实验四FIR滤波器实验

1、一、实验内谷1掌握TMS320C54XDSPLIB函数库中fir函数的使用方法。2、学习并掌握5402DSP片上外设DMA的结构与配置。3、使用DMA数据传输方式在C语言下实现直接型的FIR滤波器二、实验内容1使用查询方式设计一个fir低通滤波器，通带频率为2400Hz。Fpass=2400,fstop=3000,fs=16000-ftlD|怖比斫费if8MagrituRm勺punmmriJBFr-qijflnirYjltllji#inelude#inelude#inelude#inelude#inelude#ineludevoiddelay(s16period);HANDLEhHandset

2、;s16data;/*Createspecificdatasectionforcoeffiecients*/#pragmaDATA_SECTION(coeffs,coefficients);/*LowPassFilter*/shortcoeffs16=2810,985,-906,-2112,-1653,2005,6878,10556,10556,6878,2005,-1653,-2112,-906,985,2810;#pragmaDATA_SECTION(delaybuff,delay);shortdelaybuff16=0;short*delayptr=&(delaybuff0);short

3、inp_buffer1;shortout_buffer1;short*inp_ptr=inp_buffer;short*out_ptr=out_buffer;voidmain()s16cnt=2;if(brd_init(100)return;/*blinktheledsacoupletimes*/while(cnt-)brd_led_toggle(BRD_LED0);/*brd_delay_msec(1000);*/delay(1000);brd_led_toggle(BRD_LED1);/*brd_delay_msec(1000);*/delay(1000);brd_led_toggle(B

4、RD_LED2);/*brd_delay_msec(1000);*/delay(1000);/*OpenHandsetCodec*/*Acquirehandle/*DACin15-bit/*ADCin15-bit/*6dBgainon/*-6dBgainon/*16KHzsamplingratehHandset=codec_open(HANDSET_CODEC);tocodec*/*Setcodecparameters*/codec_dac_mode(hHandset,CODEC_DAC_15BIT);mode*/codec_adc_mode(hHandset,CODEC_ADC_15BIT)

5、;mode*/codec_ain_gain(hHandset,CODEC_AIN_6dB);analoginputtoADC*/codec_aout_gain(hHandset,CODEC_AOUT_MINUS_6dB);analogoutputfromDAC*/codec_sample_rate(hHandset,SR_16000);*/*Pollinganddigitalloopback*/while(1)/*Waitforsamplefromhandset*/while(!MCBSP_RRDY(HANDSET_CODEC);/*Readsamplefromandwritebacktoha

6、ndsetcodec*/inp_buffer0=*(volatileu16*)DRR1_ADDR(HANDSET_CODEC);/*数据处理开始*/fir计算fir(inp_ptr,coeffs,out_ptr,&delayptr,16,1);data=out_buffer0&0xfffe;/*数据处理结束*/*(volatileu16*)DXR1_ADDR(HANDSET_CODEC)=data;voiddelay(s16period)inti,j;for(i=0;iperiod;i+)for(j=0;j1;j+);2. 使用DMA方式设计FIR低通滤波器，通带截频为4000Hz。从5402

7、DSK板的MIC端口输入频率为3000Hz和5000Hz正弦信号的叠加信号，使用示波器在SPEAKERS口观察输出信号波形。Fpass=4000,fstop=5000,fs=16000-I/lwrirlluclfr(dBFr|UfiC(kht)#include#include#include#include#includevoiddelay(s16period);externvoidDMAC2ISR();HANDLEhHandset;unsignedintdmsefc,dmmcr,dmctr,src_addr,dst_addr;unsignedintdmpre,dmsrcp,dmdstp,dm

8、idx0,dmidx1,dmfri0,dmfri1,dmgsa,dmgda,dmgcr,dmgfr;/*Createspecificdatasectionforbuffer(symbol,section_name)*/#pragmaDATA_SECTION(buffer,audio_buffer);intbuffer0x500;/*Createspecificdatasectionforcoeffiecients*/#pragmaDATA_SECTION(coeffs,coefficients);/*LowPassFilter*/intcoeffs16=560,-1842,-686,1948,

