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Topic: Weight Sensor? (Read 112 times) previous topic - next topic

StutteringJack

I'm making a project with a coaster combined with some LED neopixels and a sensor, the way it works is that when I set down my cup on the coaster, the LED's flash on, do whatever they want, until I take my cup off the coaster. I need a weight sensor or a pressure sensor that is flat, in between 2" to 3.5" squared, and there will be roughly a quarter of a pound on the sensor to begin with, and needs to be able to sense if anything greater than a quarter of a pound is placed on the sensor. I do find good sensors online, but many of which I am unsure whether they can "zero out" kind of how I wish them to, does anyone know any good suggestions online (preferably amazon) or other types of sensors I can use for this project? Thanks.

pert

Yes, you can do that with any sensor. If you are using a library, such as:
https://github.com/bogde/HX711
the scale will be "zeroed out" (the correct term is "tared") when the program starts. That library also has a tare() function that you can call in your sketch if you want to tare the scale at any other time. If you aren't using a library, you can simply write your own tare code.

The options I know of are:
  • A load cell and a HX711 module.
  • A force sensitive resistor (FSR).


There are square FSRs around the dimensions you want. I'm not aware of load cells in the configuration you are looking for, but you could make your own by mounting a platform to a load cell.

As for other sensors you might find, you definitely want to do some research to see how easy it will be to interface them with an Arduino.

wvmarle

FSR seems appropriate.

Not really precise, but much cheaper and easier to set up than a load cell, and good enough to detect "cup" vs. "no cup".
Quality of answers is related to the quality of questions. Good questions will get good answers. Useless answers are a sign of a poor question.

StutteringJack

Yes, you can do that with any sensor. If you are using a library, such as:
https://github.com/bogde/HX711
the scale will be "zeroed out" (the correct term is "tared") when the program starts. That library also has a tare() function that you can call in your sketch if you want to tare the scale at any other time. If you aren't using a library, you can simply write your own tare code.

The options I know of are:
  • A load cell and a HX711 module.
  • A force sensitive resistor (FSR).


There are square FSRs around the dimensions you want. I'm not aware of load cells in the configuration you are looking for, but you could make your own by mounting a platform to a load cell.

As for other sensors you might find, you definitely want to do some research to see how easy it will be to interface them with an Arduino.
This is perfect! Thanks man, but just to confirm, I could use the library with something like this?:
https://www.amazon.com/Adafruit-Square-Force-Sensitive-Resistor-FSR/dp/B00SK694YE/ref=pd_sbs_328_t_2/144-7103548-8223032?_encoding=UTF8&pd_rd_i=B00SK694YE&pd_rd_r=1e3b82c2-5b3b-4ae7-8814-9e57ad4f6724&pd_rd_w=gvQYg&pd_rd_wg=AAP4x&pf_rd_p=5cfcfe89-300f-47d2-b1ad-a4e27203a02a&pf_rd_r=N8ME84M9FC87FRW87CY0&psc=1&refRID=N8ME84M9FC87FRW87CY0

StutteringJack

I'm also still fairly new to Arduino, and programming all together, how can I use this library with a FSR? After scimming through the README I couldn't find any information about using it with an FSR.

slipstick

If you mean the HX711 library then no you can't use it with an FSR. But FSRs are easy to use so you really don't need a library. Do a search for "Arduino FSR" or just have a look at Adafruits tutorial page (with example programs) https://learn.adafruit.com/force-sensitive-resistor-fsr

Steve

wvmarle

An FSR needs a pull-up resistor and then you just use analogRead() to read it. That's all.
Quality of answers is related to the quality of questions. Good questions will get good answers. Useless answers are a sign of a poor question.

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