The LEDs are connected to digital pin 2 to 7. We also define the variable fsrReading which holds the raw analog reading from the FSR. // the FSR and 10K pulldown are connected to a0, // the analog reading from the FSR resistor divider, // the analog reading converted to voltage, // Finally, the resistance converted to force, // We'll send debugging information via the Serial monitor, // analog voltage reading ranges from about 0 to 1023 which maps to 0V to 5V (= 5000mV), // The voltage = Vcc * R / (R + FSR) where R = 10K and Vcc = 5V. You can use this program to control all kinds of other functions, in this case to switch on and off an LED. Hey guys I am fooling around with a force sensitive resistor(FSR) as a button for my project. We will be using a breadboard and jumper wires, as this is the easiest way to prototype a circuit. the code I am wanting to run does an analogRead of the FSR and turns pumps on. In loop function, we take the analog reading from the FSR resistor divider and display it on serial monitor. You should see the following output in the serial monitor: Make sure the serial monitor is also set to a baudrate of 9600. Arduino Prototyping Inputs #31: Force Sensitive Resistor (FSR) - YouTube Force sensitive resistors (FSR) are a simple sensor that makes adding user input easy. Square FSRs are good for broad-area sensing, while small circular sensors can provide greater accuracy to the sensing field. When you push on the sensor, the ink shorts the two traces together with a resistance that depends on the pressure. The easiest way to read the FSR is to connect the FSR with a fixed value resistor (usually 10kΩ) to create a voltage divider. Copyright © 2020 LastMinuteEngineers.com. Note that an FSR is non-polarized, just like normal resistors. When no pressure is being applied to the FSR, its resistance will be larger than 1MΩ. This means that a really light press won’t be detected. As you can see there is a huge drop in resistance when a small amount of pressure is applied. The more pressure you apply, the lower the resistance. For example, with 5V supply and 10K pull-down resistor, when there is no pressure, the FSR resistance is very high (around 10MΩ). In order to measure the applied force with an Arduino, you will need to build a voltage divider circuit with the FSR and a pull-down resistor. The DIY device uses a shunt resistor, a voltage divider, and an LM358 op-amp to produce a voltage that corresponds to the current value. Your email address will not be published. Note that comments are held for moderation to prevent spam. This means that you can connect them either way and they will work fine. So you should see a value between 0 and 1023 in the serial monitor, depending on how hard you squeeze the sensor. // so FSR = ((Vcc - V) * R) / V yay math! I am running into phantom presses though. So you should see a value between 0 and 1023 in the serial monitor, depending on how hard you squeeze the sensor. Force Sensing Resistors are also known as Force Sensitive Resistors or Force Sensors or just FSRs. In this Instructable, I'll show you how to Interface an FSR to Arduino and change the brightness of an LED depending on the pressure applied on the FSR. Pages: [1] Topic: Force Sensing Resistor 100-120 lbs (Read 1 time) previous topic - next topic. The easiest way to measure a resistive sensor is to connect one end to Power and the other to a pull-down resistor to ground. Because the output voltage of the FSR is non-linear I set up a custom range for each LED to turn on. When there is no pressure, the sensor looks like an infinite resistor (open circuit). This sensor is a variable resistor just like a photocell or flex sensor. This circuit creates a variable voltage output that can be read by the ADC (analog to digital converter) input of the microcontroller. This can be pretty useful for calibrating what forces you think the FSR will experience. Wiring Force Sensing Resistor (FSR) to Arduino UNO. The most common types of FSR that you will easily find are the Interlink FSR-402 and FSR-406. The Force Sensing Linear Potentiometer (FSLP) Sensor is Interlink's solution for capturing position and force simultaneously in compact applications. This sketch will read out the sensor data from the analog input of the Arduino and display the output in the serial monitor. The sketch begins with the declaration of the Arduino pin to which FSR and 10K pull-down are connected. For more information, you can check out the datasheet here. The wiring diagram below shows you how to connect the FSR sensor to the Arduino. This are the specifications of the round 402 sensor that I used in this tutorial. 