from machine import Pin, I2C, ADC  
from time import sleep 
from esp32_i2c_lcd import I2cLcd

lcdI2C=I2C(scl=Pin(22),sda=Pin(21),freq=100000)
lcd=I2cLcd(lcdI2C,39,2,16)

led1=Pin(33,Pin.OUT)
varR=ADC(Pin(33))
varR.atten(ADC.ATTN_11DB)

while True:
  varR_value = varR.read()
  brightness = varR_value 
  led1.value(brightness)
  sleep(0.2)
  lcd.clear()
  lcd.move_to(0,0)
  lcd.putstr('ADC = '+str(varR.read()))
  lcd.move_to(0,1)
  lcd.putstr('Voltage = '+"{:.1f}".format(varR.read()*3.3/4095)+' V')
  sleep(1)
  print('ADC = ',varR.read())
  print('Voltage = ',varR.read()*3.3/4095, 'V')
  sleep(1)

  

main.py

diagram.json

"""Implements a character based lcd connected via PCF8574 on I2C."""

from lcd_api import LcdApi
from machine import I2C
from time import sleep_ms

DEFAULT_I2C_ADDR = 0x27

# Defines shifts or masks for the various LCD line attached to the PCF8574

MASK_RS = 0x01
MASK_RW = 0x02
MASK_E = 0x04
SHIFT_BACKLIGHT = 3
SHIFT_DATA = 4


class I2cLcd(LcdApi):
    """Implements a character based 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, bytearray([0]))
        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 intiialization.
        """
        byte = ((nibble >> 4) & 0x0f) << SHIFT_DATA
        self.i2c.writeto(self.i2c_addr, bytearray([byte | MASK_E]))
        self.i2c.writeto(self.i2c_addr, 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]))

    def hal_backlight_off(self):
        """Allows the hal layer to turn the backlight off."""
        self.i2c.writeto(self.i2c_addr, bytearray([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]))
        self.i2c.writeto(self.i2c_addr, bytearray([byte]))
        byte = ((self.backlight << SHIFT_BACKLIGHT) | ((cmd & 0x0f) << SHIFT_DATA))
        self.i2c.writeto(self.i2c_addr, bytearray([byte | MASK_E]))
        self.i2c.writeto(self.i2c_addr, 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]))
        self.i2c.writeto(self.i2c_addr, bytearray([byte]))
        byte = (MASK_RS | (self.backlight << SHIFT_BACKLIGHT) | ((data & 0x0f) << SHIFT_DATA))
        self.i2c.writeto(self.i2c_addr, bytearray([byte | MASK_E]))
        self.i2c.writeto(self.i2c_addr, bytearray([byte]))


esp32_i2c_lcd.py

"""Provides an API for talking to HD44780 style character LCDs."""


class LcdApi:
    """Implements the API for talking with n LCD. This class only knows what
    commands to send to the LCD, and not how t get them to the LCD.

    It is expected that a derived class will implement the hal_xxx functions.
    """

    # The following constant names were lifted from the avrlib lcd.h
    # header file, however, I changed the definitions from bit numbers
    # to bit masks.
    #
    # HD44780 LCD controller command set

    LCD_CLR = 0x01              # DB0: clear display
    LCD_HOME = 0x02             # DB1: return to home position

    LCD_ENTRY_MODE = 0x04       # DB2: set entry mode
    LCD_ENTRY_INC = 0x02        # --DB1: increment
    LCD_ENTRY_SHIFT = 0x01      # --DB0: shift

    LCD_ON_CTRL = 0x08          # DB3: turn lcd/cursor on
    LCD_ON_DISPLAY = 0x04       # --DB2: turn display on
    LCD_ON_CURSOR = 0x02        # --DB1: turn cursor on
    LCD_ON_BLINK = 0x01         # --DB0: blinking cursor

    LCD_MOVE = 0x10             # DB4: move cursor/display
    LCD_MOVE_DISP = 0x08        # --DB3: move display (0-> move cursor)
    LCD_MOVE_RIGHT = 0x04       # --DB2: move right (0-> left)

    LCD_FUNCTION = 0x20         # DB5: function set
    LCD_FUNCTION_8BIT = 0x10    # --DB4: set 8BIT mode (0->4BIT mode)
    LCD_FUNCTION_2LINES = 0x08  # --DB3: two lines (0->one line)
    LCD_FUNCTION_10DOTS = 0x04  # --DB2: 5x10 font (0->5x7 font)
    LCD_FUNCTION_RESET = 0x30   # See "Initializing by Instruction" section

