Ashwin Athani / Mbed 2 deprecated mX_audio

mX mbed BaseBoard audio

Dependencies:   mbed

main.cpp@0:6c621d41bf07, 2010-12-08 (annotated)

Committer:
ashwin_athani
Date:
Wed Dec 08 06:21:06 2010 +0000
Revision:
0:6c621d41bf07

        

        
Who changed what in which revision?

        

            
                
UserRevisionLine numberNew contents of line

            
            


ashwin_athani

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#include "mbed.h"





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#include "SDFileSystem.h"





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AnalogOut DACout(p18);





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DigitalOut led1(LED1);





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DigitalOut led2(LED2);





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DigitalOut led3(LED3);





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DigitalOut led4(p8);





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DigitalOut digout(LED4);





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Ticker tick;





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//SDFileSystem sd(p11, p12, p13, p14, "sd");





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SDFileSystem sd(p5, p6, p7, p8, "sd"); // NGX mbed base board





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#define SAMPLE_FREQ 40000





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#define BUF_SIZE (SAMPLE_FREQ/10)





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#define SLICE_BUF_SIZE 1





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void dac_out(void);





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void play_wave(char *);





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void cleanup(char *);





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void fill_adc_buf(short *, unsigned);





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void swapword(unsigned *);





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// a FIFO for the DAC





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short DAC_fifo[256];





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short DAC_wptr;





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short DAC_rptr;





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short DAC_on;





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typedef struct uFMT_STRUCT {





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  short comp_code;





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  short num_channels;





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  unsigned sample_rate;





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  unsigned avg_Bps;





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  short block_align;





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  short sig_bps;





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} FMT_STRUCT;





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int main() {





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  led1=0; wait(.5); led1=1; wait(.5); led1=0;





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  printf("Hello, world!\n");





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  play_wave("/sd/forest.wav");





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  printf("Back from forest\n");





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  printf("Goodbye, world!\n");





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  led1=1; wait(.5); led1=0; wait(.5); led1=1;





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}





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void play_wave(char *wavname)





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{





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        unsigned chunk_id,chunk_size,channel;





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//        unsigned *data_wptr,data,samp_int,i;





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        unsigned data,samp_int,i;





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        short dac_data;





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        char *slice_buf;





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        short *data_sptr;





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//        char *data_bptr;





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        FMT_STRUCT wav_format;





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        FILE *wavfile;





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        long slice,num_slices;





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  DAC_wptr=0;





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  DAC_rptr=0;





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  for (i=0;i<256;i+=2) {





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    DAC_fifo[i]=0;





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    DAC_fifo[i+1]=3000;





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  }





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  DAC_wptr=4;





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  DAC_on=0;





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  led1=led2=led3=led4=0;





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  printf("Playing wave file '%s'\n",wavname);





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  wavfile=fopen(wavname,"rb");





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  if (!wavfile) {





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    printf("Unable to open wav file '%s'\n",wavname);





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    exit(1);





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  }





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  fread(&chunk_id,4,1,wavfile);





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  fread(&chunk_size,4,1,wavfile);





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  while (!feof(wavfile)) {





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    printf("Read chunk ID 0x%x, size 0x%x\n",chunk_id,chunk_size);





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    switch (chunk_id) {





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      case 0x46464952:





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        fread(&data,4,1,wavfile);





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        printf("RIFF chunk\n");





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        printf("  chunk size %d (0x%x)\n",chunk_size,chunk_size);





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        printf("  RIFF type 0x%x\n",data);





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        break;





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      case 0x20746d66:





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        fread(&wav_format,sizeof(wav_format),1,wavfile);





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        printf("FORMAT chunk\n");





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        printf("  chunk size %d (0x%x)\n",chunk_size,chunk_size);





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        printf("  compression code %d\n",wav_format.comp_code);





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        printf("  %d channels\n",wav_format.num_channels);





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        printf("  %d samples/sec\n",wav_format.sample_rate);





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        printf("  %d bytes/sec\n",wav_format.avg_Bps);





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        printf("  block align %d\n",wav_format.block_align);





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        printf("  %d bits per sample\n",wav_format.sig_bps);





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        if (chunk_size > sizeof(wav_format))





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          fseek(wavfile,chunk_size-sizeof(wav_format),SEEK_CUR);





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// create a slice buffer large enough to hold multiple slices





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        slice_buf=(char *)malloc(wav_format.block_align*SLICE_BUF_SIZE);





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        if (!slice_buf) {





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          printf("Unable to malloc slice buffer");





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          exit(1);





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        }





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        break;





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      case 0x61746164:





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        slice_buf=(char *)malloc(wav_format.block_align*SLICE_BUF_SIZE);





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        if (!slice_buf) {





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          printf("Unable to malloc slice buffer");





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          exit(1);





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        }        num_slices=chunk_size/wav_format.block_align;





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        printf("DATA chunk\n");





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        printf("  chunk size %d (0x%x)\n",chunk_size,chunk_size);





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        printf("  %d slices\n",num_slices);





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        printf("  Ideal sample interval=%d\n",(unsigned)(1000000.0/wav_format.sample_rate));





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        samp_int=1000000/(wav_format.sample_rate);





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        printf("  programmed interrupt tick interval=%d\n",samp_int);





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// starting up ticker to write samples out -- no printfs until tick.detach is called





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        tick.attach_us(&dac_out, samp_int); 





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        DAC_on=1; 





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        led2=1;





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        for (slice=0;slice<num_slices;slice+=SLICE_BUF_SIZE) {





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          fread(slice_buf,wav_format.block_align*SLICE_BUF_SIZE,1,wavfile);





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          if (feof(wavfile)) {





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            printf("Oops -- not enough slices in the wave file\n");





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            exit(1);





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          }





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          data_sptr=(short *)slice_buf;





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          for (i=0;i<SLICE_BUF_SIZE;i++) {





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            dac_data=0;





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// for a stereo wave file average the two channels.





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            for (channel=0;channel<wav_format.num_channels;channel++) {





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              switch (wav_format.sig_bps) {





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                case 16:





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                  dac_data+=(  ((int)(*data_sptr++)) +32768)>>5;





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                  break;





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              }





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            }





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            dac_data>>=1;





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            DAC_fifo[DAC_wptr]=dac_data;





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            DAC_wptr=(DAC_wptr+1) & 0xff;





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            while (DAC_wptr==DAC_rptr) {





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              led1=1;





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            }





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            led1=0;





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          }





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        }





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        DAC_on=0;





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        led2=0;





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        tick.detach();





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        printf("Ticker detached\n");





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        led3=1;





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        free(slice_buf);





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        break;





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      case 0x5453494c:





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        printf("INFO chunk, size %d\n",chunk_size);





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        fseek(wavfile,chunk_size,SEEK_CUR);





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        break;





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      default:





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        printf("unknown chunk type 0x%x, size %d\n",chunk_id,chunk_size);





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        data=fseek(wavfile,chunk_size,SEEK_CUR);





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        break;





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    }





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    fread(&chunk_id,4,1,wavfile);





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    fread(&chunk_size,4,1,wavfile);





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  }





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  printf("Done with wave file\n");





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  fclose(wavfile);





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  led1=0;





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}





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void dac_out()





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{





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  if (DAC_on) {





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    digout=1;





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    DACout.write_u16(DAC_fifo[DAC_rptr]);





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    DAC_rptr=(DAC_rptr+1) & 0xff;





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    digout=0;





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  }





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}





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