200 kΩ should enable you to see most of the range. That's because the voltage equasion is: Vo = Vcc ( R / (R + FSR) ) That is, the voltage is proportional to the inverse of the FSR resistance. This tutorial explores force sensing resistors (FSRs) with Arduino and how to test and calibrate them. The graph below displays the resistance vs force curve for the FSR 402 sensor. I have included 3 examples with a wiring diagram and code so you can start experimenting with your sensor. As mentioned earlier, the output voltage of the sensor will be between 0 V (no pressure applied) and roughly 5 V (maximum pressure applied). They are low-cost and easy-to-use sensors specifically designed to detect physical pressure, squeeze, and weight. This sensor is a variable resistor just like a photocell or flex sensor. Have it act as a button for switching devices on or off. Kraftempfindlicher Widerstand Dünnfilm Drucksensor MD30-60 0~30KG Durchmesser 30mm Force Sensing Resistor ULTRA THIN FORCE SENSOR ERHÄLT FLEXIBLE UND HOCHGESCHWINDIGKEITSANTWORT - Der flexible Sensor hat die Eigenschaften eines flexiblen, ultradünnen, extrem schnellen Ansprechens usw Force Sensing Resistors are also known as Force Sensitive Resistors or Force Sensors or just FSRs. Most FSRs can sense force in the range of 100 g to 10 kg. It is NOT recommended to solder directly to the exposed silver traces of the sensor. The resistance … To do this you connect one end of the FSR to Power and the other to a pull-down resistor. Then your resistor should be connected between GND and A0. One of the membranes contains two traces running from the tail to the sensing area (the round part). You will find them in electronic drums, mobile phones, handheld gaming devices and many more portable electronics. /* Simple example code for Force Sensitive Resistor (FSR) with Arduino. This example also debounces the input and is based on the Arduino Switch tutorial. The technology used in FSRs is patented by Interlink Electronics which has been in operation since 1985. // fsrVoltage is in millivolts so 5V = 5000mV, // Use the two FSR guide graphs to approximate the force, Arduino Code – Simple Analog FSR Measurements, Arduino Code – Advanced Analog FSR Measurements. How to use a SHARP GP2Y0A21YK0F IR Distance Sensor with Arduino, How to use a SHARP GP2Y0A710K0F IR Distance Sensor with Arduino, How to use an HC-SR04 Ultrasonic Distance Sensor, LM35 analog temperature sensor with Arduino tutorial, TMP36 analog temperature sensor with Arduino tutorial, Arduino Nano Board Guide (Pinout, Specifications, Comparison), The complete guide for DS18B20 digital temperature sensors with Arduino, How to use an IR receiver and remote with Arduino, Project #2: Pressure Sensor Switch Cat Helmet – Art 150: Intro to New Media, https://www.makerguides.com/fsr-arduino-tutorial/, How to control a character I2C LCD with Arduino, TM1637 4-digit 7-segment LED display Arduino tutorial. As mentioned earlier, the output voltage of the sensor is between 0V (no pressure applied) and approximately 5V (maximum pressure applied). When the Arduino converts this analog voltage into digital, it actually converts it to a 10-bit number of range 0 to 1023. The resistance range is actually quite large: > 10 MΩ (no pressure) to ~ 200 Ω (max pressure). There is no positive or negative side, just connect them in the orientation you want. Uses less than 1mA of current, depending on the resistor used in the voltage divider. If everything is fine, you should see below output on serial monitor. How to measure force/pressure with an FSR As we've said, the FSR's resistance changes as more pressure is applied. For most projects, this is pretty much all that’s needed. This table indicates the approximate analog voltage based on the sensor force/resistance w/a 5V supply and 10K pulldown resistor. They are pretty much used in DIY electronics as they are available at low cost. It measures the approximate Newton force measured by the FSR. Filed Under: Arduino, TutorialsTagged With: Arduino, Force Sensing Resistor, Force Sensitive Resistor, FSR, LED, Pressure, Sensor, Touch, Tutorial, […] Link to code source: https://www.makerguides.com/fsr-arduino-tutorial/ […], Your email address will not be published. An FSR consists of two membranes and a spacer adhesive. Note that the data is plotted on logarithmic scales. This results in the following output voltage: As you can see, the output voltage varies from 0 to 5V depending on the amount of force applied to the sensor. The graph below displays approximately the resistance of the sensor at different force measurements for the FSR 402 sensor. Mar 02, 2014, 05:21 pm. I hope you found it useful and informative. We will use 5 volts of power from the 5V terminal of the arduino. In this tutorial you will learn how to use an FSR - Force Sensitive Resistor with Arduino to fade an LED. Put your sensor in resistance (Ω) measuring mode and you should see the resistance value change when you press on the sensor. The lower the force rating, the more sensitive the FSR is. You will find them in electronic drums, mobile phones, handheld gaming devices and