Adafruit’s library is Broken.
Use it, but replace DHT.cpp with this one: https://raw.githubusercontent.com/adams13x13/DHT-sensor-library/761f4f4fb94c01afc283d0ffbfbfdeed5bb18a44/DHT.cpp
With that, I’m able to use this code to read from my devices:
#include <ESP8266WiFi.h>
#include <WiFiClient.h>
#include <ESP8266WebServer.h>
#include <DHT.h>
#define DHTTYPE DHT11
#define DHTPIN 2
// Replace with your network details
const char* ssid = "Mywifi";
const char* password = "mypassword";
ESP8266WebServer server(80);
// Initialize DHT sensor
// NOTE: For working with a faster than ATmega328p 16 MHz Arduino chip, like an ESP8266,
// you need to increase the threshold for cycle counts considered a 1 or 0.
// You can do this by passing a 3rd parameter for this threshold. It's a bit
// of fiddling to find the right value, but in general the faster the CPU the
// higher the value. The default for a 16mhz AVR is a value of 6. For an
// Arduino Due that runs at 84mhz a value of 30 works.
// This is for the ESP8266 processor on ESP-01
DHT dht(DHTPIN, DHTTYPE, 11); // 11 works fine for ESP8266
float humidity, temp; // Values read from sensor
String webString=""; // String to display
unsigned long previousMillis = 0; // will store last temp was read
const long interval = 2000; // interval at which to read sensor
void setup(void)
{
Serial.begin(115200); // Serial connection from ESP-01 via 3.3v console cable
dht.begin(); // initialize temperature sensor
// Connect to WiFi network
WiFi.mode(WIFI_STA);
WiFi.begin(ssid, password);
Serial.print("\n\r \n\rWorking to connect");
// Wait for connection
while (WiFi.status() != WL_CONNECTED) {
delay(500);
Serial.print(".");
}
Serial.println("");
Serial.println("DHT Weather Reading Server");
Serial.print("Connected to ");
Serial.println(ssid);
Serial.print("IP address: ");
Serial.println(WiFi.localIP());
server.on("/", [](){
gettemperature(); // read sensor
webString="Temperature: "+String((int)temp)+" C Humidity: "+String((int)humidity)+"%" ;
server.send(200, "text/plain", webString);
});
server.begin();
Serial.println("HTTP server started");
}
void loop(void)
{
server.handleClient();
}
void gettemperature() {
unsigned long currentMillis = millis();
if(currentMillis - previousMillis >= interval) {
// save the last time you read the sensor
previousMillis = currentMillis;
// Reading temperature for humidity takes about 250 milliseconds!
// Sensor readings may also be up to 2 seconds 'old' (it's a very slow sensor)
humidity = dht.readHumidity(); // Read humidity (percent)
temp = dht.readTemperature(false); // Read temperature as CELSIUS
// Check if any reads failed and exit early (to try again).
if (isnan(humidity) || isnan(temp)) {
Serial.println("Failed to read from DHT sensor!");
return;
}
}
}After that, I was able to run it in both my ESP-01 with DHT11, as shown here (running from 5v from the breadboard):
Problem is, those thermometers are terribly incorrect! My lab is around 22 degrees. What both sensors show?
So, yeah, that’s it for those things. I will search for something better.
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