DHT11的驱动代码

以下是DHT11的驱动代码，使用C语言编写：

#include <stdio.h>
#include <wiringPi.h>

#define MAX_TIMINGS 85
#define DHT_PIN 7 // 使用wiringPi编号，对应树莓派的GPIO4

int data[5] = { 0, 0, 0, 0, 0 };

void read_dht11_dat()
{
    uint8_t laststate = HIGH;
    uint8_t counter = 0;
    uint8_t j = 0, i;

    data[0] = data[1] = data[2] = data[3] = data[4] = 0;

    pinMode(DHT_PIN, OUTPUT);
    digitalWrite(DHT_PIN, LOW);
    delay(18);
    digitalWrite(DHT_PIN, HIGH);
    delayMicroseconds(30);
    pinMode(DHT_PIN, INPUT);

    for (i = 0; i < MAX_TIMINGS; i++)
    {
        counter = 0;
        while (digitalRead(DHT_PIN) == laststate)
        {
            counter++;
            delayMicroseconds(1);
            if (counter == 255)
            {
                break;
            }
        }

        laststate = digitalRead(DHT_PIN);

        if (counter == 255)
            break;

        if ((i >= 4) && (i % 2 == 0))
        {
            data[j / 8] <<= 1;
            if (counter > 16)
                data[j / 8] |= 1;
            j++;
        }
    }

    if ((j >= 40) &&
        (data[4] == ((data[0] + data[1] + data[2] + data[3]) & 0xFF)))
    {
        printf("Humidity = %d.%d %% Temperature = %d.%d *C\n", 
            data[0], data[1], data[2], data[3]);
    }
    else
    {
        printf("Data not good, skip\n");
    }
}

int main(void)
{
    printf("DHT11 temperature and humidity sensor\n");

    if (wiringPiSetup() == -1)
        exit(1);

    while (1)
    {
        read_dht11_dat();
        delay(1000); // 每隔1秒读取一次
    }

    return 0;
}

这段代码使用wiringPi库来控制树莓派的GPIO口，读取DHT11传感器的湿度和温度数据。需要注意的是，DHT11传感器的数据线在读取之前需要拉低一段时间，然后再拉高，等待传感器的响应。之后，通过读取数据线的高低电平来解析传感器传回的数据。最后对数据进行校验，判断数据是否正确。