
with any such calibration scheme, field replacement of parts means that the field
engineer either must be able to calibrate the system, or the calibration values
(microprocessor and/or memory) must be changed if the part of the system
containing the reference is changed.
Microcontroller-based designs often do not have any leftover pins to tell the
CPU when to operate normally and when to capture a calibration value. If your
design uses a pin as an output, you can pull it up with a resistor and use a switch
or shunt jumper to ground it. On power-up, the software checks the pin. If the
pin is high, it is programmed as an output and the normal code is ...