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Trouble reading load cell into Arudino Due using 16-bit ADC


GNK
 GNK
(@gnk)
Active Member
Joined: 4 months ago
Posts: 12
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Hi everyone,
Having a bit of trouble with the Arduino project we crafted in Canada then brought to Europe. 
 
We have a load cell that is powered by 24v DC, read by a 16-bit ADC board that then is read by an Arduino Due which is powered through my laptop USB. The load cell seems fine. I can read a signal from its amp at any time and the signal changes appropriately when I add load to the load cell. The ADC seems good too. When there is no power to the load cell, the ADC will continually give an output to the serial monitor (so I don't think it's fried). 
 
This issue is when the load cell is switched on. The ADC will print to the serial monitor for a few cycles (1, 4, 10 - the number seems random) and then the program stops. It is supposed to run continuously - spitting out values. The program I'm using is simply the example code that comes with the ADC library for a differential output on pins 2 and 3 (Adafruit ADS1x15).
 
Any idea why the ADC or the program the reads the ADC would just quit like this when the load cell is powered? 
 

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DaveE
(@davee)
Estimable Member
Joined: 8 months ago
Posts: 226
 

Hi @gnk,

  Sorry to hear you have a problem, but I suspect more information is required for anyone to have a reasonable chance of diagnosis. In particular, describing your hardware setup in more detail, as well as attaching a software listing.

As a first stab in the dark, I note you say the load cell power is 24Vdc, which leads me to wonder what the output voltage going to the ADC is.

You don't describe the ADC, but most chip ADCs expect voltages to be quite low ... typically 1-3V max. Obviously, your system may include intermediate circuitry to deal with this situation.

Is there any chance the voltage going to the ADC is causing it to hang up?

It is common for a simple program to start an ADC conversion, then wait for the ADC to report that a new conversion result is available. If the ADC 'hangs' and fails to indicate the new conversion for some reason, a simple program may wait forever.

Good luck. Dave


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