When the Arduino converts this analog voltage into digital, it actually converts it to a 10-bit number of range 0 to 1023. You will find them in electronic drums, mobile phones, handheld gaming devices and many more portable electronics. In this tutorial you will learn how to use an FSR - Force Sensitive Resistor with Arduino to fade an LED. Interlink suggests a minimum bending radius of 2.5 mm. The resistance range is actually quite large: > 10 MΩ (no pressure) to ~ 200 Ω (max pressure). When you push on the sensor, the ink shorts the two traces together with a resistance that depends on the pressure. This sensor is a variable resistor just like a photocell or flex sensor. The harder you press on the sensor’s head, the lower the resistance between the two terminals drops. There are plenty of uses of a force sensing resistor in Arduino projects. The output of the voltage divider configuration is described by the equation: In the shown configuration, the output voltage increases with increasing force. As mentioned in the introduction, you need to create a circuit with a 10 kΩ pulldown resistor. 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. In this article, I have shown you how an FSR works and how you can use it with Arduino. Lastly, I will show you how you can use LEDs to show the amount of pressure applied to the sensor. It is quite easy to connect FSR to an arduino. I have included 3 examples with a wiring diagram and code so you can start experimenting with your sensor. The technology used in FSRs has been patented by Interlink Electronics which has been in operation since 1985. It looks at the value of the analog input pin and changes the state of the LED when the value exceeds 500. The technology used in FSRs is patented by Interlink Electronics which has been in operation since 1985. Copyright © 2020 LastMinuteEngineers.com. Then the point between the pull-down resistor and the FSR is connected to the A0 ADC input of an Arduino. 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. An FSR consists of two membranes and a spacer adhesive. 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. As we have said, FSR is basically a resistor that changes its resistive value depending on how much it has been pressed. This means that a really light press won’t be detected. The sensor's tough, moisture resistant surface can be used with a finger, stylus, or glove; even in harsh environments. 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. 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. Next, we will look at using this sensor as a toggle switch. As you can see there is a huge drop in resistance when a small amount of pressure is applied. // 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. The graph above shows the Vout vs Force curves for different values of R (the pull-down resistor). This can be pretty useful for calibrating what forces you think the FSR will experience. Wiring Force Sensing Resistor (FSR) to Arduino UNO. The resistance of an FSR depends on the pressure that is applied to the sensing area. A force-sensing resistor is a material whose resistance changes when a force, pressure or mechanical stress is applied. This table indicates the approximate analog voltage based on the sensor force/resistance w/a 5V supply and 10K pulldown resistor. The wiring diagram below shows you how to connect the FSR sensor to the Arduino. If you need a more permanent solution, I highly recommend the Amphenol FCI Clincher Connector. The graph below displays the resistance vs force curve for the FSR 402 sensor. 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. These traces are woven together, but not touching. 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. Uses less than 1mA of current, depending on the resistor used in the voltage divider. Most FSRs have either a circular or rectangular sensing area. When no force is applied, the FSR resistance will be really high, take 10 MΩ as an example. You should see the following output in the serial monitor: Make sure the serial monitor is also set to a baudrate of 9600. The substrate will melt during soldering and the solder joint won’t hold. First I will show you the basic operation of the sensor. 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 FSRs are basically resistors. 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