The Physical world
Temperature is measured in the analog world in Celsius
Sensing the temperature
A Temperature Sensor produces an output voltage relative to the temperature (Celsius).
Converting to a digital value
This stage involved the world of conversion (analog to digital) and is undertaken by an Analog-to-digital converter (ADC). It takes the voltage output from the sensor and converts it to a digital value
Calculating the temperature
With the digital value from the ADC the microcontroller can calculate the temperature.