Published May 22, 2020 © LGPL

Force Sensing Resistor (FSR) - 10 cm long Tail and Ring

Interlink Electronics manufactures FSRs. Let's take a closer look at that.

IntermediateProtip30 minutes2,843

Things used in this project

Hardware components

Force Sensing Resistor - Ring - 40-24131

Force Sensing Resistor - 10 cm Tail - 34-00034

Force Sensing Resistor - Connector - 14-21542

10 LEDs Bar Array, Green

I my case I use Kingbright DC-10GWA (full green) and Kingbright DC-7G3HWA (3 colors) - as an alternative, you can also use individual LEDs.

Jumper wires (generic)

20 pcs for LED Bar Graph and 3 for Force Sensing Sensor

Breadboard (generic)

Arduino UNO

Hand tools and fabrication machines

Soldering Station, 110 V

to solder the extended legs to the connector

Story

Today we are dealing with 2 Force Sensing Resistors (FSRs) from Interlink Electronics - known among other things for its FSR402.

So far I only knew them with 2 PINs: but these products are already equipped with 4 PINs, of which the PIN printed with the manufacturer's label has so far been of no importance for signal transmission.

So we can confidently focus on VCC, GND and signal.

FSR assignment from left (manufacturer's signet) to right:

PIN1: no assignment
PIN2: GND
PIN3: 5V / 3.3V
PIN4: signal A0

The first hurdle had to be overcome when setting up the circuit: the flat cable ends can be inserted into the manufacturer's own PIN connectors in a dimensionally stable manner and securely fixed. But the 4 outstanding PINs of the connector are not suitable for a breadboard (2.54mm). I always have my soldering iron at the right temperature, so I tinkered with a few extensions. Not nice, but functional.

connctor with extensions

In the second step, we look for the PIN assignment from the data sheet - 10 cm tail and ring are attached to this project in the attachments. If necessary, you can also register with the manufacturer and you will receive updates of the good documentation free of charge via email.

When the measured values at A0 - the ADC of the 10-bit Arduino Uno (= 0-1023) were listed in the serial monitor with the usual sample code "analog read" from the Arduino IDE, I still had an optical output supplemented by 2 LED bar graphs. For this I refer to my own project for the commissioning of LED bar graphs.

10 cm Tail - 34-00034

Just a light breath was enough to change the measured values at the FSR and so I applied force with different pressure strengths of my hand at different positions of the sensor and looked at the results.

playing around

As a result, I came to 2 insights:

a.) I was not only able to set a trigger for very little pressure, for example for my LED bar graph, but

b.) also query the print area and only activate or deactivate parts of the LEDs.

This was achieved with differently defined return values of the sensor, in my opinion almost the same effort. I was then able to query this in an if-clause and respond to it.

This brings us to one of the possible areas of application: These sensors are also intended for the use of menu-based devices in the audio or smartphone sector.

use a finger, stylus or glove

The design of the round FSRs with its optical division of the surface material into 3 parts also indicate this. Conversely, we get 3 (flexible) buttons and only use 1 signal PIN on our device.

I am a big ring

squeeze myself quietly: I am flexible and stand up again

The modern home office swivel chairs are certainly equipped with these sensors to check the readiness of the employees to sit. Fortunately, "standing" also counts to working hours and we can also take a break at this point.

Since you are interested in these sensors, you can place your order here. If you have any questions, Sales is always available to address your concerns.

For your quick tests, I recommend ordering the sensor with female jumper contacts directly. These are available with housing as well as male or female.

Code

const int analogPin = A0; // the pin that the potentiometer is attached to
const int ledCount = 10; // the number of LEDs in the bar graph
int ledPins[] = {2, 3, 4, 5, 6, 9, 10, 11, 12, 13}; // an array of pin numbers to which LEDs are attached


void setup() {
  // initialize serial communication at 9600 bits per second:
  Serial.begin(9600);
     // loop over the pin array and set them all to output:
  for (int thisLed = 0; thisLed < ledCount; thisLed++) {
      pinMode(ledPins[thisLed], OUTPUT);
  }
}

// the loop routine runs over and over again forever:
void loop() {
  // read the input on analog pin 0:
  int sensorValue = analogRead(analogPin);
  // print out the value you read:
  Serial.println(sensorValue);
   
  if (sensorValue <= 380) {
    digitalWrite(ledPins[0], HIGH);
    digitalWrite(ledPins[1], HIGH);
    digitalWrite(ledPins[2], HIGH);
    for (int thisLed = 3; thisLed < ledCount; thisLed++) {
      digitalWrite(ledPins[thisLed], LOW);
    }
    
  } else if (sensorValue > 380 && sensorValue <= 500) {
    digitalWrite(ledPins[3], HIGH);
    digitalWrite(ledPins[4], HIGH);
    digitalWrite(ledPins[5], HIGH);
    for (int thisLed = 6; thisLed < ledCount; thisLed++) {
      digitalWrite(ledPins[thisLed], LOW);
    }
    digitalWrite(ledPins[0], LOW);
    digitalWrite(ledPins[1], LOW);
    digitalWrite(ledPins[2], LOW);

