ESP8266之DHT11串口打印温湿度
模块：唯倚SIOT-1物联网模块
SDK版本:ESP8266_RTOS_SDK-3.0
开发环境：wsl+vscode
功能模块：wifi，tcp_client,dht11
由于sdk不断更新，使得网上很多代码都无法使用，本代码sdk2.0与sdk3.0适用，不兼容老的sdk。
关于dht11我们可以查看它的中文说明书，了解其数据总线通信的时序图
本文代码参考了RTOS V2.0 驱动DHT11 读取温度湿度值并作为TCP客户端发送到PC
不过这里只采用串口查看dht11的温度湿度。
主要思路是利用gpio2给传感器发送特定信号，然后dht11返回开始信号，传输数据。并对返回数据进行转换处理。
#include "freertos/FreeRTOS.h"
#include "freertos/task.h"
#include "freertos/event_groups.h"
#include "rom/ets_sys.h"
#include "driver/gpio.h"
#include <string.h>
#define DHT_MAXTIMINGS 10000
#define DHT_BREAKTIME 20
#define DHT_MAXCOUNT 32000
struct dht_sensor_data {
float temperature;
float humidity;
};//定义一个变量
struct dht_sensor_data reading ;
float scale_humidity(int *data)
{
return data[0];
}
float scale_temperature(int *data)
{
return data[2];
}
float get_temperature()
{
return reading.temperature;
}
float get_humidity()
{
return reading.humidity;
}
void DHT11_read(void)
{
int counter = 0;
int laststate = 1;
int i = 0;
int j = 0;
int checksum = 0;
int data[100];
data[0] = data[1] = data[2] = data[3] = data[4] = 0;
gpio_config_t io_conf;
io_conf.intr_type = GPIO_INTR_DISABLE;
io_conf.mode = GPIO_MODE_OUTPUT;
io_conf.pin_bit_mask = ((1ULL<<2) | (1ULL<<2));
io_conf.pull_down_en = 0;
io_conf.pull_up_en = 1;
gpio_config(&io_conf);
gpio_set_level(2, 1);
vTaskDelay(250 / portTICK_PERIOD_MS);
gpio_set_level(2, 0);
vTaskDelay(20 / portTICK_PERIOD_MS);
gpio_set_level(2, 1);
gpio_set_direction(2,GPIO_MODE_INPUT);
os_delay_us(10);
while (gpio_get_level(2) == 1 && i < DHT_MAXCOUNT)
{
os_delay_us(1);
i++;
}
if(i == DHT_MAXCOUNT)//读取失败,可能是DHT11还未准备好
return;
for (i = 0; i < DHT_MAXTIMINGS; i++)
{
counter = 0;
while (gpio_get_level(2) == laststate)
{
counter++;
os_delay_us(1);
if (counter == 1000)
break;
}
laststate = gpio_get_level(2);
if (counter == 1000)
break;
if ((i>3) && (i%2 == 0))
{
data[j/8] <<= 1;
if (counter > DHT_BREAKTIME)
data[j/8] |= 1;
j++;
}
}
if (j >= 39) {
checksum = (data[0] + data[1] + data[2] + data[3]) & 0xFF;
if (data[4] == checksum)
{
reading.temperature = scale_temperature(data);
reading.humidity = scale_humidity(data);
}
}
}
void app_main(void)
{
while(1)
{
DHT11_read();
printf("[DHT11]Temp:%d,Hud:%d\n",(int)(get_temperature()),(int)(get_humidity()));
vTaskDelay(5000 / portTICK_PERIOD_MS);
}
}