from machine import Pin, I2C, ADC, Timer
import ssd1306
import time

# ESP32 Pin assignment
i2c = I2C(0, scl=Pin(22), sda=Pin(21))
oled = ssd1306.SSD1306_I2C(128, 64, i2c)

# MQ-135 Gas Sensor Pin
mq_pin = ADC(Pin(34))

# Function to read MQ-135 data and convert it to PPM
def read_mq135():
    raw_value = mq_pin.read()
    voltage = raw_value / 4095 * 3.3  # Convert ADC value to voltage
    Rs = (3.3 - voltage) / voltage    # Calculate sensor resistance
    ppm = 446 * (Rs / 10)             # Convert sensor resistance to PPM
    return ppm

# Function to update OLED display
def update_display(timer):
    oled.fill(0)
    ppm_value = read_mq135()
    
    # Display air quality information
    oled.text('Air Quality Monitor', 5, 5)
    oled.text('PPM: {:.2f}'.format(ppm_value), 5, 25)

    # Display additional information
    oled.text('Temperature: 25°C', 5, 45)
    oled.text('Humidity: 50%', 5, 65)

    oled.show()

# Set up a timer to update the display every 5 seconds
timer = Timer(0)
timer.init(period=5000, mode=Timer.PERIODIC, callback=update_display)

# Initial display update
update_display(None)

# You can add more code here for other functionalities or sensors