many more portable electronics. Connect one of the leads of the FSR to power (5 V, but 3.3 V works just fine too) and the other lead to the analog in of the Arduino (A0). You need to connect a 10kΩ pull-down resistor in series with the FSR to create a voltage divider circuit. Now that you know the sensor is working correctly, it is time to connect it to the Arduino. If you need a more permanent solution, I highly recommend the Amphenol FCI Clincher Connector. For this purpose, Utsav Shah decided to create his own current sensor capable of handling up to 15A.. Here’s how the output looks like in the serial monitor. Another key feature of the FSR is its rated sensing range, which defines the minimum and maximum pressures that the sensor can differentiate between. The most common types of FSR that you will find are the Interlink FSR 402 and 406. eval(ez_write_tag([[300,250],'makerguides_com-large-mobile-banner-2','ezslot_11',142,'0','0']));The sketch below will toggle the LED on and off when you press on the FSR. I have not written the code for that yet as when I am just doing a general test of the FSR with an LED, I am getting phantom presses. A force-sensing resistor is a material whose resistance changes when a force, pressure or mechanical stress is applied. The 10 kΩ pulldown resistor gets connected between GND and A0. All rights reserved. It just prints out what it interprets as the amount of pressure in a qualitative manner. This means that it will map the input voltage between 0 and 5 V into integer values between 0 and 1023. While these sensors are great for measuring pressure, they are not great at finding how many pounds of weight they have on them. The other membrane is coated with a conducting ink. Next, we will look at using this sensor as a toggle switch. Most FSRs have either a circular or rectangular sensing area. For example, a smaller 1kg rated FSR may provide more sensitive readings from 0 to 1kg, but cannot tell the difference between 2kg and 5kg weight. The resistance changes by applying pressure on it. The negative lead of the LED (the short lead) gets connected to GND via a resistor and the positive lead to digital pin 2. You might need to tweak this slightly for your own sensor. However, if you just want to find out “whether the sensor has been squeezed or pressed and how much” they are a good option for your next touch-sensing project. The output of the voltage divider configuration is described by the equation: In the shown configuration, the output voltage increases with increasing force. The example below makes it easy to see how much pressure you apply to the FSR. The sensor's tough, moisture resistant surface can be used with a finger, stylus, or glove; even in harsh environments. Our next arduino sketch is pretty advanced. So you will see a value between 0 and 1023 in a serial monitor, depending on how hard you squeeze the sensor. Now that you have wired up the sensor, you can upload the following example code using the Arduino IDE. When no force is applied, the FSR resistance will be really high, take 10 MΩ as an example. > Using Arduino > Sensors > Force Sensing Resistor 100-120 lbs; Print. For example, you can use them to play a tune each time to tap the sensor. Note that the output voltage you measure is the voltage drop across the pull-down resistor, not across the FSR. Notice that the graph is generally linear from 50g and up, but not below 50g. The harder you press on the head of the sensor, the lower the resistance between the two terminals will be, but as you remove the pressure it will return to its original value. This means that whenever we put pressure on it, its resistance quickly decreases from infinity to 100K, and then becomes more linear. The technology used in FSRs has been patented by Interlink Electronics which has been in operation since 1985. If you have any questions, suggestions, or if you think that things are missing in this tutorial, please leave a comment down below. Below table indicates the approximate analog voltage based on the sensor force/resistance with 5V supply and 10K pulldown resistor. The FSR is also connected in the same way as before. If you did, please share it with a friend that also likes electronics! If you would like to learn about other sensor, check out the articles below: Makerguides.com is a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for sites to earn advertising fees by advertising and linking to products on Amazon.com. At around 10 kg (not shown in the graph) the sensor is saturated and an increase in force yields little to no decrease in resistance. The more it is pressed, the more resistive carbon elements touch the conductive traces and this reduces resistance. In this article, I have shown you how an FSR works and how you can use it with Arduino. Then the point between the pull-down resistor and the FSR is connected to the A0 ADC input