main.cpp

00001 #include "mbed.h"
00002 #include "SDHCFileSystem.h"
00003 #include "TLV320.h"
00004  
00005 TLV320 audio(p9, p10, 52, p5, p6, p7, p8, p29); //TLV320 object
00006 SDFileSystem sd(p11, p12, p13, p14, "sd");      //SD Card object
00007 InterruptIn volumeSet(p17);                     
00008 AnalogIn aIn(p19); 
00009 FILE *infp;                                     //File pointer object
00010 /* Buffers */
00011 int circularBuffer[4096];    
00012 volatile int readPointer = 0;
00013 volatile int theta = 0;
00014 /* Wav file header data, for setting up the transfer protocol */
00015 short channels;
00016 long sampleRate;
00017 short wordWidth;
00018 /* Function to set volume*/
00019 void setVolume(void){
00020     audio.outputVolume(aIn, aIn);                
00021 }
00022 /* Function to read from circular buffer and send data to TLV320 */
00023 void play(void){ 
00024         audio.write(circularBuffer, readPointer, 8);      
00025         //Pointer fun :-)
00026         readPointer += 8;
00027         readPointer &= 0xfff;
00028         theta -= 8;
00029 }
00030 /* Function to load circular buffer from SD Card */
00031 void fillBuffer(void){
00032     while(!feof(infp)){                                         //fill the circular buffer until the end of the file
00033         static volatile int writePointer = 0;
00034         if(theta < 4096){
00035             fread(&circularBuffer[writePointer], 4, 4, infp);   //read 4 integers into the circular buffer at a time
00036             //More pointer fun :D
00037             theta+=4;
00038             writePointer+=4;
00039             writePointer &= 0xfff;
00040         }
00041     }
00042 }
00043 /* main */
00044 int main(){   
00045     infp = fopen("/sd/test.wav", "r");      //open file
00046         if(infp == NULL){                   //make sure it's been opened
00047         perror("Error opening file!");
00048         exit(1);
00049     }
00050     /* Parse wav file header */
00051     fseek(infp, 22, SEEK_SET);                      
00052     fread(&channels, 2, 1, infp);
00053     fseek(infp, 24, SEEK_SET);
00054     fread(&sampleRate, 4, 1, infp);
00055     fseek(infp, 34, SEEK_SET);
00056     fread(&wordWidth, 2, 1, infp);
00057     
00058     volumeSet.rise(&setVolume);             //attach set volume function to digital input
00059     audio.power(0x07);                      //power up TLV apart from analogue input
00060     audio.frequency(sampleRate);            //set sample frequency
00061     audio.format(wordWidth, (2-channels));  //set transfer protocol
00062     audio.attach(&play);                    //attach interrupt handler to send data to TLV320
00063     for(int j = 0; j < 4096; ++j){          //upon interrupt generation
00064         circularBuffer[j] = 0;              //clear circular buffer
00065     }
00066     audio.start(TRANSMIT);                  //interrupt come from the I2STXFIFO only
00067     fillBuffer();                           //continually fill circular buffer
00068 }