tms320f28335发现采样频率总是不对啊。求助求助。-TI中文支持网

用了官网的ADCsoc.c程序，稍微改了一下参数，设置了一个标志位，检测GPIO32发现每20us翻转一次。但是设置时间不是10us么？SOCASEL改成2，PRD触发，现象一样。ADC采样窗口宽度好像在程序里也没有设置啊？即使是采样窗口宽度，也不会影响到PWM触发吧？菜鸟小白，求助各位经验者，大神，工程师。不胜感激。

#include "DSP28x_Project.h" // Device Headerfile and Examples Include File

// Prototype statements for functions found within this file.
interrupt void adc_isr(void);
void Gpio_select(void);

void Gpio_example3(void);

// Global variables used in this example:
Uint16 LoopCount;
Uint16 ConversionCount;
Uint16 Voltage1[30];
Uint16 Voltage2[30];

main()
{

// Step 1. Initialize System Control:
// PLL, WatchDog, enable Peripheral Clocks
// This example function is found in the DSP2833x_SysCtrl.c file.
InitSysCtrl();
Gpio_select();

EALLOW;
#if (CPU_FRQ_150MHZ) // Default – 150 MHz SYSCLKOUT
#define ADC_MODCLK 0x3 // HSPCLK = SYSCLKOUT/2*ADC_MODCLK2 = 150/(2*3) = 25.0 MHz
#endif
#if (CPU_FRQ_100MHZ)
#define ADC_MODCLK 0x2 // HSPCLK = SYSCLKOUT/2*ADC_MODCLK2 = 100/(2*2) = 25.0 MHz
#endif
EDIS;

// Define ADCCLK clock frequency ( less than or equal to 25 MHz )
// Assuming InitSysCtrl() has set SYSCLKOUT to 150 MHz
EALLOW;
SysCtrlRegs.HISPCP.all = ADC_MODCLK;
EDIS;

// Step 2. Initialize GPIO:
// This example function is found in the DSP2833x_Gpio.c file and
// illustrates how to set the GPIO to it's default state.
// InitGpio(); // Skipped for this example

// Step 3. 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 DSP2833x_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 DSP2833x_DefaultIsr.c.
// This function is found in DSP2833x_PieVect.c.
InitPieVectTable();

// Interrupts that are used in this example are re-mapped to
// ISR functions found within this file.
EALLOW; // This is needed to write to EALLOW protected register
PieVectTable.ADCINT = &adc_isr;
EDIS; // This is needed to disable write to EALLOW protected registers

// Step 4. Initialize all the Device Peripherals:
// This function is found in DSP2833x_InitPeripherals.c
// InitPeripherals(); // Not required for this example
InitAdc(); // For this example, init the ADC

// Step 5. User specific code, enable interrupts:

// Enable ADCINT in PIE
PieCtrlRegs.PIEIER1.bit.INTx6 = 1;
IER |= M_INT1; // Enable CPU Interrupt 1
EINT; // Enable Global interrupt INTM
ERTM; // Enable Global realtime interrupt DBGM

LoopCount = 0;
ConversionCount = 0;

GpioDataRegs.GPBSET.all =0x00000000;
GpioDataRegs.GPBCLEAR.all =0x00000001;

// Configure ADC
AdcRegs.ADCMAXCONV.all = 0x0000; // Setup 2 conv's on SEQ1
AdcRegs.ADCCHSELSEQ1.bit.CONV00 = 0x0; // Setup ADCINA3 as 1st SEQ1 conv.
//AdcRegs.ADCCHSELSEQ1.bit.CONV01 = 0x2; // Setup ADCINA2 as 2nd SEQ1 conv.
AdcRegs.ADCTRL2.bit.EPWM_SOCA_SEQ1 = 1;// Enable SOCA from ePWM to start SEQ1
AdcRegs.ADCTRL2.bit.INT_ENA_SEQ1 = 1; // Enable SEQ1 interrupt (every EOS)

// Assumes ePWM1 clock is already enabled in InitSysCtrl();
EPwm2Regs.ETSEL.bit.SOCAEN = 1; // Enable SOC on A group
EPwm2Regs.ETSEL.bit.SOCASEL = 4; // Select SOC from from CPMA on upcount
EPwm2Regs.ETPS.bit.SOCAPRD = 1; // Generate pulse on 1st event
EPwm2Regs.CMPA.half.CMPA = 750; // Set compare A value
EPwm2Regs.TBPRD = 1500; // Set period for ePWM1
EPwm2Regs.TBCTL.bit.CTRMODE = 0; // count up and start

// Wait for ADC interrupt
for(;;)
{
LoopCount++;
}

}

interrupt void adc_isr(void)
{

Voltage1[ConversionCount] = AdcRegs.ADCRESULT0 >>4;
// Voltage2[ConversionCount] = AdcRegs.ADCRESULT1 >>4;
GpioDataRegs.GPBTOGGLE.all =0x00000001;
// If 40 conversions have been logged, start over
if(ConversionCount == 29)
{
ConversionCount = 0;
}
else ConversionCount++;

// Reinitialize for next ADC sequence
AdcRegs.ADCTRL2.bit.RST_SEQ1 = 1; // Reset SEQ1
AdcRegs.ADCST.bit.INT_SEQ1_CLR = 1; // Clear INT SEQ1 bit
PieCtrlRegs.PIEACK.all = PIEACK_GROUP1; // Acknowledge interrupt to PIE

return;
}

void Gpio_select(void)
{

EALLOW;
GpioCtrlRegs.GPBMUX1.all = 0x00000000; // All GPIO
GpioCtrlRegs.GPBMUX2.all = 0x00000000; // All GPIO
GpioCtrlRegs.GPBDIR.all = 0x0000000F; // All outputs
EDIS;

}

tianqing li：

感觉应该是采样保持器最小是2个周期吧。

ACQ_PS[3:0]

acquisition window size. This bit field controls the width of SOC pulse, which, in turn,determines for what time duration the sampling switch is closed. The width of SOC pulseis ADCTRL1[11:8] + 1 times the ADCLK period

对上面的话，我有了误解。spru812a的26页，设置ACQ_PS=15，要对前面的时钟除以17才行。