of an Arduino. The calibration method is based on the force of gravitation and uses calibrated masses, along with a 3D printed plate that allows consistent force impact over the calibration process. There are plenty of uses of a force sensing resistor in Arduino projects. A 10 kΩ resistor works well if you want to use the sensor over its entire force range (100 g to 10 kg). Below is just a few examples of what you can do. It can be bought in a circular form or square form. As we have said, FSR is basically a resistor that changes its resistive value depending on how much it has been pressed. Hi I'm looking for the FSR (Force Sensing Resistor) that they can work with a range of 100-120 lbs (444-520 N). Note that the data is plotted on logarithmic scales. The response is not linear! Go Down. Below you can find all the CAD files for sensors of the interlink 400 Series. When working with electronics, voltage is fairly easy to measure, but current often takes a bit more finesse. You can use the following values as a guide: If you don’t have any of these resistor values, try to find one that is close. Interfacing Force Sensing Resistor (FSR) with Arduino. First I will show you the basic operation of the sensor. There are a variety of FSR options out there, and a few key features such as size, shape, and sensing range that set them apart. Selecting the right size resistor to match your sensor can be a bit tricky and depends on the force range you want to measure. A great selection can be found at digikey at the following link: Digikey- Force sensing resistors. The harder you press on the sensor’s head, the lower the resistance between the two terminals drops. Note that the output voltage you measure is the voltage drop across the pull-down resistor, not across the FSR. Any! More info: https://www.makerguides.com */ // Define FSR pin: #define fsrpin A0 //Define variable to store sensor … Required fields are marked *, © 2020 Makerguides.com - All Rights Reserved. Any pressure beyond the sensor’s maximum range is unmeasurable (which can also damage the sensor). When there is no pressure, the sensor looks like an infinite resistor (open circuit), as the pressure increases, the resistance goes down. The resistance of an FSR varies as the force on the sensor increases or decreases. Connect one of the leads of the FSR to power and the other lead to the analog in of the Arduino (A0). FSRs are super robust pressure sensors that are used in all kinds of industries. For our first experiment, we will read the sensor data from the ADC pin of the Arduino and display the output on the serial monitor. The more pressure you apply, the more LEDs will turn on. They are also known as "force-sensitive … If you don’t have one of those, just play around with the range settings. Lastly, I will show you how you can use LEDs to show the amount of pressure applied to the sensor. fadami80 Guest; Force Sensing Resistor 100-120 lbs. The value of the resistor depends on the color LED you are using. As mentioned in the introduction, you need to create a circuit with a 10 kΩ pulldown resistor. The resistance of an FSR depends on the pressure that is applied to the sensing area. The easiest way to see if your FSR is working correctly is to connect it to a multimeter. The easiest way to connect to an FSR is to use a breadboard. Interlink suggests a minimum bending radius of 2.5 mm. The code is pretty straightforward. This works great for prototyping and testing. This results in the following output voltage: If you press really hard on the FSR, the resistance will go down to roughly 250 Ω. In this tutorial you will learn how an FSR works and how to use it with Arduino. Then the point between the fixed value pull-down resistor and the variable FSR resistor is connected to the ADC input of an Arduino. The substrate will melt during soldering and the solder joint won’t hold. It is made up of several thin flexible layers. The conducting membranes are separated by a thin air gap when no pressure is applied. It also includes data for the other sensors of the 400 Series. In this example you will be using the FSR sensor as a toggle switch. I used a 10 kΩ pull-down resistor and a Vcc of 5 V for this tutorial, which results in the following output when no force is applied: Vout = 5 V x 10 kΩ/ (10 kΩ + 10 MΩ) = 0.005 V. So almost 0 V. If you press really hard on the FSR, the resistance will go down to roughly 200 Ω. The Flexiforce sensor and the 10k resistor makes a voltage divider, this way for different forces or pressure values we will get different voltages. Note that our method takes the somewhat linear resistivity but does not provide linear voltage! To connect your Arduino UNO to your FSR, simply use your breadboard and jumper wires. I used alligator test leads to connect the multimeter to the exposed leads of the sensor. 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