Interlink Electronics FSLP Sensor User Manual

Page 13

www.interlinkelectronics.com

Force Sensing Linear Potentiometer (FSLP)

Integration Guide

Step 3: Take two measurements

 Take an ADC reading on the ADC connected to sensor terminal 3. Call this V1.
 Take an ADC reading on the ADC connected to senor terminal 1. Call this V2.

Step 4: Calculate the pressure

 We know the values of V2 and R

. Therefore, the current through R

can be

calculated as

 The current I, is the same current that flows through Rp.
 No current flows through R2; therefore, the voltage drop across Rp is simply V1-V2.
 Rp now be calculated using:

 Because the value of Rp decreases with force, what we really want is the reciprocal

of the expression above:

 R

is a constant; therefore, we can think of it as a scaling factor. The scaling factor

should be a convenient value, typically a power of 2 (e.g. 32 or 64). Choose the value
of the scaling factor on an application-specific basis to yield the best data.

 The final expression is: