5.1 Force Sensing Resistor (FSR) Interface Using PIC16F17146 Microconctroller

The Force Sensing Resistor (FSR) is a Polymer Thick Film (PTF) device which exhibits a decrease in resistance with an increase in the force applied to the active surface. A change in resistance can be measured using a current to voltage converter circuit that uses an OPA, as explained in section Current-to-Voltage Converter . The FSR sensor can be interfaced easily using integrated OPA and ADCC available in the PIC16F17146 family of microcontrollers.

Refer to Figure 5-1 which highlights interfacing FSR sensor with PIC16F17146 family of microcontrollers.

The output voltage (V_OUT) of OPA in the signal conditioning circuit shown in Figure 5-1 is:

$V_{OUT}=V_{DD}/2\times [1+R_G/R_{FSR}]$

OPA: Configured as current to voltage converter and its non-inverting channel is configured to V_DD/2.

ADCC: OPA output is connected internally to ADCC.