9、-282,-3838,3221,16103,16103,3221,-3838,-282,1948,-686,-1842,560;#pragmaDATA_SECTION(delaybuff,delay);intdelaybuff16=0;/*declareandinitializetwovariablesforDMACISRs*/intframe=0;intflag=0;inttemp;intcurrbuff=0;/*delayptrholdstheaddressofthestartofthedelaybuffer*/int*delayptr1=&(delaybuff0);voidmain()s

10、16cnt=1;/*ThesearetheitemsthatBIOSwillsetwhenweuseit*/BSCR=0x8806;XPC=0;PMST=0xA0;brd_set_cpu_freq(50);TIMER_HALT(0);brd_set_wait_states(7,7,9);TIMER_RESET(0);if(brd_init_bios()return;/*Acquirehandleto/*OpenHandsetCodec*/hHandset=codec_open(HANDSET_CODEC);codec*/*Setcodecparameters*/*DACin15-bitmode

11、/*DACin15-bitmode/*ADCin15-bitmode/*6dBgainonanalog/*-6dBgainonanalog/*16KHzsamplingrate*/codec_dac_mode(hHandset,CODEC_DAC_15BIT);*/codec_adc_mode(hHandset,CODEC_ADC_15BIT);*/codec_ain_gain(hHandset,CODEC_AIN_6dB);inputtoADC*/codec_aout_gain(hHandset,CODEC_AOUT_MINUS_6dB);outputfromDAC*/codec_sampl

12、e_rate(hHandset,SR_16000);/*ClearIFR*/INTR_CLR_FLAG(DMAC2);/*ResetallDMAchannels*/dma_reset_all();/*InitializeDMAchannel2*/dmsefc=(DSYNC_REVT112);dmmcr=(AUTOINIT_ENABLE15)|(DINM_ENABLE14)|(IMOD_HALFBLOCK13)|(CTMOD_DEC12)|(INDEXMODE_NOMOD8)|(SPACE_DATA6)|(INDEXMODE_INC2)|(SPACE_DATA);dmctr=0xFF;src_a

13、ddr=DRR1_ADDR(HANDSET_CODEC);dst_addr=(unsignedint)&buffer;dma_init(DMA_CH2,dmsefc,dmmcr,dmctr,SPACE_DATA,src_addr,SPACE_DATA,dst_addr);/*Setnumberofframesforchannel2*/DMA_FRAMECOUNT(DMA_CH2,2);/*SetupglobalautoinitregistersforDMACH2Input*/dmgsa=src_addr;dmgda=dst_addr;dmgcr=0xFF;dmgfr=2;/*Setupglob

14、alpriorityandenablecontrolregisterforCh2*/dmpre=(HIGH_PRIORITY10)|(INTSEL_016);dmsrcp=SPACE_DATA;dmdstp=SPACE_DATA;dmidx0=0;dmidx1=0;dmfri0=0;dmfri1=0;dma_global_init(dmpre,dmsrcp,dmdstp,dmidx0,dmidx1,dmfri0,dmfri1,dmgsa,dmgda,dmgcr,dmgfr);/*Enablechannel2*/DMA_ENABLE(DMA_CH2);/*primetheserialportto

15、begininputbufferstream*/temp=*(volatileu16*)DRR1_ADDR(HANDSET_CODEC);/*EnableDMAC2interrupt*/INTR_ENABLE(DMAC2);/*EnableGlobalInterrupts*/INTR_GLOBAL_ENABLE;/*EndlessloopwaitingforDMAC2interrupt*/for(;);voiddelay(s16period)inti,j;for(i=0;iperiod;i+)for(j=0;j1;j+);三、思考题1、滤波器设计中为什么要设有延迟缓冲存储器delaybuff？其大小有什么限制？答：在连续的数据块计算时，延迟缓冲区保存着后一次计算所需要的前一次的输出数据。这个缓冲存储区的起点必须位于Kbit的边界处，即起始地址的最低K=log2nh个有效位必须为零。2、使用查询方式和DMA中断方式设计FIR滤波器时，允许DSP用于数字信号处理程序的最大时间分别是多少？答：查询方式允许DSP用于数字信号处理程序的最大时间是Ts,而DMA中断方式设计FIR滤波器时允许用于数字信号处理程序的最大时间是256Ts。3、如何设置CCS将滤波结果保存在外部数据文件*.dat中？答