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.
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.
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.
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.
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.
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.
Comments
Please log in or sign up to comment.