#include "DSP2833x_Device.h" // DSP2833x Headerfile Include File
#include "DSP2833x_Examples.h" // DSP2833x Examples Include File
// Determine when the shift to right justify the data takes place
// Only one of these should be defined as 1.
// The other two should be defined as 0.
#define POST_SHIFT 0 // Shift results after the entire sample table is full
#define INLINE_SHIFT 1 // Shift results as the data is taken from the results regsiter
#define NO_SHIFT 0 // Do not shift the results
// 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/1 = 25.5MHz/(1) = 25.0 MHz
#define ADC_SHCLK 0x1 // S/H width in ADC module periods = 2 ADC cycle
#define AVG 1000 // Average sample limit
#define ZOFFSET 0x00 // Average Zero offset
#define BUF_SIZE 1024 // Sample buffer size
// Global variable for this example
Uint16 SampleTable[BUF_SIZE];
Uint16 SampleTable1[BUF_SIZE];
Uint16 AD0[64];
main()
{
Uint16 i;
Uint16 j,k;
Uint16 array_index;
InitSysCtrl();
EALLOW;
SysCtrlRegs.HISPCP.all = ADC_MODCLK; // HSPCLK = SYSCLKOUT/ADC_MODCLK
EDIS;
EALLOW;
GpioCtrlRegs.GPBMUX1.bit.GPIO34 = 0; // GPIO pin
GpioCtrlRegs.GPBDIR.bit.GPIO34 = 1; // Output pin
EDIS;
DINT;
InitPieCtrl();
// Disable CPU interrupts and clear all CPU interrupt flags:
IER = 0x0000;
IFR = 0x0000;
InitPieVectTable();
InitAdc(); // For this example, init the ADC
// Specific ADC setup for this example:
AdcRegs.ADCTRL1.bit.ACQ_PS = ADC_SHCLK; // Sequential mode: Sample rate = 1/[(2+ACQ_PS)*ADC clock in ns]
// = 1/(3*40ns) =8.3MHz (for 150 MHz SYSCLKOUT)
// = 1/(3*80ns) =4.17MHz (for 100 MHz SYSCLKOUT)
// If Simultaneous mode enabled: Sample rate = 1/[(3+ACQ_PS)*ADC clock in ns]
AdcRegs.ADCTRL3.bit.ADCCLKPS = ADC_CKPS;
AdcRegs.ADCTRL1.bit.SEQ_CASC = 1; // 1 Cascaded mode
AdcRegs.ADCCHSELSEQ1.bit.CONV00 = 0x1;
AdcRegs.ADCTRL1.bit.CONT_RUN = 1; // Setup continuous run
AdcRegs.ADCTRL1.bit.SEQ_OVRD = 1; // Enable Sequencer override feature
AdcRegs.ADCCHSELSEQ1.all = 0x0; // Initialize all ADC channel selects to A0
AdcRegs.ADCCHSELSEQ2.all = 0x0;
AdcRegs.ADCCHSELSEQ3.all = 0x0;
AdcRegs.ADCCHSELSEQ4.all = 0x0;
AdcRegs.ADCMAXCONV.bit.MAX_CONV1 = 0x1; // convert and store in 8 results registers
// Clear SampleTable
for (i=0; i<BUF_SIZE; i++)
{
SampleTable = 0;
SampleTable1 = 0;
}
for(i=0;i<64;i++)
AD0=0;
// Start SEQ1
AdcRegs.ADCTRL2.all = 0x2000;
for(;;)
{
// Take ADC data and log them in SampleTable array
array_index = 0;
for (i=0; i<(BUF_SIZE); i++)
{
while (AdcRegs.ADCST.bit.INT_SEQ1== 0){}
GpioDataRegs.GPBSET.bit.GPIO34 = 1; // Set GPIO34 for monitoring -optional
AdcRegs.ADCST.bit.INT_SEQ1_CLR = 1;
SampleTable[array_index++]= ( (AdcRegs.ADCRESULT0)>>4);
for(j=0;j<100;j++)
k++;
GpioDataRegs.GPBCLEAR.bit.GPIO34 = 1; // Clear GPIO34 for monitoring -optional
}
}
}
这是片子里面的例子程序，非常简单的一个AD转换（说来惭愧啊），红颜色的是我弄不懂的地方，主要就是下面几个问题：
1、SampleTable1数组是做什么的用的，程序里面也没有用到，初始化的时候还将它设位0！！
2、同样AD0也没有用到，这个数组又是怎么用的啊？
3、SampleTable[array_index++]用来存储转换的结果，那么一次AD转换完成后，里面的数据是通过什么方式移走的？还是重新将里面的数据覆盖呢？
4、最疑惑的一个地方， AdcRegs.ADCMAXCONV.bit.MAX_CONV1 = 0x1; // convert and store in 8 results registers，这句话，它将MAX_CONV1设为1，注释又说将结果存在8个结果寄存器中（不应该是MAX_CONV1+1=2个吗？）另外，在程序开始，选择了级联，连续运行，以及override方式，那么转换过程中结果寄存器到底是怎样应用的呢？几个转换后一次中断？这些看说明说的时候挺明白，现在晕晕的！
问题有点多，也有点啰嗦了，还望高手们能耐心开完，指导指导我。
看不懂的时候，真是着急啊
再此，先诚心谢过了。 |
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