Hi All,
(Edited to tidy up my original post as per comments below)
I'm trying to monitor temperature using a DHT11. I have it reporting the temperature in Serial Monitor every 2secs but it frequently spikes with huge readings (2147483647ºC). This happens every 10-readings or so, and I'll get a cluster of these spiked readings before normal readings resume.
I've tried increasing the delay between readings but this doesn't do away with the spikes. Does anyone have any ideas on how I might reduce the frequency of these data spikes?
Thanks for your help.
Here's the Sketch:
const int refresh=3;//read every X seconds
boolean showSerial =true;//true or false
unsigned int unit=0;//0=C, 1=F, 2=Humidity
char *title[]={"Temperature","Temperature","Humidity"};
char *unitText[]={"°C","°F","%"};
#include "DHT.h"
#define DHTPIN 2
#define DHTTYPE DHT11 // DHT 11
//#define DHTTYPE DHT22 // DHT 22 (AM2302), AM2321
//#define DHTTYPE DHT21 // DHT 21 (AM2301)
DHT dht(DHTPIN, DHTTYPE);
float temperatureValue,temperatureFValue, humidityValue;//
// ****** DHT settings end (Robojax.com )
#include <WiFi.h>
#include <WiFiClient.h>
#include <WebServer.h>
#include <ESPmDNS.h>
const char *ssid = "mySSID";
const char *password = "myPassword";
WebServer server(80);
void sendTemp() {
//see video https://youtu.be/JXCcmZUmzy8
String page = "<!DOCTYPE html>\n";
page +="<html>\n";
page +="<head>\n";
page +="<title>LivingRoomTemp</title>\n";
page +=" <meta http-equiv='refresh' content='";
page += String(refresh);// how often temperature is read
page +="'/>\n";
page +="<head>\n";
page +="<body>\n";
page +="<h1>Living Room Temperature</h1>\n";
page +="<p style=\"font-size:50px;\">";
page +=title[unit];
page +="<br/>";
page +="<p style=\"color:red; font-size:50px;\">";
if (DHTTYPE ==DHT11){
page += String((int)temperatureValue);
}else{
page += String(temperatureValue, 1);
}
page +=unitText[unit];
page +="</p>\n</body>";
page +="</html>\n";
server.send(200, "text/html",page);
}
void handleNotFound() {
String message = "File Not Found\n\n";
message += "URI: ";
message += server.uri();
message += "\nMethod: ";
message += (server.method() == HTTP_GET) ? "GET" : "POST";
message += "\nArguments: ";
message += server.args();
message += "\n";
for (uint8_t i = 0; i < server.args(); i++) {
message += " " + server.argName(i) + ": " + server.arg(i) + "\n";
}
server.send(404, "text/plain", message);
}
void setup(void) {
// Robojax.com code for ESP32 DHT11 DHT22
dht.begin();
Serial.begin(115200);
WiFi.mode(WIFI_STA);
WiFi.begin(ssid, password);
Serial.println("");
// Wait for connection
while (WiFi.status() != WL_CONNECTED) {
delay(500);
Serial.print(".");
}
Serial.println("");
Serial.print("Connected to ");
Serial.println(ssid);
Serial.print("Open: http://");
Serial.print(WiFi.localIP());
Serial.println(" to read temperature");
if (MDNS.begin("robojaxDHT")) {
Serial.println("MDNS responder started");
Serial.println("or open http://robojaxDHT");
}
server.on("/", sendTemp);
server.on("/inline", []() {
server.send(200, "text/plain", "this works as well");
});
server.onNotFound(handleNotFound);
server.begin();
Serial.println("HTTP server started");
//see video https://youtu.be/JXCcmZUmzy8
}
void loop(void) {
//Robojax.com code for ESP32 DHT11 DHT22
server.handleClient();
temperatureValue = dht.readTemperature();// Read temperature as Celsius (the default)
humidityValue = dht.readHumidity();// Reading humidity
temperatureFValue = dht.readTemperature(true);// Read temperature as Fahrenheit (isFahrenheit = true)
if(unit ==1)
{
temperatureValue =temperatureFValue; //
}else if(unit==3)
{
temperatureValue =humidityValue;
}else{
temperatureValue =temperatureValue;
}
if(showSerial){
Serial.print(title[unit]);
Serial.print(": ");
if (DHTTYPE ==DHT11){
Serial.println((int)temperatureValue);
}else{
Serial.print(temperatureValue,1);
}
}
Serial.println();//just adds new line
delay(2000);// change this to larger value (1000 or more) if you don't need very often reading
// Robojax.com code for ESP32 and DHT11 DHT22
//see video https://youtu.be/JXCcmZUmzy8
