• Mood: hot

Arduino thermometer

What with the glorious sunny weather, I wondered how hot my flat actually gets. It's certainly felt far too warm recently.

Now, the sensible way to find out is to go and buy a thermometer. But Robert Days are closed for the evening. So instead I dug out an Arduino kit I was given for my birthday (Elegoo's "The Most Complete Starter Kit for the Mega 2560") and set to work...



The answer: 27°C!

I'm using a DHT11 combined temperature and humidity sensor and a generic LCD display showing the results, running off of a 9V battery so I can wander around with it. The nice thing about Arduino development is there are libraries for everything, so there's surprisingly little code behind this:

// Based off sample lessons 12 (DHT11) and 22 (LCD) // DHT11 #include <dht_nonblocking.h> #define DHT_SENSOR_TYPE DHT_TYPE_11 static const int DHT_SENSOR_PIN = 2; DHT_nonblocking dht_sensor( DHT_SENSOR_PIN, DHT_SENSOR_TYPE ); /* * Poll for a measurement, keeping the state machine alive. Returns * true if a measurement is available. */ static bool measure_environment( float *temperature, float *humidity ) { static unsigned long measurement_timestamp = millis( ); /* Measure once every four seconds. */ if( millis( ) - measurement_timestamp > 3000ul ) { if( dht_sensor.measure( temperature, humidity ) == true ) { measurement_timestamp = millis( ); return( true ); } } return( false ); } // LCD // include the library code: #include <LiquidCrystal.h> // initialize the library with the numbers of the interface pins LiquidCrystal lcd(7, 8, 9, 10, 11, 12); void setup() { // set up the LCD's number of columns and rows: lcd.begin(16, 2); // Print a message to the LCD. //01234567890123456 lcd.print("Temp: "); lcd.setCursor(0, 1); //01234567890 lcd.print("Humidity: "); } void loop() { float temperature; float humidity; /* Measure temperature and humidity. If the functions returns true, then a measurement is available. */ if( measure_environment( &temperature, &humidity ) == true ) { Serial.print( "T = " ); Serial.print( temperature, 1 ); Serial.print( " deg. C, H = " ); Serial.print( humidity, 1 ); Serial.println( "%" ); lcd.setCursor(10, 0); lcd.print(" "); lcd.setCursor(10, 0); lcd.print(temperature, 1); lcd.print("C"); lcd.setCursor(10, 1); lcd.print(" "); lcd.setCursor(10, 1); lcd.print(humidity, 1); lcd.print("%"); } }