PathakS
Newbie level 3
Hello,
I am using AD7730 IC to read load cell data. I am trying to calibrate AD7730 ic using MV generator.The output range is 0 to 20 mV in unipolar mode.
The calibration procedure I have done is as follows:-
1) System zero scale calibration on 0 to 80mV range when Ain+ve and Ain-ve terminals are open. nothing will be connected here.after doing system zero scale calibration the value I get is 3mV.
2) System zero-scale calibration on 0 to 20mV range.set "0" on mV generator.the value I get after system zero scale calibration is 0.02mV
3) System full scale calibration on no range selected.set "20mV" on mV generator.The value I get after system full scale calibration is 20mV
The value I get during Zero scale calibration is 0V and during full scale calibration is 20mV.
after performing calibration I am trying to read voltages from 0 to 20mV which is set on mV generator but the value I get in resistor are different.
When I set 11.80mV on mV generator in resistor I get 0xFFFFFF ( 20mV).It means instead of showing 0xFFFFFF on 20mV it will shows on 11.80mV.
I am using AD7730 IC to read load cell data. I am trying to calibrate AD7730 ic using MV generator.The output range is 0 to 20 mV in unipolar mode.
The calibration procedure I have done is as follows:-
1) System zero scale calibration on 0 to 80mV range when Ain+ve and Ain-ve terminals are open. nothing will be connected here.after doing system zero scale calibration the value I get is 3mV.
Code dot - [expand] 1 2 3 4 5 // internal Full-scale calibration WriteRegister(CR_SINGLE_WRITE|CR_MODE_REGISTER,2,MR1_MODE_INTERNAL_FULL_CALIBRATION| MR1_BU_UNIPOLAR|MR1_WL_24_BIT|MR0_HIREF_5V|MR0_RANGE_80MV|MR0_CHANNEL_1); while(!((P2IN&BIT0)==0)){} //wait for calibration complete __delay_cycles (200);
2) System zero-scale calibration on 0 to 20mV range.set "0" on mV generator.the value I get after system zero scale calibration is 0.02mV
Code dot - [expand] 1 2 3 4 5 // system zero-scale calibration WriteRegister(CR_SINGLE_WRITE|CR_MODE_REGISTER,2,MR1_MODE_SYSTEM_ZERO_CALIBRATION| MR1_BU_UNIPOLAR|MR1_WL_24_BIT|MR0_HIREF_5V|MR0_RANGE_20MV|MR0_CHANNEL_1); while(!((P2IN&BIT0)==0)){} //wait for calibration complete __delay_cycles (200);//200
3) System full scale calibration on no range selected.set "20mV" on mV generator.The value I get after system full scale calibration is 20mV
Code dot - [expand] 1 2 3 4 5 // system full-scale calibration WriteRegister(CR_SINGLE_WRITE|CR_MODE_REGISTER,2,MR1_MODE_SYSTEM_FULL_CALIBRATION| MR1_BU_UNIPOLAR|MR1_WL_24_BIT|MR0_HIREF_5V|MR0_CHANNEL_1); while(!((P2IN&BIT0)==0)){} //wait for calibration complete __delay_cycles (200);
The value I get during Zero scale calibration is 0V and during full scale calibration is 20mV.
after performing calibration I am trying to read voltages from 0 to 20mV which is set on mV generator but the value I get in resistor are different.
When I set 11.80mV on mV generator in resistor I get 0xFFFFFF ( 20mV).It means instead of showing 0xFFFFFF on 20mV it will shows on 11.80mV.
Please help me where I am going wrong??Calculations:-
LoadCellData = ReadData();
LoadCellData1=LoadCellData;
milivolt1 = (LoadCellData1*20)/(2^24);
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