Measuring Temperature in Embedded Devices
Measuring temperature is easy with an embedded device. There are basically two types of temperature sensors- active and passive. Thermistors, thermocouples, resistive temperature resistors are some popular varieties. The function of these temperature sensors is to provide feedback to the system controller so that it can make decisions such as shutdown, temperature compensation, temperature monitoring, turn on/off of cooling fan and so on.
You may have already seen one type of embedded sensor called thermostat, which is used to measure and control temperature. These are present in ovens, home (and office) heating systems, air conditioners and refrigerators. Thermal sensors are also present on circuit boards, in industrial controls, in data centers and calibration labs.
The perfect temperature sensor will not affect the medium that it is supposed to measure. It should also measure the temperature change accurately and it should respond in an instant. Finally, the signal condition should be good. Of these, the biggest concern is to ensure that the measuring device does not influence the media it is supposed to measure. The embedded designer can improve this by selecting the sensor size carefully and ensuring proper lead configuration and encapsulation. This will reduce measurement errors. He/she should also remember that the smaller the sensor, faster the response.