4 A SMART SENSOR WITH NON-LINEAR RESPONSE AND AUTOCALIBRATION

In the case of a non-calibrated sensor, or of mechanical drift of the input system, the meanpoint

value may be slightly different from the theoretical reference value and subsequently induce

some unwanted actions on the outputs. One solution is to perform an autozero process

allowing a tolerance window for the meanpoint, as represented on the flowchart in Figure 6: As

long as the initial value at reset is within a tolerance window around the theoretical value of

127, the shift is considered as irrelevant and that initial value is used as the new reference; On

the contrary, any input value out of this tolerance window is understood as an instruction

request to use 127 as the reference value.

Figure 6: Flowchart Of The Autozero Process At Reset

Output = 00

Input Value in

Tolerance Window

Store Input Value

as Reference

Store Default Value

127 as Reference

Output = Input - Reference

No

Yes

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