In this project, we will use the Arduino development board to make a temperature data logger. The device obtains the temperature value from the temperature sensor LM35 and the time from the DS3231 real-time clock module. Then we will use the mini SD card module to store these values in an SD card file. After that, we access the file from the PC and create a chart of these values in Microsoft Excel.

Required components

The components required for this project are as follows

  • Arduino Uno development board
  • DS3231 real-time clock module
  • Mini SD card module
  • LM35 temperature sensor
  • Connecting wires
  • Breadboard

Circuit schematic

The connection method of Arduino development board and DS3231 clock module is as follows

  • Connect the GND of DS3231 to the GND of Arduino
  • Connect the VCC of DS3231 to the 5V pin of Arduino
  • Connect SDA of DS3231 to A4 on Arduino
  • Connect SCL of DS3231 to A5 of Arduino

The connection method of Arduino development board and SD card module is as follows

  • Connect CS of mini SD card module to digital pin 10 of Arduino
  • Connect the SCK of the mini SD card module to the digital pin 13 of the Arduino
  • MOSI of mini SD card module is connected to digital pin 11 of Arduino
  • Connect the MISO of the mini SD card module to the digital pin 12 of Arduino
  • Connect the VCC of the Mini SD card module to the digital 5V of the Arduino
  • Connect the GND of the Mini SD card module to the digital GND of the Arduino

The connection method of Arduino development board and LM35 temperature sensor is as follows

  • The VCC pin of LM35 is connected to the 5V pin of Arduino
  • The OUT pin of LM35 is connected to A0 of Arduino
  • The GND pin of LM35 is connected to the GND of Arduino

Working principle

The LM35 temperature sensor outputs signals in an analog way. We need to use ADC to convert this output in order to be able to measure temperature. The Arduino development board has a built-in ADC, through which the output of LM35 can be converted into a temperature value.

The DS3231 clock module is connected to the Arduino through I2C communication. Therefore, we only need to connect the SCL and SDA pins on the DS3213 to the Arduino, and the module will begin to communicate. The module has a separate battery, which allows it to operate normally even if it is not powered by Arduino.

Then use the SD card module to store the temperature and time in the SD card. The SD card module will open the SD card and store data in it. After that, we open the file on the PC and use these values in Microsoft Excel to generate a chart.