Temperature controller uses TMP37 temperature sensor from Analog Devices. As PIC 16F84 doesn’t have any analogue inputs there is an external ADC TLC549 used which converts temperature sensor readings in to serially transmitted digital data.

Temperature controller is also interfaced with four buttons( for setting parameters like alarm, set point) and LCD display where current temperature is displayed. Project is very well explained, with lots of helpful links that explain all the basics including understanding and flashing PIC microcontrollers.