Design and implementation of a digital thermometer with clock

Abstract

In this paper, the design of a digital thermometer with clock is presented. The design was achieved using ATMEGA 328P PU Microcontroller Unit, MLX90614 Infrared Sensor for achieving contactless measurement (wireless) and the DS1307 Real Time Clock (RTC) for accurate time keeping during the measurement of this parameter.The MLX90614 is factory calibrated in wide temperature ranges from - 40 ºC to 125ºC for the ambient temperature and -70 ºC to 382.19ºC for object temperature, while the DS1307 is a low-power clock/calendar with 56 bytes of battery-backed serial random access memory (SRAM). Power is supplied using a regulated 9 V DC battery. The microcontrollers and RTC chip are powered by 5 V DC. The temperature sensor and liquid crystal display (LCD) require 3.3 V DC for operation and are supplied by passing the 5 V DC through a variable resistor. The sensors output values are both fed into the microcontroller. While monitoring temperature and telling time, the microcontroller sends the measurements in form of digital signal to the LCDs for display.This design was compared with a standard infrared thermometer by taking the body temperature measurements of two individuals at different times of the day. It was observed from the results that the difference between the temperature readings of the two thermometers ranges from 0 to 1 °C

Keywords: Infrared sensor, digital thermometer, microcontroller, real time clock, temperature