from time import sleep
from machine import SoftI2C, Pin, ADC
from i2c_lcd import I2cLcd
from simple import MQTTClient
import network
import ujson

# Setup I2C and LCD
i2c = SoftI2C(scl=Pin(22), sda=Pin(21), freq=400000)
lcd = I2cLcd(i2c, 0x27, 2, 16)

# Turbidity sensor using potentiometer 
turbidity_pin = 26
turbidity_adc = ADC(Pin(turbidity_pin))

# pH sensor using potentiometer 
ph_pin = 27
ph_adc = ADC(Pin(ph_pin))

# Config WiFi
WIFI_SSID = "Wokwi-GUEST"
WIFI_PASSWORD = ""

# MQTT Server Parameters
MQTT_CLIENT_ID = ""
MQTT_BROKER = "test.mosquitto.org"
MQTT_PORT = 1883
MQTT_USER = ""
MQTT_PASSWORD = ""
MQTT_TOPIC = "water_quality"

print("Connecting to WiFi", end="")
sta_if = network.WLAN(network.STA_IF)
sta_if.active(True)
sta_if.connect(WIFI_SSID, WIFI_PASSWORD)
while not sta_if.isconnected():
    print(".", end="")
    sleep(0.1)
print(" Connected!")

# Connecting to the MQTT Broker server
print("Connecting to MQTT server... ", end="")
client = MQTTClient(MQTT_CLIENT_ID, MQTT_BROKER, user=MQTT_USER, password=MQTT_PASSWORD)
client.connect()
print("Connected")

# Main Function
water_quality = ""
while True: 
    # Read turbidity level
    turbidity_value = turbidity_adc.read_u16()
    print("Turbidity Level:", turbidity_value)
    
    # Read pH level
    ph_value = ph_adc.read_u16()
    print("pH Level:", ph_value)
    
    # Create JSON message with both readings
    message = ujson.dumps({
        "Turbidity level": turbidity_value,
        "pH level": ph_value
    })
    
    # Publish message if there is a change
    if message != water_quality:
        print("Updated")
        print("Reporting to MQTT topic {}: {}".format(MQTT_TOPIC, message))
        client.publish(MQTT_TOPIC, message)
        water_quality = message
    else: 
        print("No change")
    
    # Display on LCD
    lcd.clear()
    lcd.move_to(0, 0)
    lcd.putstr(f"Turbidity: {turbidity_value}")
    if turbidity_value > 50000:
        print("Water is dirty")
        lcd.move_to(0, 1)
        lcd.putstr("Water is dirty")
    else:
        print("Water is pure")
        lcd.move_to(0, 1)
        lcd.putstr("Water is pure")
    
    sleep(5)
    
    lcd.clear()
    lcd.move_to(0, 0)
    lcd.putstr(f"pH Value: {ph_value}")
    if ph_value > 30000:
        print("pH acceptable")
        lcd.move_to(0, 1)
        lcd.putstr("pH acceptable")
    else:
        print("pH unacceptable")
        lcd.move_to(0, 1)
        lcd.putstr("pH unacceptable")
    
    sleep(8)  # Wait for a few seconds before the next loop









    

main.py

diagram.json

"""Implements a HD44780 character LCD connected via PCF8574 on I2C. 
   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 
# 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 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, 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 initialization. 
        """ 
        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]))

i2c_lcd.py

"""Provides an API for talking to HD44780 compatible character LCDs."""

import time

class LcdApi:
    """Implements the API for talking with HD44780 compatible character LCDs.
    This class only knows what commands to send to the LCD, and not how to 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.implied_newline = False
        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:    # Lines 2 & 3 add number of columns
            addr += self.num_columns
        self.hal_write_command(self.LCD_DDRAM | addr)

    def putchar(self, char):
        """Writes the indicated character to the LCD at the current cursor
        position, and advances the cursor by one position.
        """
        if char == '\n':
            if self.implied_newline:
                # self.implied_newline means we advanced due to a wraparound,
                # so if we get a newline right after that we ignore it.
                self.implied_newline = False
            else:
                self.cursor_x = self.num_columns
        else:
            self.hal_write_data(ord(char))
            self.cursor_x += 1
        if self.cursor_x >= self.num_columns:
            self.cursor_x = 0
            self.cursor_y += 1
            self.implied_newline = (char != '\n')
        if self.cursor_y >= self.num_lines:
            self.cursor_y = 0
        self.move_to(self.cursor_x, self.cursor_y)

