Book Analog Interfacing to Embedded Microprocessors
than other methods. In addition, if the calibration is performed by calcula-
tion instead of by table lookup, all sensors that are the same can use the same
software routines, each sensor just having different calibration constants.
Diagram B shows an alternate method of handling a remote sensor, where
the EEPROM that contains the calibration data is located on the board with
the sensor. This EEPROM could be a small IC that is accessed with an I2C or
microwire interface (more about those in Chapter 2, “Digital-to-Analog
Conversion”). The tradeoffs here are:
• Since each sensor carries its own calibration information, sensors and
microprocessor boards can be interchanged at will without affecting results.
Spare sensors can be calibrated and stocked without having to be matched
to a specific system.
• More memories are required, one for each sensor that needs calibration.
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