1 measuring position, 2 measuring pressure – Interlink Electronics FSLP Sensor User Manual
Page 12
www.interlinkelectronics.com
10
Force Sensing Linear Potentiometer (FSLP)
Integration Guide
5.1 Measuring Position
Step 1: Clear Charge on Sensor
Enable all lines as outputs and set them to 0 Volts. This will clear all charge from the
sensor and help reduce noise on readings.
Step 2: Set Up Appropriate Driveline Voltages
Configure sensor terminal 2 as output high (+Vcc).
Configure sensor terminal 3 as output low.
Configure the pin connected to the bottom of resistor R
0
as an output low. This drains
any charge that may have capacitively coupled to the sense line during the
transitions of sensor terminals.
Configure the GPIO pin connected to the bottom of R
0
as a high impedance input.
Configure sensor terminal 1 as an ADC input.
Step 3: Wait For Voltage to Stabilize
The voltage generated on the sense line can have an input resistance ranging from
2kΩ to 300kΩ. Higher resistances result from very light pressure on the sensor.
Depending on the input impedance of the ADC, allowing five to ten microseconds
before taking the measurement will help to increase the sensitivity of the sensor and
detect light touches.
Step 4: Take the measurement
Start the A/D conversion and store the result. An 8-bit ADC will yield a result within 0
and 255 counts. This value is proportional to the physical distance from sensor
terminal 3.
5.2 Measuring
Pressure
Step 1: Setup the appropriate drive line voltages
Configure sensor terminal 2 as an output high (+Vcc).
Configure sensor terminal 1 as an ADC.
Configure sensor terminal 3 as an ADC.
Configure the pin connected to the bottom of R
0
as an output low.
Step 2: Wait for voltage to stabilize
The voltage generated on the sense line can have an input resistance ranging from
2kΩ to 300kΩ. Higher resistances result from very light pressure on the sensor.
Depending on the input impedance of the ADC, allowing five to ten microseconds
before taking the measurement will help to increase the sensitivity of the sensor and
detect light touches.