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Hi all, I purchased a C2000 microcontroller with its controlcard as well as the experimenter's kit. When I tried to use ADC of the MCU, I met following problem:
I tried to connect the ADC to a wave generator. The waveform was generated by National Instrument's DAQ NI-USB-6356 (analog output).
Basically, I copied the example code for the MCU. I set the ADC to continuous sampling mode, and stored 512 sampling points to the memory. Then, I use the UART port to show the value of the 512 points to the terminal (which is on my host computer).
I used 16bit, single ended ADC setup. The connection is illustrated below:
I found the ADC's result was quite noisy. The result is shown below:
Here is the code I used:
do
{
//
//enable ADCINT flags
//
EALLOW;
AdcaRegs.ADCINTSEL1N2.bit.INT1E = 1;
AdcaRegs.ADCINTSEL1N2.bit.INT2E = 1;
AdcaRegs.ADCINTSEL3N4.bit.INT3E = 1;
AdcaRegs.ADCINTSEL3N4.bit.INT4E = 1;
AdcaRegs.ADCINTFLGCLR.all = 0x000F;
EDIS;
//
//initialize results index
//
resultsIndex = 0;
//
//software force start SOC0 to SOC7
//
AdcaRegs.ADCSOCFRC1.all = 0x00FF;
//
//keep taking samples until the results buffer is full
//
while(resultsIndex < RESULTS_BUFFER_SIZE)
{
//
//wait for first set of 8 conversions to complete
//
while(0 == AdcaRegs.ADCINTFLG.bit.ADCINT3);
//
//clear both INT flags generated by first 8 conversions
//
AdcaRegs.ADCINTFLGCLR.bit.ADCINT1 = 1;
AdcaRegs.ADCINTFLGCLR.bit.ADCINT3 = 1;
//
//save results for first 8 conversions
//
//note that during this time, the second 8 conversions have
//already been triggered by EOC6->ADCIN1 and will be actively
//converting while first 8 results are being saved
//
AdcaResults[resultsIndex++] = AdcaResultRegs.ADCRESULT0;
AdcaResults[resultsIndex++] = AdcaResultRegs.ADCRESULT1;
AdcaResults[resultsIndex++] = AdcaResultRegs.ADCRESULT2;
AdcaResults[resultsIndex++] = AdcaResultRegs.ADCRESULT3;
AdcaResults[resultsIndex++] = AdcaResultRegs.ADCRESULT4;
AdcaResults[resultsIndex++] = AdcaResultRegs.ADCRESULT5;
AdcaResults[resultsIndex++] = AdcaResultRegs.ADCRESULT6;
AdcaResults[resultsIndex++] = AdcaResultRegs.ADCRESULT7;
//
//wait for the second set of 8 conversions to complete
//
while(0 == AdcaRegs.ADCINTFLG.bit.ADCINT4);
//
//clear both INT flags generated by second 8 conversions
//
AdcaRegs.ADCINTFLGCLR.bit.ADCINT2 = 1;
AdcaRegs.ADCINTFLGCLR.bit.ADCINT4 = 1;
//
//save results for second 8 conversions
//
//note that during this time, the first 8 conversions have
//already been triggered by EOC14->ADCIN2 and will be actively
//converting while second 8 results are being saved
//
AdcaResults[resultsIndex++] = AdcaResultRegs.ADCRESULT8;
AdcaResults[resultsIndex++] = AdcaResultRegs.ADCRESULT9;
AdcaResults[resultsIndex++] = AdcaResultRegs.ADCRESULT10;
AdcaResults[resultsIndex++] = AdcaResultRegs.ADCRESULT11;
AdcaResults[resultsIndex++] = AdcaResultRegs.ADCRESULT12;
AdcaResults[resultsIndex++] = AdcaResultRegs.ADCRESULT13;
AdcaResults[resultsIndex++] = AdcaResultRegs.ADCRESULT14;
AdcaResults[resultsIndex++] = AdcaResultRegs.ADCRESULT15;
}
//
//disable all ADCINT flags to stop sampling
//
EALLOW;
AdcaRegs.ADCINTSEL1N2.bit.INT1E = 0;
AdcaRegs.ADCINTSEL1N2.bit.INT2E = 0;
AdcaRegs.ADCINTSEL3N4.bit.INT3E = 0;
