TMS320F28069: ADC READ

kapil mulchandani

Part Number: TMS320F28069

I'm trying to read sine wave on ADC pin 2. But I m not getting the expected result.value on that pin is coming same whether I apply sinewave or not.

here's my code :

#include "DSP28x_Project.h"
float Temp,voltage;
void main()
{
InitSysCtrl();
DINT;
InitPieCtrl();
IER=0x0000;
IFR=0x0000;
InitPieVectTable();
InitAdc();
EALLOW;
AdcRegs.ADCCTL2.bit.ADCNONOVERLAP = 1;
AdcRegs.ADCCTL1.bit.INTPULSEPOS = 1;
AdcRegs.ADCSOC0CTL.bit.CHSEL=2;
AdcRegs.ADCSOC0CTL.bit.ACQPS=6;
AdcRegs.INTSEL1N2.bit.INT1SEL=0;
AdcRegs.INTSEL1N2.bit.INT1E=1;
EDIS;

for(;;)
{
AdcRegs.ADCSOCFRC1.all=1;

while(AdcRegs.ADCINTFLG.bit.ADCINT1==0){}

AdcRegs.ADCINTFLGCLR.bit.ADCINT1=1;
Temp=AdcResult.ADCRESULT0;
voltage = Temp/890.041;

}
}

over 6 years ago

0 Gautam Iyer over 6 years ago

Guru 192875 points

Hi Kapil,

kapil mulchandani said:
But I m not getting the expected result.

How did you verify this?

Also, what is your sine wave frequency?

Regards,

Gautam

0 kapil mulchandani over 6 years ago in reply to Gautam Iyer

Prodigy 80 points

Hi Gautam,
I'm observing the sine wave on DSO.
My sine wave frequency is 50.02Hz
When I apply sine wave to adc pin, the value I get is same whether I apply a sine wave to it or not.
And My sine wave base level is not zero , it's 2.5v . But still ADC pin is showing Zero value.

0 Gautam Iyer over 6 years ago in reply to kapil mulchandani

Guru 192875 points

kapil mulchandani said:
When I apply sine wave to adc pin, the value I get is same whether I apply a sine wave to it or not.
And My sine wave base level is not zero , it's 2.5v . But still ADC pin is showing Zero value.

Are you referring to any sample code?

0 kapil mulchandani over 6 years ago in reply to Gautam Iyer

Prodigy 80 points

I tried using the sample code AdcSoc. But i'm not getting the result.

0 Nabil Saheb over 6 years ago in reply to kapil mulchandani

TI__Prodigy 540 points

Hi Kapil

How are you confirming the ADC conversion has taken place? On the sample code AdcSoc, after starting the code and waiting for a couple seconds, then Suspending (ALT + F8), where do you see the code stop in the sample code? When looking at the Voltage1 variable in the Expressions window, what values do you see?

-Nabil

0 kapil mulchandani over 6 years ago in reply to Nabil Saheb

Prodigy 80 points

Hi Nabil,

How can I confirm whether the conversion has taken place? Usually I wait for some time and then suspend(ALT+F8) the code.

When I run the AdcSoc example code and suspend it after a while , I find that the code has exited the for loop , where loopcount is bieng incremented and in the expression window the value for Voltage1 is between 2400 to 2700 , its showing the same value whether I apply a sine wave to the adc pin or not?

Please help me with it .

0 Nabil Saheb over 6 years ago in reply to kapil mulchandani

TI__Prodigy 540 points

Kapil

1. Can you confirm you are applying the voltage to the right pin?

2. What you see if you connect the ADCIN pin to a ground on the board?

Regards

Nabil

0 kapil mulchandani over 6 years ago in reply to Nabil Saheb

Prodigy 80 points

Hi Nabil,

I'm applying the voltage to correct pin. When I ground the ADC pin it shows zero value for the example code AdcSoc, but for my code which I have posted above in the query, it shows reading from 1 to 5.

can you help where my code is wrong?

0 Nabil Saheb over 6 years ago in reply to kapil mulchandani

TI__Prodigy 540 points

Kapil

What board are you using? Is this from TI or one you've built? Are you looking at the same ADCIN pin being used in the AdcSoc example code since we know the AdcSoc code is working correctly on your setup?

-Nabil

0 kapil mulchandani over 6 years ago in reply to Nabil Saheb

Prodigy 80 points

I'm using the texas piccolo, f28069 experimental board. yes, i'm looking on the correct pin i.e. ADC4 and ADC2. I have checked on both the pins. Can you help me, how to read ADC using Software trigger because in AdcSoc example, triggering by epwm is used. I have used Software trigger method in my code what's wrong in that?