MQ-7 esp32 micropython

MQ-7 Датчик углекислого газа.

 

ESP32 > MQ-2

GND > GND

3.3 > VCC

D4 > A0

D15 >  D0

В начале датчик откалибруется, желательно на чистом воздухе.

main.py    

from machine import Pin, ADC
import time
import math

class MQ7:
    def __init__(self, analog_pin, digital_pin=None):
        self.analog_pin = ADC(Pin(analog_pin))
        self.analog_pin.atten(ADC.ATTN_11DB)  # 0-3.3V range
        
        if digital_pin:
            self.digital_pin = Pin(digital_pin, Pin.IN)
        else:
            self.digital_pin = None
            
        # Calibration values (adjust based on your environment)
        self.R0 = 10.0  # Sensor resistance in clean air
        
    def read_analog(self):
        """Read analog value (0-4095)"""
        return self.analog_pin.read()
    
    def read_voltage(self):
        """Read voltage value (0-3.3V)"""
        return (self.analog_pin.read() / 4095) * 3.3
    
    def read_digital(self):
        """Read digital value (if digital pin connected)"""
        if self.digital_pin:
            return self.digital_pin.value()
        return None
    
    def read_ppm(self):
        """Estimate CO concentration in PPM"""
        # MQ-7 requires heating cycles
        # This is a simplified calculation - needs proper calibration
        sensor_voltage = self.read_voltage()
        rs = (3.3 - sensor_voltage) / sensor_voltage * 5.0  # Assuming RL=5K
        ratio = rs / self.R0
        
        # Approximate PPM calculation for MQ-7
        ppm = 10 ** ((math.log10(ratio) - 0.8) / -0.4)
        return ppm

# Initialize sensor
mq7 = MQ7(4, 15)  # Analog on GPIO 36, Digital on GPIO 39

while True:
    analog_value = mq7.read_analog()
    voltage = mq7.read_voltage()
    digital_value = mq7.read_digital()
    ppm = mq7.read_ppm()
    
    print(f"Analog: {analog_value}, Voltage: {voltage:.2f}V, Digital: {digital_value}, PPM: {ppm:.2f}")
    time.sleep(2)