TMS320F280025C: ADC not read the value

Part Number: TMS320F280025C

Hello,

   I need to read the voltage in the ADC interrupt service routine. ADC interrupt is being  triggered. When I connect the ADC pin to 3.3V and ground, the ADC reads the voltage correctly. I have connected the ADC pin to a potentiometer. Currently, the potentiometer's output voltage is 1.8V, but the ADC reading in Code Composer Studio shows 0. When I measure the voltage at the controller's pin with a multimeter, it shows 1.8V correctly.

I am using ADCA3/C5

I am attaching code for your reference purpose:-

#include "f28x_project.h"

//
// Defines
//
#define RESULTS_BUFFER_SIZE 256

//
// Globals
//
uint16_t sensorSample = 0;
uint16_t isrCount = 0;
int16_t sensorTemp = 0;

//
// Function Prototypes
//
void initADC(void);
void initEPWM(void);
void initADCSOC(void);
__interrupt void AdcA1ISR(void);

//
// Main
//
void main(void)
{
//
// Initialize device clock and peripherals
//
InitSysCtrl();

//
// Initialize GPIO
//
InitGpio();

//
// Disable CPU interrupts
//
DINT;

//
// Initialize the PIE control registers to their default state.
// The default state is all PIE interrupts disabled and flags
// are cleared.
//
InitPieCtrl();

//
// Disable CPU interrupts and clear all CPU interrupt flags:
//
IER = 0x0000;
IFR = 0x0000;

//
// Initialize the PIE vector table with pointers to the shell Interrupt
// Service Routines (ISR).
//
InitPieVectTable();

//
// Map ISR functions
//
EALLOW;
PieVectTable.ADCA1_INT = &AdcA1ISR; // Function for Adca interrupt 1
EDIS;

//
// Configure the ADC and power it up
//
initADC();

//
// Configure the ePWM
//
initEPWM();

//
// Setup the ADC for ePWM triggered conversions on channel 1
//
initADCSOC();


EALLOW;

//
// Enable PIE interrupt
//
PieCtrlRegs.PIEIER1.bit.INTx1 = 1;

//
// Sync ePWM
//
CpuSysRegs.PCLKCR0.bit.TBCLKSYNC = 1;

//
// Enable global Interrupts and higher priority real-time debug events:
//
IER |= M_INT1; // Enable group 1 interrupts

EINT; // Enable Global interrupt INTM
ERTM; // Enable Global realtime interrupt DBGM

InitTempSensor(3.3f);

//
// Start ePWM
//
EPwm1Regs.ETSEL.bit.SOCAEN = 1; // Enable SOCA
EPwm1Regs.TBCTL.bit.CTRMODE = 0; // Unfreeze, and enter up count mode

//
// Wait while ePWM causes ADC conversions, which then cause interrupts,
// which fill the results buffer, eventually setting the bufferFull
// flag
//
while(1)
{
}
}

//
// initADC - Function to configure and power up Adca.
//
void initADC(void)
{
//
// Setup VREF as internal
//
SetVREF(ADC_ADCA, ADC_EXTERNAL, ADC_VREF3P3);

EALLOW;

//
// Set AdcaLK divider to /4
//
AdcaRegs.ADCCTL2.bit.PRESCALE = 6;

//
// Set pulse positions to late EOC
//
AdcaRegs.ADCCTL1.bit.INTPULSEPOS = 1;

//
// Power up the ADC and then delay for 1 ms
//
AdcaRegs.ADCCTL1.bit.ADCPWDNZ = 1;
EDIS;

DELAY_US(1000);
}

//
// initEPWM - Function to configure ePWM1 to generate the SOC.
//
void initEPWM(void)
{
EALLOW;

EPwm1Regs.ETSEL.bit.SOCAEN = 0; // Disable SOC on A group
EPwm1Regs.ETSEL.bit.SOCASEL = 4; // Select SOC on up-count
EPwm1Regs.ETPS.bit.SOCAPRD = 1; // Generate pulse on 1st event

EPwm1Regs.CMPA.bit.CMPA = 0x0800; // Set compare A value to 2048 counts
EPwm1Regs.TBPRD = 0x1000; // Set period to 4096 counts

EPwm1Regs.TBCTL.bit.CTRMODE = 3; // Freeze counter

EDIS;
}

//
// initADCSOC - Function to configure ADCA's SOC0 to be triggered by ePWM1.
//
void initADCSOC(void)
{
//
// Select the channels to convert and the end of conversion flag
//
EALLOW;

AdcaRegs.ADCSOC0CTL.bit.CHSEL = 0x03; // SOC0 will convert pin C12

AdcaRegs.ADCSOC0CTL.bit.ACQPS = 19; // Sample window is 10 SYSCLK cycles
AdcaRegs.ADCSOC0CTL.bit.TRIGSEL = 5; // Trigger on ePWM1 SOCA

AdcaRegs.ADCINTSEL1N2.bit.INT1SEL = 0; // End of SOC0 will set INT1 flag
AdcaRegs.ADCINTSEL1N2.bit.INT1E = 1; // Enable INT1 flag
AdcaRegs.ADCINTFLGCLR.bit.ADCINT1 = 1; // Make sure INT1 flag is cleared

EDIS;
}

//
// Adca1ISR - ADC C Interrupt 1 ISR
//
__interrupt void AdcA1ISR(void)
{

isrCount++;

if (isrCount==1000)
{
isrCount=0;
}
//
// Add the latest result to the buffer
// ADCRESULT0 is the result register of SOC0
sensorSample = AdcaResultRegs.ADCRESULT0;
// sensorTemp = GetTemperatureC(sensorSample);

//
// Clear the interrupt flag
//
AdcaRegs.ADCINTFLGCLR.bit.ADCINT1 = 1;

//
// Check if overflow has occurred
//
if(1 == AdcaRegs.ADCINTOVF.bit.ADCINT1)
{
AdcaRegs.ADCINTOVFCLR.bit.ADCINT1 = 1; //clear INT1 overflow flag
AdcaRegs.ADCINTFLGCLR.bit.ADCINT1 = 1; //clear INT1 flag
}

//
// Acknowledge the interrupt
//
PieCtrlRegs.PIEACK.all = PIEACK_GROUP1;
}

Please let me know why I am not able to read adc voltage??