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Regarding Load Cell Drift using ADS1230

Jayaraj A
Prodigy 200 points


I was able to solve my AD1230 hang, by running a 100ms timer to look for the data interrupt. If the interrupt happens, before or late 100ms, AD1230 will get a reset from the uC.

Now I am facing a new issue of load cell drift of 50 counts.

Doubting AD1230, I shorted both + & - inputs(differential inputs) and grounded. Analyzed for 2 days and found the drift count not more than 5. This is reasonable, as my design is in bread board level. So the drift is not due to my power supply source & AD1230.

Regarding Load cell Drift:

     1 week before, when I power on my unit with load cell, the initial reading, without zero(tare), was 2555 counts. But this count was not the same in the next days. One day it went to 2527 & another it went to 2503.

      My ADC reference & analog VCC & digital VCC are all from single +5V source with all the grounds shorted. ADC offset calibration done, only during power on reset.

      This load cell drift affects my initial tare. But the load cell linearity remains the same. 200 counts for 200gm, 100counts for 100gm.

      Kindly reply how to solve this initial drift issues from load cell.

 

Jayaraj.A

  • TI__Guru** 113765 points

    Jayaraj,

    I would suspect the issue to be noise related.  When the offset calibration is run, it takes a series of measurements and bases the offset on these measurements.  If there is a lot of noise in your system, then the offset value used for correction may change from time to time.

    Another factor is environment.  Temperature, atmospheric conditions and mechanical changes within the load cell will affect the no load point somewhat.  This is part of the reason why you TARE the scale.

    Best regards,

    Bob B