mqtt - 我正在编写一个代码来读取 DHT11 值并控制 4 个继电器但温度。传感器每次都向我显示“nan”
问题描述
我正在使用 NodeMCU (ESP8266-12E) 进行温度读数的家庭自动化项目。我正在使用带有 DHT11.h 库的 DHT11 传感器,但我的温度传感器向我显示“nan”而不是任何值。我不知道我在哪里落后。
我的代码如下:
#include "DHT.h" // including the library of DHT11 temperature and humidity sensor
#define DHTTYPE DHT11 // DHT 11
#include <ESP8266WiFi.h>
#include "Adafruit_MQTT.h"
#include "Adafruit_MQTT_Client.h"
#define Relay1 D1
#define Relay2 D2
#define Relay3 D3
#define Relay4 D4
#define DHTPIN D0
DHT dht(DHTPIN, DHTTYPE);
float temp_f;
String webString = "";
unsigned long previousMillis = 0;
const long interval = 2300;
#define WLAN_SSID "internet" // Your SSID
#define WLAN_PASS "*********" // Your password
/************************* Adafruit.io Setup *********************************/
#define AIO_SERVER "io.adafruit.com" //Adafruit Server
#define AIO_SERVERPORT 1883
#define AIO_USERNAME "foo" // Username
#define AIO_KEY "bar" // Auth Key
//WIFI CLIENT
WiFiClient client;
Adafruit_MQTT_Client mqtt(&client, AIO_SERVER, AIO_SERVERPORT, AIO_USERNAME, AIO_KEY);
// Setup a feed called 'photocell' for publishing.
// Notice MQTT paths for AIO follow the form: <username>/feeds/<feedname>
const char TEMP_FEED[] PROGMEM = AIO_USERNAME "/feeds/photocell";
Adafruit_MQTT_Publish photocell = Adafruit_MQTT_Publish(&mqtt, AIO_USERNAME"/feeds/photocell");
Adafruit_MQTT_Subscribe Light1 = Adafruit_MQTT_Subscribe(&mqtt, AIO_USERNAME"/feeds/Relay1"); // Feeds name should be same everywhere
Adafruit_MQTT_Subscribe Light2 = Adafruit_MQTT_Subscribe(&mqtt, AIO_USERNAME"/feeds/Relay2");
Adafruit_MQTT_Subscribe Light3 = Adafruit_MQTT_Subscribe(&mqtt, AIO_USERNAME"/feeds/Relay3");
Adafruit_MQTT_Subscribe Light4 = Adafruit_MQTT_Subscribe(&mqtt, AIO_USERNAME"/feeds/Relay4");
void MQTT_connect();
void setup()
{
Serial.begin(115200);
delay(10);
dht.begin();
// Print temperature sensor details.
pinMode(Relay1, OUTPUT);
pinMode(Relay2, OUTPUT);
pinMode(Relay3, OUTPUT);
pinMode(Relay4, OUTPUT);
// Connect to WiFi access point.
Serial.println();
Serial.println();
Serial.print("Connecting to ");
Serial.println(WLAN_SSID);
WiFi.begin(WLAN_SSID, WLAN_PASS);
while (WiFi.status() != WL_CONNECTED) {
delay(500);
Serial.print(".");
}
Serial.println();
Serial.println("WiFi connected");
Serial.println("IP address: ");
Serial.println(WiFi.localIP());
temp_f = dht.readTemperature(true);
Serial.println();
Serial.print("Initial Temp: ");
Serial.println(temp_f);
Serial.println();
mqtt.subscribe(&Light1);
mqtt.subscribe(&Light3);
mqtt.subscribe(&Light2);
mqtt.subscribe(&Light4);
}
int delayTime = 300000; //Wait 5 minutes before sending data to web
int startDelay = 0;
void loop()
{
MQTT_connect();
if (millis() - startDelay < delayTime) {
Serial.println("waiting delaytime");
}
else {
temp_f = dht.readTemperature(true); //Get temp in Farenheit
startDelay = millis();
Serial.print(F("\nSending temp: "));
Serial.print(temp_f);
Serial.print("...");
if (!photocell.publish(temp_f)) { //Publish to Adafruit
Serial.println(F("Failed"));
}
else {
Serial.println(F("Sent!"));
}
}
/* //int t = dht.readTemperature(true);
// t = t/100000000;
Serial.print(F("\nSending photocell val "));
Serial.print(t);
Serial.print("...");
if (! photocell.publish(t)) {
Serial.println(F("Failed"));
} else {
Serial.println(F("OK!"));
}*/
Adafruit_MQTT_Subscribe* subscription;
while ((subscription = mqtt.readSubscription(2000))) {
if (subscription == &Light1) {
Serial.print(F("Got: "));
Serial.println((char*)Light1.lastread);
int Light1_State = atoi((char*)Light1.lastread);
digitalWrite(Relay1, Light1_State);
}
if (subscription == &Light2) {
Serial.print(F("Got: "));
Serial.println((char*)Light2.lastread);
int Light2_State = atoi((char*)Light2.lastread);
digitalWrite(Relay2, Light2_State);
}
if (subscription == &Light3) {
Serial.print(F("Got: "));
Serial.println((char*)Light3.lastread);
int Light3_State = atoi((char*)Light3.lastread);
digitalWrite(Relay3, Light3_State);
}
if (subscription == &Light4) {
Serial.print(F("Got: "));
Serial.println((char*)Light4.lastread);
int Light4_State = atoi((char*)Light4.lastread);
digitalWrite(Relay4, Light4_State);
}
}
// this is our 'wait for incoming subscription packets and callback em' busy subloop
// try to spend your time here:
mqtt.processPackets(500);
}
void MQTT_connect()
{
int8_t ret;
if (mqtt.connected()) {
return;
}
Serial.print("Connecting to MQTT... ");
uint8_t retries = 3;
while ((ret = mqtt.connect()) != 0) {
Serial.println(mqtt.connectErrorString(ret));
Serial.println("Retrying MQTT connection in 5 seconds...");
mqtt.disconnect();
delay(5000);
retries--;
if (retries == 0) {
while (1);
}
}
Serial.println("MQTT Connected!");
}
解决方案
您尝试在 setup() 中读取温度和湿度。但是您需要在dht.begin之后和读取之前在最小值处等待 2 秒,因为传感器读数也可能长达 2 秒
所以在第一次阅读之前添加延迟(2000) ..
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