CCS/TMS320F28377S: DSP-28377S-ADC-Sampling error

Tool/software: Code Composer Studio

Dear all;

I am using the DSP-28377S , Now I fond the ADC value is not right.  I used  50 DSP  chips, the same software, There are 20  right , 30 are error. As follows:

DSP-ADC:

 1、ADC_RESOLUTION_16BIT,      ADC_SIGNALMODE_DIFFERENTIAL

2、red curve is ADC-A0-A1 channel,  white is ADC-A2-A3 channel, green is  ADC-A4-A5 channel, 

3、the red curve value (A0-A1 channel)  is  always correct. 

erro:

correct:

Code:

void ADC_capture()
{


AdcaRegs.ADCSOCFRC1.all = 0x007F; //SOC0 and SOC1

while(AdcaRegs.ADCINTFLG.bit.ADCINT1 == 0);

AdcaRegs.ADCINTFLGCLR.bit.ADCINT1 = 1；



AdcaResult0 = AdcaResultRegs.ADCRESULT0; ///1--3

AdcaResult2 = AdcaResultRegs.ADCRESULT2;

AdcaResult4 = AdcaResultRegs.ADCRESULT4;

}




//Write ADC configurations and power up the ADC for both ADC A and ADC B
void ConfigureADC(void)
{

EALLOW;

//write configurations
AdcaRegs.ADCCTL2.bit.PRESCALE = 6;   //set ADCCLK divider to /4

AdcSetMode(ADC_ADCA, ADC_RESOLUTION_16BIT, ADC_SIGNALMODE_DIFFERENTIAL);

AdcaRegs.ADCCTL1.bit.INTPULSEPOS = 1; // AdcaRegs.ADCCTL1.bit.INTPULSEPOS = 1;

AdcaRegs.ADCCTL1.bit.ADCPWDNZ = 1;

EDIS;


}

















void SetupADCSoftware(void)
{

Uint16 acqps;

//determine minimum acquisition window (in SYSCLKS) based on resolution
if( 0 && ADC_RESOLUTION_12BIT == AdcaRegs.ADCCTL2.bit.RESOLUTION){
acqps = 14; //75ns
}
else { //resolution is 16-bit
acqps = 63; //63--320nS 
}

//Select the channels to convert and end of conversion flag
//------------------ADCA-------------------------------------------------------
EALLOW;

AdcaRegs.ADCSOC0CTL.bit.CHSEL = 0; //SOC0 will convert pin A0
AdcaRegs.ADCSOC0CTL.bit.ACQPS = acqps; //sample win




AdcaRegs.ADCSOC1CTL.bit.CHSEL = 1; //SOC1 will convert pin A1
AdcaRegs.ADCSOC1CTL.bit.ACQPS = acqps; //sample window is acqps + 1 SYSCLK cycles
// AdcbRegs.ADCSOC1CTL.bit.TRIGSEL = 1;



AdcaRegs.ADCSOC2CTL.bit.CHSEL = 2; //SOC1 will convert pin A1
AdcaRegs.ADCSOC2CTL.bit.ACQPS = acqps; //sample window is acqps + 1 SYSCLK cycles
//AdcbRegs.ADCSOC2CTL.bit.TRIGSEL = 1;



AdcaRegs.ADCSOC3CTL.bit.CHSEL = 3; //SOC1 will convert pin A1
AdcaRegs.ADCSOC3CTL.bit.ACQPS = acqps; //sample window is acqps + 1 SYSCLK cycles




AdcaRegs.ADCSOC4CTL.bit.CHSEL = 4; //SOC1 will convert pin A1
AdcaRegs.ADCSOC4CTL.bit.ACQPS = acqps; //sample window is acqps + 1 SYSCLK cycles
//AdcbRegs.ADCSOC4CTL.bit.TRIGSEL = 1;



AdcaRegs.ADCSOC5CTL.bit.CHSEL = 5; //SOC1 will convert pin A1
AdcaRegs.ADCSOC5CTL.bit.ACQPS = acqps; //sample window is acqps + 1 SYSCLK cycles




AdcaRegs.ADCINTSEL1N2.bit.INT1SEL = 5; //end of SOC1 will set INT1 flag
AdcaRegs.ADCINTSEL1N2.bit.INT1E = 1; //enable INT1 flag
AdcaRegs.ADCINTFLGCLR.bit.ADCINT1= 1; //make sure INT1 flag is cleared

}

I can not found why it is, Please. Thanks.