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ADS1230 interfacing pic16f877a

ajith kumar
Intellectual 320 points

Other Parts Discussed in Thread: ADS1230

Dear Bob,

  Thank you for your quick reply...Actually in my project interfacing pic16f877a interfacing ADS1230,I m using 6Kg load cell.So i can easily achieve the accuracy of 1gram.But if i m using the larger capacity load cell (example:50kg,100kg capacity) its difficult to get 1 gram accuracy,so its better to use 5 gram  accuracy(i.e. each division shows 5 gram  ).So the reading shows like 00000,00005,00010,00015....etc.

       But my reading looks like 00000,00001,00002,00003......etc(i.e. 1 gram division).

So my doubt is how to make 5 gram division, if i m using 50kg load cell.That is i need the readings like 00000,00005,00010,00015,00020....etc.

      So what  change should i make in my formula...Please Help....Thanks IN ADVANCE..

                                                        By 

Ajith.

  • 0
    TI__Guru** 113765 points

    Ajith,

    Remember that you are always reading a voltage, and then converting that voltage to a weight.  So your resolution is going to be based on the number of noise free codes that reside within the range of the load cell.  Let's say you have three load cells.  One is 5kg, the second is 10kg and the third is 50kg.  Let's say they all have the same rating as far as maximum deflection (2mV/V).  Let's also assume that they will calibrate the same so that CalMax-CalMin is 50000 codes.

    Let's start with the 5kg case.  If we want to find the weight value of one code it will be the range of the load cell divided by the number of codes for full deflection (5kg/50000).  So one code will be 0.1 gram.  If we do the same for the other load cells we get 1 code equal to 0.2g for the 10kg load cell ,and 1g per code for the 50kg load cell.

    If we work this backwards and place a 10g weight on each scale, the number of codes for the 5kg scale will be 100, for the 10kg scale will be 50 and for the 50kg scale will be 10.  So your weight resolution is defined by the voltage produced from the output of the load cell for full deflection.

    Each code represents a value, and the ADS1230 will never output a value that jumps in multiples of 5.  It is the value of the code itself that changes depending on the size of the load cell being used.

    Best regards,

    Bob B