Load Cell Data Acquisiton with Arduino

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1

Hi;

I am building a project with a load cell (wheatstone bridge) and I intend to use the arduino to do the reading of response in voltage generates. I had some questions about how to do the data acquisition of response in voltage of load cell, as below:

I realized with a multimeter, that the response in voltage of load cell is about of 1 mV to 1.9 mV. What pins (signal positive and signal negative) do I have to connect to read the voltage of load cell? Digital or analog?

The response in voltage is too low (1 mV to 1.9 mV). Do I have to do some electronic amplifier or electronic connection between arduino and load cell to read this response? Or could I connect directly the load cell and the arduino?

Regards.

2

The arduino analog inputs can measure 0 to 5V and return a value 0 to 1023. A quick calculation shows that 1 count is about 5mv so you will need some kind of amplifier to boost the voltage from the load cell before feeding it to the analog input.

If you put "arduino load cell amplifier" into your favorite search engine you will find lots of info.

3

Find an HX711 module for the amplification; very cheap and very high precision. Avoid any recommendation that suggests an INA129 or similar.

4

Chagrin:
Avoid any recommendation that suggests an INA129 or similar.

I'm sorry for the question in a very old topic, but, why avoid those recommendations?

I'm development a board with INA125P and ADS1252 for use with arduino (wheatstone bridge) and I became curios.

5

I see a lot of attempts to use InAmps with just the analog output -- no precision A/D converter -- and then the reliance on the Arduino's 10 bit A/D converter results in accuracy that is terrible. If you're using load cells the HX711 is so cheap and well-tailored to the task that it's unarguably the best place to start.

I wouldn't disrespect your plan to use an INA125 with the ADS1252, however; it would be a much more flexible option and capable of handling more problems than just load cells given the much greater ability to control the gain. Building something like that is not the way to go for a novice, though.