    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 custom_char(self, location, charmap):
        """Write a character to one of the 8 CGRAM locations, available
        as chr(0) through chr(7).
        """
        location &= 0x7
        self.hal_write_command(self.LCD_CGRAM | (location << 3))
        self.hal_sleep_us(40)
        for i in range(8):
            self.hal_write_data(charmap[i])
            self.hal_sleep_us(40)
        self.move_to(self.cursor_x, self.cursor_y)

    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

    # This is a default implementation of hal_sleep_us which is suitable
    # for most micropython implementations. For platforms which don't
    # support `time.sleep_us()` they should provide their own implementation
    # of hal_sleep_us in their hal layer and it will be used instead.
    def hal_sleep_us(self, usecs):
        """Sleep for some time (given in microseconds)."""
        time.sleep_us(usecs)  # NOTE this is not part of Standard Python library, specific hal layers will need to override this


lcd_api.py

import usocket as socket
import ustruct as struct
from ubinascii import hexlify


class MQTTException(Exception):
    pass


class MQTTClient:
    def __init__(
        self,
        client_id,
        server,
        port=0,
        user=None,
        password=None,
        keepalive=0,
        ssl=None,
    ):
        if port == 0:
            port = 8883 if ssl else 1883
        self.client_id = client_id
        self.sock = None
        self.server = server
        self.port = port
        self.ssl = ssl
        self.pid = 0
        self.cb = None
        self.user = user
        self.pswd = password
        self.keepalive = keepalive
        self.lw_topic = None
        self.lw_msg = None
        self.lw_qos = 0
        self.lw_retain = False

    def _send_str(self, s):
        self.sock.write(struct.pack("!H", len(s)))
        self.sock.write(s)

    def _recv_len(self):
        n = 0
        sh = 0
        while 1:
            b = self.sock.read(1)[0]
            n |= (b & 0x7F) << sh
            if not b & 0x80:
                return n
            sh += 7

    def set_callback(self, f):
        self.cb = f

    def set_last_will(self, topic, msg, retain=False, qos=0):
        assert 0 <= qos <= 2
        assert topic
        self.lw_topic = topic
        self.lw_msg = msg
        self.lw_qos = qos
        self.lw_retain = retain

    def connect(self, clean_session=True):
        self.sock = socket.socket()
        addr = socket.getaddrinfo(self.server, self.port)[0][-1]
        self.sock.connect(addr)
        if self.ssl:
            self.sock = self.ssl.wrap_socket(self.sock, server_hostname=self.server)
        premsg = bytearray(b"\x10\0\0\0\0\0")
        msg = bytearray(b"\x04MQTT\x04\x02\0\0")

        sz = 10 + 2 + len(self.client_id)
        msg[6] = clean_session << 1
        if self.user:
            sz += 2 + len(self.user) + 2 + len(self.pswd)
            msg[6] |= 0xC0
        if self.keepalive:
            assert self.keepalive < 65536
            msg[7] |= self.keepalive >> 8
            msg[8] |= self.keepalive & 0x00FF
        if self.lw_topic:
            sz += 2 + len(self.lw_topic) + 2 + len(self.lw_msg)
            msg[6] |= 0x4 | (self.lw_qos & 0x1) << 3 | (self.lw_qos & 0x2) << 3
            msg[6] |= self.lw_retain << 5

        i = 1
        while sz > 0x7F:
            premsg[i] = (sz & 0x7F) | 0x80
            sz >>= 7
            i += 1
        premsg[i] = sz

