ADS1230 interfacing 8052

Dear Bob,

  I need to clarify one doubt regarding the precision in the ADC calculation.my formula looks like:-

weight =  ( updated_counts - no_load_counts) * my_data;     //TARE function not included..

were; "my_data" is the calibrated value ,i.e      my_data = cal_weight /  (adc_counts - no_load_counts);

My problem is, when i put a weight on the pan.suppose 1kg ,the display varies in between 0.999 gms and 1.000 gms. I observed that the noise in the layout is minimum, by observing the internal counts(changes in between 4 - 5 counts only).

From my calculation the result is obtaining like this:

suppose

no_load_counts = 10500;  // For 1 kilogram weight

updated_counts = 28650;

my_data = (1000 / (28650 - 10500)); = 0.0559641873278236914600550964187  //calibrated value with 1 kilogram weight.

 So as per the above formula the weight is calculated for 1 kilogram is given by:

weight =  ( updated_counts - no_load_counts) * my_data;     // TARE function not included..

weight = (28650 - 10500) * 0.0559641873278236914600550964187 = 1000 gms.

So here when the updated_counts are changed 1 or 2 counts due to noise the result will be

weight = (28649 - 10500) * 0.0559641873278236914600550964187 = 999.9449036;

Therefore displayed weight = 0.999 gms

Here i lost around 1 gram for 1 count variation,This small changes in the counts are reflecting on the external counts,Please help me to solve this problem.I used all the variables excluding my_data are of int datatype .my_data is a float datatype.

I m expecting your valuable reply.

Thank you

by

Ajit..