How Does It Work?





The DHT22 sensor can measure the temperature and humidity. We will read the temperature and humidity values from the DHT22 sensor and then we will calculate the heat index using these values.

Then we will send these values to the SD card using the library functions. First, we will check to see if the SD card has initialized properly or not. If the SD card has not initialized properly, then we need to create a file in the SD card in which we will send the data. Then we will write the sensor readings one by one in the SD card file.

The file name you are going to use for the SD card file should be in the 8.3 format. An example of a file name using the 8.3 format is “file1234.txt”. File names longer than that will create an error. If you are using the SD card for the first time, then it is recommended to format it before using it.

Circuit Diagram





First of all, place the Ethernet shield on the Arduino and insert the SD card in the SD card slot on the Arduino. Then make the connections for the DHT22 sensor with the Arduino as follows: