNCTION)
sleep_ms(1)
LcdApi.__init__(self, num_lines, num_columns)
cmd = self.LCD_FUNCTION
if num_lines > 1:
cmd |= self.LCD_FUNCTION_2LINES
self.hal_write_command(cmd)
def hal_write_init_nibble(self, nibble):
"""Writes an initialization nibble to the LCD.
This particular function is only used during initialization.
"""
byte = ((nibble >> 4) & 0x0f) << SHIFT_DATA
#self.i2c.writeto(self.i2c_addr, bytearray([byte | MASK_E])) # original
#self.i2c.writeto(self.i2c_addr, bytearray([byte])) # original
self.i2c.writeto_mem(self.i2c_addr, GPIO, bytearray([byte | MASK_E]))
self.i2c.writeto_mem(self.i2c_addr, GPIO, bytearray([byte]))
def hal_backlight_on(self):
"""Allows the hal layer to turn the backlight on."""
#self.i2c.writeto(self.i2c_addr, bytearray([1 << SHIFT_BACKLIGHT])) # original
self.i2c.writeto_mem(self.i2c_addr, GPIO, 1 << SHIFT_BACKLIGHT)
def hal_backlight_off(self):
"""Allows the hal layer to turn the backlight off."""
#self.i2c.writeto(self.i2c_addr, bytearray([0])) # original
self.i2c.writeto_mem(self.i2c_addr, GPIO, 0)
def hal_write_command(self, cmd):
"""Writes a command to the LCD.
Data is latched on the falling edge of E.
"""
byte = ((self.backlight << SHIFT_BACKLIGHT) |
(((cmd >> 4) & 0x0f) << SHIFT_DATA))
#self.i2c.writeto(self.i2c_addr, bytearray([byte | MASK_E])) # original
#self.i2c.writeto(self.i2c_addr, bytearray([byte])) # original
self.i2c.writeto_mem(self.i2c_addr, GPIO, bytearray([byte | MASK_E]))
self.i2c.writeto_mem(self.i2c_addr, GPIO, bytearray([byte]))
byte = ((self.backlight << SHIFT_BACKLIGHT) |
((cmd & 0x0f) << SHIFT_DATA))
#self.i2c.writeto(self.i2c_addr, bytearray([byte | MASK_E])) # original
#self.i2c.writeto(self.i2c_addr, bytearray([byte])) # original
self.i2c.writeto_mem(self.i2c_addr, GPIO, bytearray([byte | MASK_E]))
self.i2c.writeto_mem(self.i2c_addr, GPIO, bytearray([byte]))
if cmd <= 3:
# The home and clear commands require a worst case delay of 4.1 msec
sleep_ms(5)
def hal_write_data(self, data):
"""Write data to the LCD."""
byte = (MASK_RS |
(self.backlight << SHIFT_BACKLIGHT) |
(((data >> 4) & 0x0f) << SHIFT_DATA))
#self.i2c.writeto(self.i2c_addr, bytearray([byte | MASK_E])) # original
#self.i2c.writeto(self.i2c_addr, bytearray([byte])) # original
self.i2c.writeto_mem(self.i2c_addr, GPIO, bytearray([byte | MASK_E]))
self.i2c.writeto_mem(self.i2c_addr, GPIO, bytearray([byte]))
byte = (MASK_RS |
(self.backlight << SHIFT_BACKLIGHT) |
((data & 0x0f) << SHIFT_DATA))
#self.i2c.writeto(self.i2c_addr, bytearray([byte | MASK_E])) # original
#self.i2c.writeto(self.i2c_addr, bytearray([byte])) # original
self.i2c.writeto_mem(self.i2c_addr, GPIO, bytearray([byte | MASK_E]))
self.i2c.writeto_mem(self.i2c_addr, GPIO, bytearray([byte]))