Part Number: TMS320F28377S
Hi ,
I am using TMS320F 28377S ADC. When inputting the input voltage of ADC in units of 10 mV, the result of the ADC needs to be linear, but in the system I am using, the ADC result values are not linear but cascade. What's wrong?
The adc conversion period is 10 ms, and all channels are read at once
Test result is bellow.
<Input Voltage> < ADC result>
3.40 2501
3.41 2511
3.42 2517
3.43 2518
3.44 2533
3.45 2543
My system settings are as follows
{
EALLOW;
AdcaRegs.ADCCTL2.bit.PRESCALE = 15;
AdcbRegs.ADCCTL2.bit.PRESCALE = 15;
AdcSetMode(ADC_ADCA, ADC_RESOLUTION_12BIT, ADC_SIGNALMODE_SINGLE);
AdcSetMode(ADC_ADCB, ADC_RESOLUTION_12BIT, ADC_SIGNALMODE_SINGLE);
//Set pulse positions to late
AdcaRegs.ADCCTL1.bit.INTPULSEPOS = 1;
AdcbRegs.ADCCTL1.bit.INTPULSEPOS = 1;
//power up the ADCs
AdcaRegs.ADCCTL1.bit.ADCPWDNZ = 1;
AdcbRegs.ADCCTL1.bit.ADCPWDNZ = 1;
//delay for 1ms to allow ADC time to power up
DELAY_US(1000);
//Select the channels to convert and end of conversion flag
//ADCA
AdcaRegs.ADCSOC2CTL.bit.CHSEL = 2;
AdcaRegs.ADCSOC3CTL.bit.CHSEL = 3;
AdcaRegs.ADCSOC4CTL.bit.CHSEL = 4;
AdcaRegs.ADCSOC5CTL.bit.CHSEL = 5;
AdcaRegs.ADCSOC2CTL.bit.ACQPS = 30;
AdcaRegs.ADCSOC3CTL.bit.ACQPS = 30;
AdcaRegs.ADCSOC4CTL.bit.ACQPS = 30;
AdcaRegs.ADCSOC5CTL.bit.ACQPS = 30;
AdcaRegs.ADCINTSEL1N2.bit.INT1E = 1;
AdcaRegs.ADCINTSEL1N2.bit.INT1SEL = 5;
AdcaRegs.ADCINTFLGCLR.bit.ADCINT1 = 1;
//ADCB
AdcbRegs.ADCSOC0CTL.bit.CHSEL = 0;
AdcbRegs.ADCSOC2CTL.bit.CHSEL = 2;
AdcbRegs.ADCSOC3CTL.bit.CHSEL = 3;
AdcbRegs.ADCSOC0CTL.bit.ACQPS = 30;
AdcbRegs.ADCSOC2CTL.bit.ACQPS = 30;
AdcbRegs.ADCSOC3CTL.bit.ACQPS = 30;
AdcbRegs.ADCINTSEL1N2.bit.INT1E = 1;
AdcbRegs.ADCINTSEL1N2.bit.INT1SEL = 3;
AdcbRegs.ADCINTFLGCLR.bit.ADCINT1 = 1;
EDIS;
}
adc Results read as follows
{
AdcaRegs.ADCSOCFRC1.all = 0x003C; //SOC2, 3, 4, 5
while(AdcaRegs.ADCINTFLG.bit.ADCINT1 == 0);
AdcaRegs.ADCINTFLGCLR.bit.ADCINT1 = 1;
us_resulta2 = AdcaResultRegs.ADCRESULT2;
us_resulta3 = AdcaResultRegs.ADCRESULT3;
us_resulta4 = AdcaResultRegs.ADCRESULT4;
us_resulta5 = AdcaResultRegs.ADCRESULT5;
AdcbRegs.ADCSOCFRC1.all = 0x000D; //SOC0,2,3
//wait for ADCB to complete, then acknowledge flag
while(AdcbRegs.ADCINTFLG.bit.ADCINT1 == 0);
AdcbRegs.ADCINTFLGCLR.bit.ADCINT1 = 1;
us_resultb0 = AdcbResultRegs.ADCRESULT0;
us_resultb2 = AdcbResultRegs.ADCRESULT2;
us_resultb3 = AdcbResultRegs.ADCRESULT3;
}
Please give us a little opinion on what is the problem
Thanks, Steven Kim