    LCD_CGRAM = 0x40            # DB6: set CG RAM address
    LCD_DDRAM = 0x80            # DB7: set DD RAM address

    LCD_RS_CMD = 0
    LCD_RS_DATA = 1

    LCD_RW_WRITE = 0
    LCD_RW_READ = 1

    def __init__(self, num_lines, num_columns):
        self.num_lines = num_lines
        if self.num_lines > 4:
            self.num_lines = 4
        self.num_columns = num_columns
        if self.num_columns > 40:
            self.num_columns = 40
        self.cursor_x = 0
        self.cursor_y = 0
        self.backlight = True
        self.display_off()
        self.backlight_on()
        self.clear()
        self.hal_write_command(self.LCD_ENTRY_MODE | self.LCD_ENTRY_INC)
        self.hide_cursor()
        self.display_on()

    def clear(self):
        """Clears the LCD display and moves the cursor to the top left
        corner.

        """
        self.hal_write_command(self.LCD_CLR)
        self.hal_write_command(self.LCD_HOME)
        self.cursor_x = 0
        self.cursor_y = 0

    def show_cursor(self):
        """Causes the cursor to be made visible."""
        self.hal_write_command(self.LCD_ON_CTRL | self.LCD_ON_DISPLAY |
                               self.LCD_ON_CURSOR)

    def hide_cursor(self):
        """Causes the cursor to be hidden."""
        self.hal_write_command(self.LCD_ON_CTRL | self.LCD_ON_DISPLAY)

    def blink_cursor_on(self):
        """Turns on the cursor, and makes it blink."""
        self.hal_write_command(self.LCD_ON_CTRL | self.LCD_ON_DISPLAY |
                               self.LCD_ON_CURSOR | self.LCD_ON_BLINK)

    def blink_cursor_off(self):
        """Turns on the cursor, and makes it no blink (i.e. be solid)."""
        self.hal_write_command(self.LCD_ON_CTRL | self.LCD_ON_DISPLAY |
                               self.LCD_ON_CURSOR)

    def display_on(self):
        """Turns on (i.e. unblanks) the LCD."""
        self.hal_write_command(self.LCD_ON_CTRL | self.LCD_ON_DISPLAY)

    def display_off(self):
        """Turns off (i.e. blanks) the LCD."""
        self.hal_write_command(self.LCD_ON_CTRL)

    def backlight_on(self):
        """Turns the backlight on.

        This isn't really an LCD command, but some modules have backlight
        controls, so this allows the hal to pass through the command.
        """
        self.backlight = True
        self.hal_backlight_on()

    def backlight_off(self):
        """Turns the backlight off.

        This isn't really an LCD command, but some modules have backlight
        controls, so this allows the hal to pass through the command.
        """
        self.backlight = False
        self.hal_backlight_off()

    def move_to(self, cursor_x, cursor_y):
        """Moves the cursor position to the indicated position. The cursor
        position is zero based (i.e. cursor_x == 0 indicates first column).
        """
        self.cursor_x = cursor_x
        self.cursor_y = cursor_y
        addr = cursor_x & 0x3f
        if cursor_y & 1:
            addr += 0x40    # Lines 1 & 3 add 0x40
        if cursor_y & 2:
            addr += 0x14    # Lines 2 & 3 add 0x14
        self.hal_write_command(self.LCD_DDRAM | addr)

    def putchar(self, char):
        """Writes the indicated charcter to the LCD at the current cursor
        position, and advances the cursor by one position.
        """
        if self.cursor_x >= self.num_columns or char == '\n':
            self.cursor_x = 0
            self.cursor_y += 1
            if self.cursor_y >= self.num_lines:
                self.cursor_y = 0
            self.move_to(self.cursor_x, self.cursor_y)
        if char != '\n':
            self.hal_write_data(ord(char))
            self.cursor_x += 1

    def putstr(self, string):
        """Write the indicated string to the LCD at the current cursor
        position and advances the cursor position appropriately.
        """
        for char in string:
            self.putchar(char)

    def hal_backlight_on(self):
        """Allows the hal layer to turn the backlight on.

        If desired, a derived HAL class will implement this function.
        """
        pass

    def hal_backlight_off(self):
        """Allows the hal layer to turn the backlight off.

        If desired, a derived HAL class will implement this function.
        """

        pass

    def hal_write_command(self, cmd):
        """Write a command to the LCD.

        It is expected that a derived HAL class will implement this
        function.
        """
        raise NotImplementedError

    def hal_write_data(self, data):
        """Write data to the LCD.

        It is expected that a derived HAL class will implement this
        function.
        """
        raise NotImplementedError
