Abstract
This project is a standalone digital temperature meter that also controls the temperature of the heating element of a device according to its requirement. Use of embedded technology makes this closed loop feedback control system efficient and reliable. Microcontroller (AT89S52) allows dynamic and faster control. Push button switches and liquid crystal display (LCD) make the system user-friendly.
The sensed and set temperature values are simultaneously displayed on the LCD panel. The circuit is programmed for on/ off control. It is very compact using few components and can be implemented for several applications including air-conditioners, water-heaters, snow-melters, ovens, heat-exchangers, mixers, furnaces, incubators, thermal baths and veterinary operating tables. AT89S52 micro controller is the heart of the circuit as it controls all the functions.
The temperature sensor LM35 senses the temperature and converts it into an electrical signal, which is applied to the micro controller through ADC. The analog signal is converted into digital format by the analog-to-digital converter (ADC). The sensed and set values of the temperature are displayed on the 16x2-line LCD. The set temperature value can be varied from 1C to 255C using an external PCB mount push on switch. Since the microcontroller cannot drive the boilers or any devices which requires 230v AC supply, TRIAC is used to drive these elements.
SOFTWARE AND HARDWARE TOOLS:
Software Tools:
- Keil compiler
- Orcad.
Hardware Tools:
- Microcontroller AT89S52.
- Thermistor
- Buzzer
- ADC
- LCD
- LED array
- TRIAC and TRIAC diver
- Switches
Block Diagram
