一、使用Adafruit_Python_DHT
二、使用升级版CircuitPython-DHT
三、经过C语言编译
上面两种方法都有bug,在获取一次温湿度后,GPIO一直处于高电平,导致下一次读取一直读不到。
因此可使用直接读取信号线的方式。
这里用C来编译,也可以python中直接写。
//
//mydht11.c
//
#include <wiringPi.h>
#include <stdio.h>
#include <stdlib.h>
typedef unsigned char uint8;
typedef unsigned int uint16;
typedef unsigned long uint32;
#define HIGH_TIME 32
int pinNumber = 7; //use gpio1 to read data
uint32 databuf;
uint8 readSensorData(void)
{
uint8 crc;
uint8 i;
pinMode(pinNumber,OUTPUT); // set mode to output
digitalWrite(pinNumber, 1); // output a low level
delayMicroseconds(4);
digitalWrite(pinNumber, 0); // output a high level
delay(25);
digitalWrite(pinNumber, 1); // output a low level
delayMicroseconds(60);
pinMode(pinNumber, INPUT); // set mode to input
pullUpDnControl(pinNumber,PUD_UP);
if(digitalRead(pinNumber)==0) //SENSOR ANS
{
while(!digitalRead(pinNumber)); //wait to high
delayMicroseconds(80);
for(i=0;i<32;i++)
{
while(digitalRead(pinNumber)); //data clock start
while(!digitalRead(pinNumber)); //data start
delayMicroseconds(HIGH_TIME);
databuf*=2;
if(digitalRead(pinNumber)==1) //1
{
databuf++;
}
}
for(i=0;i<8;i++)
{
while(digitalRead(pinNumber)); //data clock start
while(!digitalRead(pinNumber)); //data start
delayMicroseconds(HIGH_TIME);
crc*=2;
if(digitalRead(pinNumber)==1) //1
{
crc++;
}
}
return 1;
}
else
{
return 0;
}
}
int main (void)
{
if (-1 == wiringPiSetup()) {
//printf("Setup wiringPi failed!");
return 1;
}
pinMode(pinNumber, OUTPUT); // set mode to output
digitalWrite(pinNumber, 1); // output a high level
//while(1)
//{
pinMode(pinNumber,OUTPUT); // set mode to output
digitalWrite(pinNumber, 1); // output a high level
//delay(3000);
if(readSensorData())
{
//printf("OK!\n");
//printf("RH:%d.%d\n",(databuf>>24)&0xff,(databuf>>16)&0xff);
//printf("TMP:%d.%d\n",(databuf>>8)&0xff,databuf&0xff);
printf("{\"RH\":\"%d.%d\", \"TMP\":\"%d.%d\"}",(databuf>>24)&0xff,(databuf>>16)&0xff,(databuf>>8)&0xff,databuf&0xff);
databuf=0;
}
else
{
printf("");
databuf=0;
}
//}
return 0;
}
然后编译(注意这里-I使用了wiringPi):
gcc a.c -o dht11 -lwiringPi
然后就可以调用了:
./dht11
之后再Python中调用:
import json
import subprocess
def updateTempHum():
res = json.loads(subprocess.check_output('./dht11').decode('utf-8'))
print(res)
print(res['RH'])
print(res['TMP'])