stm32 检测温度，DHT11，读取总是0000

Question

stm32 检测温度，用的是DHT11，读取显示总是0000，是程序的问题么？

#include "stm32f10x.h"                  // Device header
#include "Delay.h"

uint16_t Time = 0;

void DHT11_Start(void)       //引脚发送起始信号
{                 
    RCC_APB2PeriphClockCmd(RCC_APB2Periph_GPIOB, ENABLE);        //开启GPIOB的时钟
    
    GPIO_InitTypeDef GPIO_InitStructure;
    GPIO_InitStructure.GPIO_Mode = GPIO_Mode_Out_PP;//将PB0引脚初始化为推挽输出
    GPIO_InitStructure.GPIO_Pin = GPIO_Pin_0;
    GPIO_InitStructure.GPIO_Speed = GPIO_Speed_50MHz;
    GPIO_Init(GPIOB, &GPIO_InitStructure);    

    GPIO_ResetBits(GPIOB, GPIO_Pin_0);//PB0低电平18毫秒
    Delay_ms(18);
        
    GPIO_SetBits(GPIOB, GPIO_Pin_0);//PB0高电平40微秒
    Delay_us(40);
}

void DHT11_Response(void)//手动应答成功
{    
    RCC_APB2PeriphClockCmd(RCC_APB2Periph_GPIOB, ENABLE);
    GPIO_InitTypeDef GPIO_InitStructure;
    GPIO_InitStructure.GPIO_Mode = GPIO_Mode_IPU;//将PB0引脚初始化为上拉输入
    GPIO_InitStructure.GPIO_Pin = 0;
    GPIO_InitStructure.GPIO_Speed = GPIO_Speed_50MHz;
    GPIO_Init(GPIOB, &GPIO_InitStructure);
    
    while((GPIO_ReadInputDataBit(GPIOB, GPIO_Pin_0) == 0) && (Time < 100))//B0口读取输入=0 100微秒
    {
        Time ++ ;
        Delay_us(1);
    }
    Time = 0;
    
    while((GPIO_ReadInputDataBit(GPIOB, GPIO_Pin_0) == 1) && (Time < 100))//B0口读取输入=1 100微秒
    {
        Time ++ ;
        Delay_us(1);
    }
    Time = 0;    
}

uint8_t DHT11_Read_Byte(void)//读取一个字节
{
    uint8_t i = 0;
    
    uint8_t Data = 0;
    
    for (i = 0; i < 8; i ++)
    {
        RCC_APB2PeriphClockCmd(RCC_APB2Periph_GPIOB, ENABLE);    //开启GPIOA的时钟
        
        GPIO_InitTypeDef GPIO_InitStructure;
        GPIO_InitStructure.GPIO_Mode = GPIO_Mode_IPU;//软件实现5K上拉电阻
        GPIO_InitStructure.GPIO_Pin = 0;
        GPIO_InitStructure.GPIO_Speed = GPIO_Speed_50MHz;
        GPIO_Init(GPIOB, &GPIO_InitStructure);    //调用库函数初始化GPIOB    
        
        while((GPIO_ReadInputDataBit(GPIOB, GPIO_Pin_0) == 0) && (Time < 50))//50微秒的低电平
        {
            Time ++ ;
            Delay_us(1);
        }
        Time = 0;
        
        Data <<= 1;//数据左移一位
        Delay_us(40);//等40微秒26~28秒高电平是0,70微秒的高电平是1
        
        if(GPIO_ReadInputDataBit(GPIOB, GPIO_Pin_0) == 1)
        {
            Data |= 0x01;//数据低位补充
            
            while((GPIO_ReadInputDataBit(GPIOB, GPIO_Pin_0) == 1) && (Time < 30))    
            {
                Time ++ ;
                Delay_us(1);
            }
            Time = 0;
        }
    }    
    return Data;
}

void DHT11_Read_Data(uint8_t *humi, uint8_t *temp)
{
    uint8_t i;
    uint8_t DATA[5] = {0, 0, 0, 0, 0};
    
    DHT11_Start();
    DHT11_Response();
    
    for (i = 0; i < 5; i ++)
    {
        DATA[i] = DHT11_Read_Byte();
    }
    
    Delay_ms(1);
    
    if (DATA[0] + DATA[1] + DATA[2] + DATA[3] == DATA[4])
    {
        *humi = DATA[0];
        *temp = DATA[2];
    }
    else
    {
        for (i = 0; i < 5; i ++)
        {
            DATA[i] = 0;
        }
    }
    
}

DHT11.h

#ifndef __DHT11_H
#define __DHT11_H

uint8_t DHT11_Read_Byte(void);
void DHT11_Read_Data(uint8_t *humi, uint8_t *temp);

#endif

main.c

#include "stm32f10x.h"        
#include "OLED.h"                 
#include "Delay.h"                            
#include "DH11.h"                 

uint8_t humi, temp, KeyNum;

int main(void)
{
    OLED_Init();

    while (1)
    {
        DHT11_Read_Data(&humi, &temp);    
        OLED_ShowNum(0, 0, temp, 4, OLED_8X16);
        OLED_ShowNum(60, 0, humi, 4, OLED_8X16); 
        OLED_Update(); 
    }
}

Answer 1

检查一下是否给开发板单独供电，看下延时函数是否正确，你的DHT11的型号和参数是否与你的代码一致，尝试去掉DHT11的初始化函数，只在DHT11_Start函数中配置数据引脚的模式。