28335的 ADC 采样率最大能达到多少？是12.5Msps 吗? 我用0.5MHz的 方波信号测试，结果显示一个周期只有10个点，即采样率只达到了5MHz，这是极限速度吗？
还是因为存取的指令时间太长了，有些值没保存下来？ 我的代码如下：
//###########################################################################
//
// FILE: Example_2833xAdcSeqModeTest.c
//
// TITLE: DSP2833x ADC Seq Mode Test.
//
// ASSUMPTIONS:
//
// This program requires the DSP2833x header files.
//
// Make sure the CPU clock speed is properly defined in
// DSP2833x_Examples.h before compiling this example.
//
// Connect the signal to be converted to channel A0.
//
// As supplied, this project is configured for "boot to SARAM"
// operation. The 2833x Boot Mode table is shown below.
// For information on configuring the boot mode of an eZdsp,
// please refer to the documentation included with the eZdsp,
//
// $Boot_Table:
//
// GPIO87 GPIO86 GPIO85 GPIO84
// XA15 XA14 XA13 XA12
// PU PU PU PU
// ==========================================
// 1 1 1 1 Jump to Flash
// 1 1 1 0 SCI-A boot
// 1 1 0 1 SPI-A boot
// 1 1 0 0 I2C-A boot
// 1 0 1 1 eCAN-A boot
// 1 0 1 0 McBSP-A boot
// 1 0 0 1 Jump to XINTF x16
// 1 0 0 0 Jump to XINTF x32
// 0 1 1 1 Jump to OTP
// 0 1 1 0 Parallel GPIO I/O boot
// 0 1 0 1 Parallel XINTF boot
// 0 1 0 0 Jump to SARAM <- "boot to SARAM"
// 0 0 1 1 Branch to check boot mode
// 0 0 1 0 Boot to flash, bypass ADC cal
// 0 0 0 1 Boot to SARAM, bypass ADC cal
// 0 0 0 0 Boot to SCI-A, bypass ADC cal
// Boot_Table_End$
//
// DESCRIPTION:
//
// Channel A0 is converted forever and logged in a buffer (SampleTable)
//
// Open a memory window to SampleTable to observe the buffer
// RUN for a while and stop and see the table contents.
//
// Watch Variables:
// SampleTable - Log of converted values.
//
//###########################################################################
//
// Original source by: S.S.
//
// $TI Release: 2833x/2823x Header Files and Peripheral Examples V133 $
// $Release Date: June 8, 2012 $
//###########################################################################
#include "DSP28x_Project.h" // Device Headerfile and Examples Include File
// ADC start parameters
#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
#define ADC_CKPS 0x0 // ADC module clock = HSPCLK/2*ADC_CKPS = 25.0MHz/(1*2) = 12.5MHz
#define ADC_SHCLK 0x0 //0x0f // S/H width in ADC module periods = 16 ADC clocks
#define AVG 1000 // Average sample limit
#define ZOFFSET 0x00 // Average Zero offset
#define BUF_SIZE 2048 // Sample buffer size
// Global variable for this example
Uint16 SampleTable[BUF_SIZE];
main()
{
Uint16 i;
// Step 1. Initialize System Control:
// PLL, WatchDog, enable Peripheral Clocks
// This example function is found in the DSP2833x_SysCtrl.c file.
InitSysCtrl();
// Specific clock setting for this example:
EALLOW;
SysCtrlRegs.HISPCP.all = ADC_MODCLK; // HSPCLK = SYSCLKOUT/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();
// 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
// Specific ADC setup for this example:
AdcRegs.ADCTRL1.bit.ACQ_PS = ADC_SHCLK;
AdcRegs.ADCTRL3.bit.ADCCLKPS = ADC_CKPS;
AdcRegs.ADCTRL1.bit.SEQ_CASC = 1; // 1 Cascaded mode
AdcRegs.ADCCHSELSEQ1.bit.CONV00 = 0x0;
AdcRegs.ADCTRL1.bit.CONT_RUN = 1; // Setup continuous run
// Step 5. User specific code, enable interrupts:
// Clear SampleTable
for (i=0; i<BUF_SIZE; i++)
{
SampleTable[i] = 0;
}
// Start SEQ1
AdcRegs.ADCTRL2.all = 0x2000;
// Take ADC data and log the in SampleTable array
for(;;)
{
for (i=0; i<AVG; i++)
{
// while (AdcRegs.ADCST.bit.INT_SEQ1== 0) {} // Wait for interrupt
AdcRegs.ADCST.bit.INT_SEQ1_CLR = 1;
SampleTable[i] =((AdcRegs.ADCRESULT0>>4) );
}
while(1);
}
}
//===========================================================================
// No more.
//===========================================================================
