In this project you will learn to interfacing LM35 temperature sensors with Atmega8 or Atmega16 using LCD or Seven Segment Leds. Atmega 8 and Atmega 16 are the highly advanced and versatile microcontrollers from ATMEL’s AVR family. Atmega16 is based on a 40 pin count microcontroller based on RSIC with 131 powerful hardware instructions. It is integrated with 16 KB flash memory with static 1KB RAM and 512 Bytes of EEPROM. It has a maximum 16 MHz clock frequency.
AVRs have 8 bit CMOS architecture based on RSIC. Only one clock cycle is used to execute a single instruction. It has 32 input output ports to communicate with the outer world. Inbuilt serial UART, timer, interrupt, ADC, PWM. It has In System Programmable flash memory, you don’t need to remove chips from the hardware.
About LM35 Temperature Sensor
It has a 3 pin device sensor which is capable of measuring temperature range from -55 C to 150 C. Output pin is connected with Atmega8 or Atmega16 ADC pin. MCU accepts the output and converts it into digital format. Important role is performed by ADC of Atmega microcontroller. For more information and extensive study of ADC of AVR, read the datasheet of ATmega16/ATmega32. LM35 is an electronic device used to convert temperature into digital form of voltage.
Characteristics of the LM35
1. Temperature sensitivity is between the voltage and temperature of 10 mV/0C.
2. Accuracy level is 0.50C at a temperature 50C.
4. Operational voltage is from 4-13 volts.
5. Low current of less than 60 mA.
6. Less Self heating.
Example in this project you will learn how to interface LM35 Temperature sensor using LCD 16×2 hd44780 with Atmeg8 or Atmega16 microcontroller, and you can download source code from here. 2 line LCD is given to display the surrounding temperature when we connect LM35 with Analog to Digital pin ADC of the Atmega8 Microcontrollers, this pin is responsible to convert electrical signals into digital format so that microcontroller can read it. You can replace any Atmel microcontroller Atmega family with any chip either Atmega8, 16, 32, you can use seven segment LEDs also but here we will discuss about 16×2 LCD display.
Interfacing Diagram Circuit LM35 + Atmega 8/16 + LCD Display 16×2 HD44780
Circuit presented here shows clearly, first two pins of LM35 are connected with power supply to 5volts and Gnd. Now the output pin of LM35 is directly connected with any ADC of Atmega8/16. We need a development board to develop this project which includes LCD which is connected with through microcontroller pins to display the temperature.
LCD (Liquid Crystal Display 16×2 HD44780)A display unit used to show and flash messages in the form of graphics, texts, numbers and alphanumeric characters, LCD integrated with microcontroller with its ports and and other control bits to display the messages of its own choice. Normally to show temperatures, date and time, and other status.