We’ve had some issues at the office with milk going sour, usually over weekends. This long weekend was extra bad as Tuesday morning we had to bin 7 x 4pint bottles of milk that had all turned to nasty smelling cheese over the course of the 3 day weekend.
It was suggested that we put a thermometer in the fridge, sure it’ll work, but it can only show you what the temp is NOW and not over time. Soooo being a geek and very new to the world of Arduino, I knew I had to find a way.
Click here to see Photos of devices used
Enter the ESP8266 12-E and a DHT22 plus ThingSpeak. I found the code I was looking for, thanks very much to “Chispa” over at #GoChispaGo. The code only need a couple of minor tweaks plus a load of translating since his was in Spanish 😀
The code is pretty straightforward (says a guy that really doesn’t have any programming experience with Arduino’s).
Building the project was simple, the ESP8266 is powered by a USB cable and phone charger plugged into the wall and the DHT22 is plugged into 5vdc, ground and pin D4 on the ESP8266 board.
I got it working just fine though so I’m well pleased about that.
The data is logged to a chart: https://thingspeak.com/channels/321768
And the code used is as follows.
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#include <DHT.h> #include <ESP8266WiFi.h> // Introducir a continuación tus datos de ThingSpeak y red WiFi String apiKey = "YOUR THINGSPEAK API KEY"; const char* ssid = "your-SSID"; const char* password = "your-PASSWORD"; const char* server = "api.thingspeak.com"; // Time to sleep (in seconds): //const int sleepTimeS = 60; #define DHTPIN D4 #define DHTTYPE DHT22 DHT dht(DHTPIN, DHTTYPE); WiFiClient client; void setup() { Serial.begin(115200); delay(10); dht.begin(); WiFi.begin(ssid, password); Serial.println(); Serial.println(); Serial.print("Connecting to "); Serial.println(ssid); WiFi.begin(ssid, password); while (WiFi.status() != WL_CONNECTED) { delay(500); Serial.print("."); } Serial.println(""); Serial.println("WiFi connected"); } void loop() { delay(2000); float h = dht.readHumidity(); float t = dht.readTemperature(); if (isnan(h) || isnan(t)) { Serial.println("DHT sensor reading failure !!!"); return; } if (client.connect(server,80)) { String postStr = apiKey; postStr +="&field1="; postStr += String(t); postStr +="&field2="; postStr += String(h); postStr += "\r\n\r\n"; client.print("POST /update HTTP/1.1\n"); client.print("Host: api.thingspeak.com\n"); client.print("Connection: close\n"); client.print("X-THINGSPEAKAPIKEY: "+apiKey+"\n"); client.print("Content-Type: application/x-www-form-urlencoded\n"); client.print("Content-Length: "); client.print(postStr.length()); client.print("\n\n"); client.print(postStr); Serial.print("Temperature: "); Serial.print(t); Serial.print("*C Humidity: "); Serial.print(h); Serial.print("%"); Serial.println("---->>>> Sent data to ThingSpeak"); } client.stop(); //Sleep // Serial.println("ESP8266 in sleep mode"); // ESP.deepSleep(sleepTimeS * 1000000,WAKE_RF_DEFAULT); Serial.println("Waiting 60 seconds... "); delay(60000); } |
Feel free to take the code and play away for your own needs.
Check the gasket seal around the door!
Mostly the problem is that the fridge is pretty empty with generally only about 4 or 5 bottles of milk (4 pint each). Fridges really need to be full or they’re not efficient at all.