from machine import ADC, Pin
import time

# 配置引脚 - 可根据实际连接修改
MQ2_ANALOG_PIN = 34  # 模拟输入引脚
MQ2_DIGITAL_PIN = 2  # 数字输入引脚(如果使用数字输出)
LED_ALARM_PIN = 13   # 报警LED输出引脚

# 初始化传感器和外设
mq2_analog = ADC(Pin(MQ2_ANALOG_PIN))
mq2_digital = Pin(MQ2_DIGITAL_PIN, Pin.IN)
led_alarm = Pin(LED_ALARM_PIN, Pin.OUT)

# 设置ADC参数(ESP32特定)
mq2_analog.atten(ADC.ATTN_11DB)  # 配置为3.3V范围
mq2_analog.width(ADC.WIDTH_12BIT)  # 12位分辨率(0-4095)

# 校准参数 - 建议实际环境中校准
RL_VALUE = 5  # 负载电阻值(kΩ)
RO_CLEAN_AIR_FACTOR = 9.83  # MQ-2在洁净空气中的Ro值

# 气体类型常量
GAS_LPG = 0
GAS_CO = 1
GAS_SMOKE = 2

# 曲线系数 - 根据传感器datasheet
class Curve:
    def __init__(self, a, b):
        self.a = a  # 斜率
        self.b = b  # Y轴截距

# 不同气体的曲线参数
CURVES = {
    GAS_LPG: Curve(-0.45, 2.95),
    GAS_CO: Curve(-0.38, 3.21),
    GAS_SMOKE: Curve(-0.42, 3.54)
}

# 报警阈值(ppm)
ALARM_THRESHOLDS = {
    GAS_LPG: 1000,
    GAS_CO: 50,
    GAS_SMOKE: 500
}

def calibrate_ro_in_clean_air(samples=10, delay=1):
    """在洁净空气中校准Ro值"""
    print("开始洁净空气校准，请确保环境空气清新...")
    total = 0
    for i in range(samples):
        adc_value = mq2_analog.read()
        voltage = adc_value * (3.3 / 4095)
        rs_value = ((3.3 / voltage) - 1) * RL_VALUE
        total += rs_value
        print(f"采样 {i+1}/{samples}: Rs = {rs_value:.2f} kΩ")
        time.sleep(delay)
    
    average_rs = total / samples
    ro_value = average_rs / RO_CLEAN_AIR_FACTOR
    print(f"校准完成! Ro = {ro_value:.2f} kΩ")
    return ro_value

def get_correction_factor(temperature, humidity):
    """根据环境温湿度修正读数"""
    # 此函数基于传感器特性曲线，需根据实际传感器调整
    if temperature < 20:
        return 0.98
    elif temperature < 30:
        return 1.0
    else:
        return 1.02

def get_rs_ro_ratio(rs_value, ro_value):
    """计算RS/RO比值"""
    return rs_value / ro_value

def get_gas_ppm(rs_ro_ratio, gas_type):
    """根据RS/RO比值和气体类型计算浓度(ppm)"""
    curve = CURVES[gas_type]
    return 10 ** ((rs_ro_ratio - curve.b) / curve.a)

def read_mq2(ro_value):
    """读取MQ2传感器数据"""
    # 读取模拟值
    adc_value = mq2_analog.read()
    
    # 转换为电压
    voltage = adc_value * (3.3 / 4095)
    
    # 计算RS值(传感器电阻)
    rs_value = ((3.3 / voltage) - 1) * RL_VALUE
    
    # 应用温湿度修正(实际应用中应从DHT传感器读取)
    temperature = 25  # 示例值
    humidity = 60     # 示例值
    correction_factor = get_correction_factor(temperature, humidity)
    rs_corrected = rs_value / correction_factor
    
    # 计算不同气体浓度
    rs_ro_ratio = get_rs_ro_ratio(rs_corrected, ro_value)
    lpg_ppm = get_gas_ppm(rs_ro_ratio, GAS_LPG)
    co_ppm = get_gas_ppm(rs_ro_ratio, GAS_CO)
    smoke_ppm = get_gas_ppm(rs_ro_ratio, GAS_SMOKE)
    
    # 读取数字输出
    digital_value = mq2_digital.value()
    
    return {
        "adc_value": adc_value,
        "voltage": voltage,
        "rs_value": rs_value,
        "digital_value": digital_value,
        "temperature": temperature,
        "humidity": humidity,
        "gas_concentrations": {
            "lpg": lpg_ppm,
            "co": co_ppm,
            "smoke": smoke_ppm
        }
    }

def check_alarms(results):
    """检查是否触发任何报警"""
    alarms = []
    for gas_type, ppm in results["gas_concentrations"].items():
        gas_name = {GAS_LPG: "LPG", GAS_CO: "CO", GAS_SMOKE: "烟雾"}.get(gas_type, "未知气体")
        threshold = ALARM_THRESHOLDS.get(gas_type, float('inf'))
        
        if ppm > threshold:
            alarms.append(f"{gas_name}浓度过高: {ppm:.2f} ppm")
    
    return alarms

# 主程序
try:
    print("MQ-2传感器测试程序启动...")
    # 校准Ro值(首次使用或环境变化时建议运行)
    # ro_value = calibrate_ro_in_clean_air()
    # 或者使用预设值
    ro_value = 10.0  # 根据实际校准结果修改
    
    print("传感器预热中，请等待...")
    time.sleep(20)  # MQ-2传感器需要预热时间
    
    while True:
        result = read_mq2(ro_value)
        
        # 打印结果
        print("\n===== MQ-2传感器读数 =====")
        print(f"ADC值: {result['adc_value']}")
        print(f"电压值: {result['voltage']:.2f}V")
        print(f"传感器电阻(Rs): {result['rs_value']:.2f} kΩ")
        print(f"数字输出: {'有烟雾' if result['digital_value'] else '无烟雾'}")
        
        # 打印气体浓度
        print("\n气体浓度:")
        for gas_type, ppm in result["gas_concentrations"].items():
            gas_name = {GAS_LPG: "LPG", GAS_CO: "CO", GAS_SMOKE: "烟雾"}.get(gas_type, "未知气体")
            print(f"  {gas_name}: {ppm:.2f} ppm")
        
        # 检查报警
        alarms = check_alarms(result)
        if alarms:
            print("\n⚠️ 警告:")
            for alarm in alarms:
                print(f"- {alarm}")
            led_alarm.on()  # 触发报警LED
        else:
            led_alarm.off()  # 关闭报警LED
        
        time.sleep(1)  # 每秒读取一次

except KeyboardInterrupt:
    print("\n程序已停止")
finally:
    led_alarm.off()  # 确保程序退出时LED关闭