TMS320F28379D: F28379

Hi,

Please see our app note on ADC input circuit design: https://www.ti.com/lit/spract6

I don't think the content covered in that app note will be the cause your error, since that would normally cause your output to be lower than expected.

Are you sure that you set the graph up correctly? If you store ADC results in a buffer, are you seeing most of the samples be close to 4096? 

Are you using on of our examples? If so, which one?

Best Regards,

Ben Collier

Hi,

Yes I am using buffer and most of the samples 4095 as you said. The graph should be ok. The code is attached below. I use TI example for buffer and the left is my work. 

//###########################################################################
// Author: Halit Durukan
//###########################################################################
#include "F28x_Project.h"     // Device Headerfile and Examples Include File


#define ADC_BUF_LEN 1000

//###########################################################################
// Global variables used in the project before main function. Declare other     // variables in this section of the code.
//###########################################################################
Uint16 Result = 0;
Uint16 AdcBuf[ADC_BUF_LEN];
//###########################################################################
// Declare the service routines and functions
//###########################################################################


interrupt void xint1_isr(void);
interrupt void cpu_timer(void);
interrupt void adcint1_isr(void);

//######################   Beginning of the main code #######################


void main(void)
{

// Initialize System Control:
// PLL, WatchDog, enable Peripheral Clocks
// This example function is found in the F2837xD_SysCtrl.c file.
    InitSysCtrl();


// Clear all interrupts and initialize PIE vector table:
// 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.
// This function is found in the F2837xD_PieCtrl.c file.
    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).
// This will populate the entire table, even if the interrupt
// is not used in this example.  This is useful for debug purposes.
// The shell ISR routines are found in F2837xD_DefaultIsr.c.
// This function is found in F2837xD_PieVect.c.
    InitPieVectTable();


// Enable global Interrupts and higher priority real-time debug events:
    //EINT;  // Enable Global interrupt INTM
    //ERTM;  // Enable Global realtime interrupt DBGM


//###########################################################################
// User specific code: Your code comes here.
//###########################################################################
    EALLOW;

    AdcaRegs.ADCCTL2.bit.PRESCALE = 6; //set ADCCLK divider to /4
    AdcaRegs.ADCCTL1.bit.ADCPWDNZ = 1; //power up the ADC
    AdcaRegs.ADCCTL1.bit.INTPULSEPOS = 1; //Set interrupt pulse positions to late
    AdcaRegs.ADCCTL2.bit.RESOLUTION = 0; // 12-bit resolution
    AdcaRegs.ADCCTL2.bit.SIGNALMODE = 0; // Single-ended (12-bit mode only)
    DELAY_US(1000); //have to delay at least 500 microseconds before using ADC

    AdcaRegs.ADCSOC0CTL.bit.CHSEL = 0; //SOC0 will convert pin ADCINA0
    AdcaRegs.ADCSOC0CTL.bit.ACQPS = 39; //0.2 micro seconds for sampling window (40 x 5ns = 0.2 micro secs)
    AdcaRegs.ADCSOC0CTL.bit.TRIGSEL = 0x01; //trigger on CPU Timer 0

    CpuTimer0Regs.PRD.all = 10000 - 1;//Load period value. 20 kHz sampling (50 micro seconds period)
    CpuTimer0Regs.TPR.bit.TDDR = 0;//Set the prescale value for the timer as 1.
    CpuTimer0Regs.TCR.bit.TSS = 1;//Stop the timer.
    CpuTimer0Regs.TCR.bit.TRB = 1;//Reload the timer.
    CpuTimer0Regs.TCR.bit.TIE = 1;//Enable the Timer0 interrupt in the peripheral level.
    CpuTimer0Regs.TCR.bit.TSS = 0;//Start the timer.

    AdcaRegs.ADCINTSEL1N2.bit.INT1SEL = 0; //EOC0 will set INT1 flag
    AdcaRegs.ADCINTSEL1N2.bit.INT1CONT = 1; //interrupts will be generated
     //whether the ADCINTFLG is
     //cleared or not
    AdcaRegs.ADCINTSEL1N2.bit.INT1E = 1; //enable INT1 flag

//Redirect the address of the ISR:
    PieVectTable.ADCA1_INT = &adcint1_isr;

    PieCtrlRegs.PIECTRL.bit.ENPIE = 1; // Enable the PIE block
    PieCtrlRegs.PIEIER1.bit.INTx1 = 1; // Enable PIE Group 1 INT1 ADCA1

    IER |= M_INT1;//Enable CPU INT1 includes Xint1
    EINT;//Enable global interrupt mask INTM.
    ERTM;
    EDIS;


    for (;;)
    {

    }
}

//######################   End of main code #######################


//#################### Interrupt Service Routines #################

interrupt void adcint1_isr(void)
{
    static Uint16 *AdcBufPtr = AdcBuf;
    *AdcBufPtr++ = AdcaResultRegs.ADCRESULT0;
    // Brute Force the circular buffer
    if (AdcBufPtr == (AdcBuf + ADC_BUF_LEN))
    {
        AdcBufPtr = AdcBuf;
    }
    //Result = AdcaResultRegs.ADCRESULT0;
    GpioDataRegs.GPBTOGGLE.bit.GPIO32 = 1;
    PieCtrlRegs.PIEACK.all = PIEACK_GROUP1;
}