Connecting multiple load cells to the same microcontroller

Question

This is my first post and I am a little bit confused about one thing. I would need to do the following project: have about 5-6 load cells to be connected to a microcontroller. I am not sure if there is a way to connect multiple load cells to the same arduino. I would need each load cell to act individually, so I would need an individual result from all each load cell.

I believe I would need to connect 1 load cell to 1 load cell amp and then connect the load cell amp to the Arduino and repeat this process 5-6 times (for each load cell that I need)

I'm not sure if this is possible using one Arduino or I would need 1 Arduino for each individual load cell.

The main idea of the project is to have a load cell to be placed under different kitchen supplies (1 load cell to continuously check the weight of Flower, another one to check for bread, another to check for paprika, and so on)

After this is read from the sensors, I need to write the weight of each item in a table / DB every 30 minutes.

Also, if this can be done with another board, like a microcontroller (Raspberry Pi) I'm open to that.

Answer 1

All you need is the following :

• Arduino (Mega, if you need alot of inputs.)
• Load Cell Amplifier
• Load Cells (I recommend only using four wire cells)
• Resistors (Only if you are connecting one cell to one amplifier)

If you are using only one load cell per "Scale" , you would connect it as you say correctly. One load cell to each load cell amplifier and then to the Arduino.

Yes, a single Arduino can in theory take as many scales as the number of Digital inputs you have can provide. You can use the Analog inputs as well but from my experience I would recommend you only use the Digital inputs. You can just share the power and ground sources.

Usually each Load Cell Amplifier will need to use two(2) Digital inputs.

If you want to use multiple load cells together (to improve accuracy) to act as a single scale, you would connect them together in what they call a Quarter, Half or Full Bridge wiring configuration depending on how many you would like working together.

You can write to a DB if you want sure. What I personally like to do is send the readings to the cloud using dweet.io or ThingSpeak. ThingSpeak.com would probably be best for you.

I usually use the NodeMCU arduino boards that have WiFi built in. They are cheap and work great.

I hope this helps.

Answer 2

I had a similar project awhile back that involved multiple flex sensors. I ultimately had to use multiple op amps to boost each signal from the flex sensors. Some IC contain multiple op-amps though which will lessen your circuit footprint.
Each output of the op amp was run to a separate ADC channels on an Arduino. Depending on your Arduino you should have 8 (mini) - 16 (mega) analog pins to read your sensors.

Answer 3

You can use multiplexers to multiplex the loadcells and you can select the loadcells using only less selector pins