        self.sock.write(premsg, i + 2)
        self.sock.write(msg)
        # print(hex(len(msg)), hexlify(msg, ":"))
        self._send_str(self.client_id)
        if self.lw_topic:
            self._send_str(self.lw_topic)
            self._send_str(self.lw_msg)
        if self.user:
            self._send_str(self.user)
            self._send_str(self.pswd)
        resp = self.sock.read(4)
        assert resp[0] == 0x20 and resp[1] == 0x02
        if resp[3] != 0:
            raise MQTTException(resp[3])
        return resp[2] & 1

    def disconnect(self):
        self.sock.write(b"\xe0\0")
        self.sock.close()

    def ping(self):
        self.sock.write(b"\xc0\0")

    def publish(self, topic, msg, retain=False, qos=0):
        pkt = bytearray(b"\x30\0\0\0")
        pkt[0] |= qos << 1 | retain
        sz = 2 + len(topic) + len(msg)
        if qos > 0:
            sz += 2
        assert sz < 2097152
        i = 1
        while sz > 0x7F:
            pkt[i] = (sz & 0x7F) | 0x80
            sz >>= 7
            i += 1
        pkt[i] = sz
        # print(hex(len(pkt)), hexlify(pkt, ":"))
        self.sock.write(pkt, i + 1)
        self._send_str(topic)
        if qos > 0:
            self.pid += 1
            pid = self.pid
            struct.pack_into("!H", pkt, 0, pid)
            self.sock.write(pkt, 2)
        self.sock.write(msg)
        if qos == 1:
            while 1:
                op = self.wait_msg()
                if op == 0x40:
                    sz = self.sock.read(1)
                    assert sz == b"\x02"
                    rcv_pid = self.sock.read(2)
                    rcv_pid = rcv_pid[0] << 8 | rcv_pid[1]
                    if pid == rcv_pid:
                        return
        elif qos == 2:
            assert 0

    def subscribe(self, topic, qos=0):
        assert self.cb is not None, "Subscribe callback is not set"
        pkt = bytearray(b"\x82\0\0\0")
        self.pid += 1
        struct.pack_into("!BH", pkt, 1, 2 + 2 + len(topic) + 1, self.pid)
        # print(hex(len(pkt)), hexlify(pkt, ":"))
        self.sock.write(pkt)
        self._send_str(topic)
        self.sock.write(qos.to_bytes(1, "little"))
        while 1:
            op = self.wait_msg()
            if op == 0x90:
                resp = self.sock.read(4)
                # print(resp)
                assert resp[1] == pkt[2] and resp[2] == pkt[3]
                if resp[3] == 0x80:
                    raise MQTTException(resp[3])
                return

    # Wait for a single incoming MQTT message and process it.
    # Subscribed messages are delivered to a callback previously
    # set by .set_callback() method. Other (internal) MQTT
    # messages processed internally.
    def wait_msg(self):
        res = self.sock.read(1)
        self.sock.setblocking(True)
        if res is None:
            return None
        if res == b"":
            raise OSError(-1)
        if res == b"\xd0":  # PINGRESP
            sz = self.sock.read(1)[0]
            assert sz == 0
            return None
        op = res[0]
        if op & 0xF0 != 0x30:
            return op
        sz = self._recv_len()
        topic_len = self.sock.read(2)
        topic_len = (topic_len[0] << 8) | topic_len[1]
        topic = self.sock.read(topic_len)
        sz -= topic_len + 2
        if op & 6:
            pid = self.sock.read(2)
            pid = pid[0] << 8 | pid[1]
            sz -= 2
        msg = self.sock.read(sz)
        self.cb(topic, msg)
        if op & 6 == 2:
            pkt = bytearray(b"\x40\x02\0\0")
            struct.pack_into("!H", pkt, 2, pid)
            self.sock.write(pkt)
        elif op & 6 == 4:
            assert 0
        return op

    # Checks whether a pending message from server is available.
    # If not, returns immediately with None. Otherwise, does
    # the same processing as wait_msg.
    def check_msg(self):
        self.sock.setblocking(False)
        return self.wait_msg()