# How to convert fsr reading into force

I am connecting a flexiforce FSR A201 using a voltage divider into A0 pin. The reading is to be converted into force reading. how to do it?

Force Sensing Resistor (fsr) will give you the values in force readings

@vimaljerome13 No, FSR changes resistance depending on the force applied. Thus, the output is a voltage change. So, I need help to convert the voltage reading into force in Newtons.

Hi,

Please go through the following tutorial on how to interface an FSR with an Arduino.

The basic concept for connection is the same and you should be able to replicate the same results with the Bolt WiFi module.

@vinayak.joshi I want to get the exact force values and not as medium , high or low force classification .

Hi,

Have you read through the link that I supplied in the earlier message?
The post has given calculations on how to select a resistor to be put in series with the FSR to give the right kind of data.

Here you will have to select a resistor such that the full scale reading of the FSR should give a voltage output of 1v.

Once this is done, you can use the add and mul functions on the Bolt Cloud to scale the voltage output from the sensor to the required data.

The Bolt Cloud logs the voltage data as 0 for 0v and 1024 for 1v. So any voltage in between would be scaled accordingly.

@vinayak.joshi Yes, I read it; but I require force readings and not voltage readings.

I told you how to convert the analog readings to voltage readings. The blog gives you a formula for voltage reading to resistance. You can use this in reverse to calculate the resistance of the FSR.

And then finally from the datasheet of FSR A21 you can get the relationship between resistance and applied force.

You will have to reduce these to a relationship between the measured analog value and the force applied.

You can then implement the formula using mul and add functions in the Bolt Cloud.