  } else if (sensorValue > 500 && sensorValue <= 530 ) {
    digitalWrite(ledPins[9], HIGH);
    for (int thisLed = 0; thisLed < 9; thisLed++) {
      digitalWrite(ledPins[thisLed], LOW);
    }
      
  } else if (sensorValue > 530 && sensorValue <= 700) {
    digitalWrite(ledPins[6], HIGH);
    digitalWrite(ledPins[7], HIGH);
    digitalWrite(ledPins[8], HIGH);
    for (int thisLed = 0; thisLed < 6; thisLed++) {
      digitalWrite(ledPins[thisLed], LOW);
    }
    for (int thisLed = 9; thisLed < ledCount; thisLed++) {
      digitalWrite(ledPins[thisLed], LOW);
    }
  }
   
}

const int analogPin = A0; // the pin that the potentiometer is attached to
const int ledCount = 10; // the number of LEDs in the bar graph
int ledPins[] = {2, 3, 4, 5, 6, 9, 10, 11, 12, 13}; // an array of pin numbers to which LEDs are attached

void setup() {
  // initialize serial communication at 9600 bits per second:
  Serial.begin(9600);
     // loop over the pin array and set them all to output:
   for (int thisLed = 0; thisLed < ledCount; thisLed++) {
      pinMode(ledPins[thisLed], OUTPUT);
   }
}

void loop() {
  // read the input on analog pin 0:
  int sensorValue = analogRead(analogPin);
  // print out the value you read:
  Serial.println(sensorValue);
   
  if (sensorValue <= 75) {
    digitalWrite(ledPins[0], HIGH);
    digitalWrite(ledPins[1], HIGH);
    for (int thisLed = 2; thisLed < ledCount; thisLed++) {
      digitalWrite(ledPins[thisLed], LOW);
    }
    
  } else if (sensorValue > 75 && sensorValue <= 95) {
    digitalWrite(ledPins[2], HIGH);
    digitalWrite(ledPins[3], HIGH);
    for (int thisLed = 4; thisLed < ledCount; thisLed++) {
      digitalWrite(ledPins[thisLed], LOW);
    }
    digitalWrite(ledPins[0], LOW);
    digitalWrite(ledPins[1], LOW);
    
  } else if (sensorValue > 95 && sensorValue <= 135) {
    digitalWrite(ledPins[4], HIGH);
    digitalWrite(ledPins[5], HIGH);
    for (int thisLed = 0; thisLed < 4; thisLed++) {
      digitalWrite(ledPins[thisLed], LOW);
    }
    for (int thisLed = 6; thisLed < ledCount; thisLed++) {
      digitalWrite(ledPins[thisLed], LOW);
    }
    
  } else if (sensorValue > 135 && sensorValue <= 350) {
    digitalWrite(ledPins[6], HIGH);
    digitalWrite(ledPins[7], HIGH);
    for (int thisLed = 0; thisLed < 6; thisLed++) {
      digitalWrite(ledPins[thisLed], LOW);
    }
    
  } else if (sensorValue > 350 && sensorValue <= 500) {
    digitalWrite(ledPins[8], HIGH);
    digitalWrite(ledPins[9], HIGH);
    for (int thisLed = 0; thisLed < 8; thisLed++) {
      digitalWrite(ledPins[thisLed], LOW);
  }
  
  } else if (sensorValue > 500 && sensorValue <= 1023) {
    for (int thisLed = 0; thisLed < ledCount; thisLed++) {
      digitalWrite(ledPins[thisLed], LOW);
    }
  }
  
}

Credits

Ingo Lohs

182 projects • 198 followers

I am well over 50 years and come from the middle of Germany.

Contact

Thanks to Jaynie Lajoy.

Comments

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Force Sensing Resistor (FSR) - 10 cm long Tail and Ring

Things used in this project

Hardware components

Hand tools and fabrication machines

Story

Schematics

Datasheet Force Sensing Resistor

Datasheet Force Sensing Resistor - Ring

Code

Analog Read Example code from Arduino IDE - LED Bar Graph triggered by FSR Ring

Analog Read Example code from Arduino IDE - LED Bar Graph triggered by FSR Tail 10cm

Credits

Ingo Lohs

Comments

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Force Sensing Resistor (FSR) - 10 cm long Tail and Ring

Force Sensing Resistor (FSR) - 10 cm long Tail and Ring

Things used in this project

Hardware components

Hand tools and fabrication machines

Story

Schematics

Datasheet Force Sensing Resistor

Datasheet Force Sensing Resistor - Ring

Code

Analog Read Example code from Arduino IDE - LED Bar Graph triggered by FSR Ring

Analog Read Example code from Arduino IDE - LED Bar Graph triggered by FSR Tail 10cm

Credits

Ingo Lohs

Comments

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