Last time we covered using watchdog timer as temperature dependent component of a microcontroller to do temperature sensing. Now lets take a diode to do the same thing, they are pretty much accurate and cheap, see Cypress’ application note about its implementation.
There are various sensors available for measuring temperature such as Thermistor, Thermocouple, resistance temperature detectors (RTD). Choosing a sensor or method to employ for measuring the temperature depends on factors such as the accuracy requirement, the temperature range to be measured, and the cost of the temperature sensor. The diode based temperature measurement is an easy, accurate, and also relatively low-cost method for measuring the temperature.