Daniel Worrall / Mbed 2 deprecated playback

Use the TLV320 with in-built I2S object to stream audio data from an SD Card and send it to the TLV320 CODEC for audio playback

Dependencies:   I2SSlave mbed TLV320

main.cpp@1:9ea0cc2fa567, 2011-08-05 (annotated)

Committer:
d_worrall
Date:
Fri Aug 05 10:12:21 2011 +0000
Revision:
1:9ea0cc2fa567
Parent:
0:3d6892f6384f 
verison 2.0

Who changed what in which revision?

UserRevisionLine numberNew contents of line
d_worrall 0:3d6892f6384f 1 #include "mbed.h"
d_worrall 0:3d6892f6384f 2 #include "SDHCFileSystem.h"
d_worrall 0:3d6892f6384f 3 #include "TLV320.h"
d_worrall 0:3d6892f6384f 4
d_worrall 0:3d6892f6384f 5 TLV320 audio(p9, p10, 52, p5, p6, p7, p8, p29); //TLV320 object
d_worrall 0:3d6892f6384f 6 SDFileSystem sd(p11, p12, p13, p14, "sd"); //SD Card object
d_worrall 0:3d6892f6384f 7 InterruptIn volumeSet(p17);
d_worrall 0:3d6892f6384f 8 AnalogIn aIn(p19);
d_worrall 0:3d6892f6384f 9 FILE *infp; //File pointer object
d_worrall 0:3d6892f6384f 10 /* Buffers */
d_worrall 0:3d6892f6384f 11 int circularBuffer[4096];
d_worrall 0:3d6892f6384f 12 volatile int readPointer = 0;
d_worrall 0:3d6892f6384f 13 volatile int theta = 0;
d_worrall 0:3d6892f6384f 14 /* Wav file header data, for setting up the transfer protocol */
d_worrall 0:3d6892f6384f 15 short channels;
d_worrall 0:3d6892f6384f 16 long sampleRate;
d_worrall 0:3d6892f6384f 17 short wordWidth;
d_worrall 0:3d6892f6384f 18 /* Function to set volume*/
d_worrall 0:3d6892f6384f 19 void setVolume(void){
d_worrall 0:3d6892f6384f 20 audio.outputVolume(aIn, aIn);
d_worrall 0:3d6892f6384f 21 }
d_worrall 0:3d6892f6384f 22 /* Function to read from circular buffer and send data to TLV320 */
d_worrall 0:3d6892f6384f 23 void play(void){
d_worrall 0:3d6892f6384f 24 audio.write(circularBuffer, readPointer, 8);
d_worrall 0:3d6892f6384f 25 //Pointer fun :-)
d_worrall 0:3d6892f6384f 26 readPointer += 8;
d_worrall 0:3d6892f6384f 27 readPointer &= 0xfff;
d_worrall 0:3d6892f6384f 28 theta -= 8;
d_worrall 0:3d6892f6384f 29 }
d_worrall 0:3d6892f6384f 30 /* Function to load circular buffer from SD Card */
d_worrall 0:3d6892f6384f 31 void fillBuffer(void){
d_worrall 0:3d6892f6384f 32 while(!feof(infp)){ //fill the circular buffer until the end of the file
d_worrall 0:3d6892f6384f 33 static volatile int writePointer = 0;
d_worrall 0:3d6892f6384f 34 if(theta < 4096){
d_worrall 0:3d6892f6384f 35 fread(&circularBuffer[writePointer], 4, 4, infp); //read 4 integers into the circular buffer at a time
d_worrall 0:3d6892f6384f 36 //More pointer fun :D
d_worrall 0:3d6892f6384f 37 theta+=4;
d_worrall 0:3d6892f6384f 38 writePointer+=4;
d_worrall 0:3d6892f6384f 39 writePointer &= 0xfff;
d_worrall 0:3d6892f6384f 40 }
d_worrall 0:3d6892f6384f 41 }
d_worrall 0:3d6892f6384f 42 }
d_worrall 0:3d6892f6384f 43 /* main */
d_worrall 0:3d6892f6384f 44 int main(){
d_worrall 0:3d6892f6384f 45 infp = fopen("/sd/test.wav", "r"); //open file
d_worrall 0:3d6892f6384f 46 if(infp == NULL){ //make sure it's been opened
d_worrall 0:3d6892f6384f 47 perror("Error opening file!");
d_worrall 0:3d6892f6384f 48 exit(1);
d_worrall 0:3d6892f6384f 49 }
d_worrall 0:3d6892f6384f 50 /* Parse wav file header */
d_worrall 0:3d6892f6384f 51 fseek(infp, 22, SEEK_SET);
d_worrall 0:3d6892f6384f 52 fread(&channels, 2, 1, infp);
d_worrall 0:3d6892f6384f 53 fseek(infp, 24, SEEK_SET);
d_worrall 0:3d6892f6384f 54 fread(&sampleRate, 4, 1, infp);
d_worrall 0:3d6892f6384f 55 fseek(infp, 34, SEEK_SET);
d_worrall 0:3d6892f6384f 56 fread(&wordWidth, 2, 1, infp);
d_worrall 0:3d6892f6384f 57
d_worrall 0:3d6892f6384f 58 volumeSet.rise(&setVolume); //attach set volume function to digital input
d_worrall 0:3d6892f6384f 59 audio.power(0x07); //power up TLV apart from analogue input
d_worrall 0:3d6892f6384f 60 audio.frequency(sampleRate); //set sample frequency
d_worrall 0:3d6892f6384f 61 audio.format(wordWidth, (2-channels)); //set transfer protocol
d_worrall 0:3d6892f6384f 62 audio.attach(&play); //attach interrupt handler to send data to TLV320
d_worrall 0:3d6892f6384f 63 for(int j = 0; j < 4096; ++j){ //upon interrupt generation
d_worrall 0:3d6892f6384f 64 circularBuffer[j] = 0; //clear circular buffer
d_worrall 0:3d6892f6384f 65 }
d_worrall 0:3d6892f6384f 66 audio.start(TRANSMIT); //interrupt come from the I2STXFIFO only
d_worrall 0:3d6892f6384f 67 fillBuffer(); //continually fill circular buffer
d_worrall 0:3d6892f6384f 68 }