Book Analog Interfacing to Embedded Microprocessors
By measuring the output at several temperatures, you can
build up a table of information that relates the output of that specific sensor to
temperature. This information can be stored in memory. When the micro-
processor reads the sensor, it looks in the memory (or does a calculation) to
determine the actual temperature.
You would want to look at storing this calibration with the sensor if it is not
physically located with the microprocessor. This way, the sensor can be
changed without recalibrating. Figure 1.1 shows three means of handling this
calibration.
In diagram A, a microprocessor connects to a remote sensor via a cable.
The microprocessor stores the calibration information in its EEPROM or flash
memory. The tradeoffs for this method are:
• Once the system is calibrated, the sensor has to stay with that micro-
processor board. If either the sensor or the microprocessor is changed, the
system has to be recalibrated.
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