psic-o-tronic/i2c_lcd.py at main · rodillo69/psic-o-tronic · GitHub

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# i2c_lcd.py - Driver I2C para LCD con PCF8574
import time
from lcd_api import LcdApi

# PCF8574 pin definitions
MASK_RS = 0x01       # P0
MASK_RW = 0x02       # P1
MASK_E  = 0x04       # P2
SHIFT_BACKLIGHT = 3  # P3
SHIFT_DATA      = 4  # P4-P7

class I2cLcd(LcdApi):
    def __init__(self, i2c, i2c_addr, num_lines, num_columns):
        self.i2c = i2c
        self.i2c_addr = i2c_addr
        self.i2c.writeto(self.i2c_addr, bytes([0]))
        time.sleep_ms(20)

        # Send reset 3 times
        self.hal_write_init_nibble(0x30)
        time.sleep_ms(5)
        self.hal_write_init_nibble(0x30)
        time.sleep_ms(1)
        self.hal_write_init_nibble(0x30)
        time.sleep_ms(1)

        # Put LCD into 4-bit mode
        self.hal_write_init_nibble(0x20)
        time.sleep_ms(1)

        LcdApi.__init__(self, num_lines, num_columns)

        cmd = 0x20
        if num_lines > 1:
            cmd |= 0x08
        self.hal_write_command(cmd)

    def hal_write_init_nibble(self, nibble):
        byte = ((nibble >> 4) & 0x0f) << SHIFT_DATA
        self.i2c.writeto(self.i2c_addr, bytes([byte | MASK_E]))
        self.i2c.writeto(self.i2c_addr, bytes([byte]))

    def hal_backlight_on(self):
        self.i2c.writeto(self.i2c_addr, bytes([1 << SHIFT_BACKLIGHT]))

    def hal_backlight_off(self):
        self.i2c.writeto(self.i2c_addr, bytes([0]))

    def hal_write_command(self, cmd):
        byte = ((self.backlight << SHIFT_BACKLIGHT) |
                (((cmd >> 4) & 0x0f) << SHIFT_DATA))
        self.i2c.writeto(self.i2c_addr, bytes([byte | MASK_E]))
        self.i2c.writeto(self.i2c_addr, bytes([byte]))

        byte = ((self.backlight << SHIFT_BACKLIGHT) |
                ((cmd & 0x0f) << SHIFT_DATA))
        self.i2c.writeto(self.i2c_addr, bytes([byte | MASK_E]))
        self.i2c.writeto(self.i2c_addr, bytes([byte]))
        if cmd <= 3:
            time.sleep_ms(5)

    def hal_write_data(self, data):
        byte = (MASK_RS |
                (self.backlight << SHIFT_BACKLIGHT) |
                (((data >> 4) & 0x0f) << SHIFT_DATA))
        self.i2c.writeto(self.i2c_addr, bytes([byte | MASK_E]))
        self.i2c.writeto(self.i2c_addr, bytes([byte]))

        byte = (MASK_RS |
                (self.backlight << SHIFT_BACKLIGHT) |
                ((data & 0x0f) << SHIFT_DATA))
        self.i2c.writeto(self.i2c_addr, bytes([byte | MASK_E]))
        self.i2c.writeto(self.i2c_addr, bytes([byte]))