AdcaRegs.ADCINTSEL3N4.bit.INT4E = 0;
EDIS;
for(i=0;i<RESULTS_BUFFER_SIZE;i++)
{
scia_xmit_int(AdcaResults[i]);
}
//
//at this point, AdcaResults[] contains a sequence of conversions
//from the selected channel
//
//
//software breakpoint, hit run again to get updated conversions
//
//asm(" ESTOP0");
scia_xmit('\n');
scia_xmit('\n');
scia_xmit('\n');
DELAY_US(5000000);
}while(1); do
{
//
//enable ADCINT flags
//
EALLOW;
AdcaRegs.ADCINTSEL1N2.bit.INT1E = 1;
AdcaRegs.ADCINTSEL1N2.bit.INT2E = 1;
AdcaRegs.ADCINTSEL3N4.bit.INT3E = 1;
AdcaRegs.ADCINTSEL3N4.bit.INT4E = 1;
AdcaRegs.ADCINTFLGCLR.all = 0x000F;
EDIS;
//
//initialize results index
//
resultsIndex = 0;
//
//software force start SOC0 to SOC7
//
AdcaRegs.ADCSOCFRC1.all = 0x00FF;
//
//keep taking samples until the results buffer is full
//
while(resultsIndex < RESULTS_BUFFER_SIZE)
{
//
//wait for first set of 8 conversions to complete
//
while(0 == AdcaRegs.ADCINTFLG.bit.ADCINT3);
//
//clear both INT flags generated by first 8 conversions
//
AdcaRegs.ADCINTFLGCLR.bit.ADCINT1 = 1;
AdcaRegs.ADCINTFLGCLR.bit.ADCINT3 = 1;
//
//save results for first 8 conversions
//
//note that during this time, the second 8 conversions have
//already been triggered by EOC6->ADCIN1 and will be actively
//converting while first 8 results are being saved
//
AdcaResults[resultsIndex++] = AdcaResultRegs.ADCRESULT0;
AdcaResults[resultsIndex++] = AdcaResultRegs.ADCRESULT1;
AdcaResults[resultsIndex++] = AdcaResultRegs.ADCRESULT2;
AdcaResults[resultsIndex++] = AdcaResultRegs.ADCRESULT3;
AdcaResults[resultsIndex++] = AdcaResultRegs.ADCRESULT4;
AdcaResults[resultsIndex++] = AdcaResultRegs.ADCRESULT5;
AdcaResults[resultsIndex++] = AdcaResultRegs.ADCRESULT6;
AdcaResults[resultsIndex++] = AdcaResultRegs.ADCRESULT7;
//
//wait for the second set of 8 conversions to complete
//
while(0 == AdcaRegs.ADCINTFLG.bit.ADCINT4);
//
//clear both INT flags generated by second 8 conversions
//
AdcaRegs.ADCINTFLGCLR.bit.ADCINT2 = 1;
AdcaRegs.ADCINTFLGCLR.bit.ADCINT4 = 1;
//
//save results for second 8 conversions
//
//note that during this time, the first 8 conversions have
//already been triggered by EOC14->ADCIN2 and will be actively
//converting while second 8 results are being saved
//
AdcaResults[resultsIndex++] = AdcaResultRegs.ADCRESULT8;
AdcaResults[resultsIndex++] = AdcaResultRegs.ADCRESULT9;
AdcaResults[resultsIndex++] = AdcaResultRegs.ADCRESULT10;
AdcaResults[resultsIndex++] = AdcaResultRegs.ADCRESULT11;
AdcaResults[resultsIndex++] = AdcaResultRegs.ADCRESULT12;
AdcaResults[resultsIndex++] = AdcaResultRegs.ADCRESULT13;
AdcaResults[resultsIndex++] = AdcaResultRegs.ADCRESULT14;
AdcaResults[resultsIndex++] = AdcaResultRegs.ADCRESULT15;
}
//
//disable all ADCINT flags to stop sampling
//
EALLOW;
AdcaRegs.ADCINTSEL1N2.bit.INT1E = 0;
AdcaRegs.ADCINTSEL1N2.bit.INT2E = 0;
AdcaRegs.ADCINTSEL3N4.bit.INT3E = 0;
AdcaRegs.ADCINTSEL3N4.bit.INT4E = 0;
EDIS;
for(i=0;i<RESULTS_BUFFER_SIZE;i++)
{
scia_xmit_int(AdcaResults[i]);
}
//
//at this point, AdcaResults[] contains a sequence of conversions
//from the selected channel
//
//
//software breakpoint, hit run again to get updated conversions
//
//asm(" ESTOP0");
scia_xmit('\n');
scia_xmit('\n');
scia_xmit('\n');
DELAY_US(5000000);
}while(1);
