To convert the ADC value to a voltage value, you can use the following equation:
Voltage = (ADC value / (2^n - 1)) * (Vref)
ADC value is the digital value output by the ADC
n is the number of bits in the ADC (8-bits in your example)
Vref is the reference voltage for the ADC (usually 3.3V or 5V)
So, for an 8-bit ADC with a reference voltage of 5V, the voltage value corresponding to an ADC value of 255 (the maximum value) would be:
Voltage = (255 / (2^8 - 1)) * 5V = 5V
And the voltage value corresponding to an ADC value of 0 (the minimum value) would be:
Voltage = (0 / (2^8 - 1)) * 5V = 0V
Once you have the voltage value, you can convert it to temperature using a thermistor, a thermocouple, or any other type of temperature sensor. This conversion typically involves using a mathematical equation or a lookup table based on the characteristics of the temperature sensor.
Remember that the voltage-to-temperature conversion is not linear, and the sensor may have a different temperature coefficient. That's why the manufacturer will provide a lookup table or a mathematical equation that relates the sensor's voltage output to temperature.