example_281x_fft.c

fft变换源程序

/*
;**************************************************************
;*				   北京达盛科技有限公司
;*                    研    发    部
;*
;*             	http://www.techshine.com
;*************************************************************/
/*----------------------- 文件信息 ----------------------------                                      
;*  
;* 文件名称 : Example_DSP281x_FFT.c 	
;* 适用平台 : DSP专家3实验箱
;* CPU类型  : DSP TMS320F2812 
;* 软件环境 : CCS2.20 (2000系列)
;* 试验接线 : 1、F2812CPU板的JUMP1的2和3脚短接，JUMP2的1和2脚短接；
;*            2、底板的开关K9拨到右侧，选择CPU2
;*            3、具体连线见说明书.
;* 试验现象 : 设置好CCS的环境，打开本工程，编译、下载、运行。
;*            利用变量观察窗口观察分析结果。
;* 地址译码说明：基地址：0x80000
*/    
//------------------头文件-------------------------------------//
#include <math.h>
#include "DSP281x_Device.h"     // DSP281x Headerfile Include File
#include "DSP281x_Examples.h"   // DSP281x Examples Include File

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

// Global variables used in this example:
Uint16 ConversionCount;
Uint16 px[128];
Uint16 pz[128];

void kfft(pr,pi,n,k,fr,fi,l,il)
     Uint16 n,k,l,il;
     double pr[],pi[],fr[],fi[];
  { int it,m,is,i,j,nv,l0;
    double p,q,s,vr,vi,poddr,poddi;
    for (it=0; it<=n-1; it++)
      { m=it; is=0;
        for (i=0; i<=k-1; i++)
          { j=m/2; is=2*is+(m-2*j); m=j;}
        fr[it]=pr[is]; fi[it]=pi[is];
      }
    pr[0]=1.0; pi[0]=0.0;
    p=6.283185306/(1.0*n);
    pr[1]=cos(p); pi[1]=-sin(p);
    if (l!=0) pi[1]=-pi[1];
    for (i=2; i<=n-1; i++)
      { p=pr[i-1]*pr[1]; q=pi[i-1]*pi[1];
        s=(pr[i-1]+pi[i-1])*(pr[1]+pi[1]);
        pr[i]=p-q; pi[i]=s-p-q;
      }
    for (it=0; it<=n-2; it=it+2)
      { vr=fr[it]; vi=fi[it];
        fr[it]=vr+fr[it+1]; fi[it]=vi+fi[it+1];
        fr[it+1]=vr-fr[it+1]; fi[it+1]=vi-fi[it+1];
      }
    m=n/2; nv=2;
    for (l0=k-2; l0>=0; l0--)
      { m=m/2; nv=2*nv;
        for (it=0; it<=(m-1)*nv; it=it+nv)
          for (j=0; j<=(nv/2)-1; j++)
            { p=pr[m*j]*fr[it+j+nv/2];
              q=pi[m*j]*fi[it+j+nv/2];
              s=pr[m*j]+pi[m*j];
              s=s*(fr[it+j+nv/2]+fi[it+j+nv/2]);
              poddr=p-q; poddi=s-p-q;
              fr[it+j+nv/2]=fr[it+j]-poddr;
              fi[it+j+nv/2]=fi[it+j]-poddi;
              fr[it+j]=fr[it+j]+poddr;
              fi[it+j]=fi[it+j]+poddi;
            }
      }
    if (l!=0)
      for (i=0; i<=n-1; i++)
        { fr[i]=fr[i]/(1.0*n);
          fi[i]=fi[i]/(1.0*n);
        }
    if (il!=0)
      for (i=0; i<=n-1; i++)
        { pr[i]=sqrt(fr[i]*fr[i]+fi[i]*fi[i]);
          if (fabs(fr[i])<0.000001*fabs(fi[i]))
            { if ((fi[i]*fr[i])>0) pi[i]=90.0;
              else pi[i]=-90.0;
            }
          else
            pi[i]=atan(fi[i]/fr[i])*360.0/6.283185306;
        }
   return;
   }

void main(void) 
{
   int i,n,k=0;		
   double x[128],pr[128],pi[128],fr[128],fi[128],mo[128];
   int xm,zm;
   n=128;  
// PLL, WatchDog, enable Peripheral Clocks
// This example function is found in the DSP281x_SysCtrl.c file.
   InitSysCtrl();

// For this example, set HSPCLK to SYSCLKOUT / 6 (25Mhz assuming 150Mhz SYSCLKOUT)
   EALLOW;
   SysCtrlRegs.HISPCP.all = 0x3;  // HSPCLK = SYSCLKOUT/6
   EDIS;
   

// Disable CPU interrupts 
   DINT;

// Initialize the PIE control registers to their default state.
   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();
     
// 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

   InitAdc();  // For this example, init the ADC

// 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

   ConversionCount = 0;
    
// Configure ADC
   AdcRegs.ADCTRL1.bit.SEQ_CASC = 1;  
   AdcRegs.ADCMAXCONV.all = 0x0000;       // Setup 2 conv's on SEQ1
   AdcRegs.ADCCHSELSEQ1.bit.CONV00 = 0x4; // Setup ADCINA4 as 1st SEQ1 conv.
   AdcRegs.ADCTRL2.bit.EVA_SOC_SEQ1 = 1;  // Enable EVASOC to start SEQ1
   AdcRegs.ADCTRL2.bit.INT_ENA_SEQ1 = 1;  // Enable SEQ1 interrupt (every EOS)

// Configure EVA
// Assumes EVA Clock is already enabled in InitSysCtrl();
   EvaRegs.T1CMPR = 0x0380;               // Setup T1 compare value
   EvaRegs.T1PR = 0x07FF;                 // Setup period register
   EvaRegs.GPTCONA.bit.T1TOADC = 1;       // Enable EVASOC in EVA
   EvaRegs.T1CON.all = 0x1042;            // Enable timer 1 compare (upcount mode)

// Wait for ADC interrupt
   for (;;)
	{	
		   		
			for (i=0; i<=n-1; i++)
			{
				xm=px[i];
				x[i]=xm/1023.0;
				pr[i]=x[i];
				pi[i]=0;
			}		
    	
			kfft(pr,pi,128,7,fr,fi,0,1);
			
			for (i=0;i<=n-1;i++)
	  		{
	       		mo[i] = sqrt(fr[i]*fr[i]+fi[i]*fi[i]);
		   		zm = (int)(mo[i]*1000.0);
		   		pz[i] = zm;
		  	}  	
		        pz[0]=0;
		          k++;  		//加断点，观察波形  	
      }
                       
}


interrupt void  adc_isr(void)
{

  px[ConversionCount] = AdcRegs.ADCRESULT0 >>4;

  if(ConversionCount == 128) 
  {
     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;
}