mp3_player.c

基于at89c51单片机的mp3 mp3播放实验资料及代码

#include "AT89C51SND1_REG.H"
#include "MP3_PLAYER.H"
#include "FILE_SYS.H"
#include "MCU_UART.H"


void MP3FsInit(unsigned char NDIV, unsigned int RDIV, unsigned char MPCD, unsigned char AUCD)
{
	PLLNDIV = 0;
	PLLRDIV = 0;
	MP3CLK = 0;
	AUDCLK = 0;
//PLLclk=(OSCclk*(RDIV+1))/(int)(NDIV+1)
	PLLNDIV	= 0x7f&NDIV;           //set NDIV                  
	PLLCON	|= (0x3&RDIV) << 6;    //set RDIV                  
	PLLRDIV	= (0x3ff&RDIV) >> 2;   

//MP3CLK=PLLCLK/(int)(MPCD+1)
	MP3CLK |= MPCD;

//AUDCLK=PLLCLK/(int)(AUCD+1)
	AUDCLK  |= AUCD;             

}

void PllInit(void)
{
	CKCON |= X2;
	PLLCON &= (~PLLRES);  //Enable PLL
	PLLCON |= PLLEN;
}

void MP3Init()
{
	MP3VOR = 0x0a;
	MP3VOL = 0x0a;
	MP3BAS = 0x10;
	MP3MED = 0x10;
	MP3TRE = 0x10;
	MP3CON &= (~MSKREQ);            //Clear to allow the 
                                    //MPREQ flag to generate a MP3 interrupt.
    MP3CON |= MPEN;	                //enable the MP3 decoder.
}

void AudioInit()
{	
	AUDCON0 = 0x77;                                    //0111 0110
	AUDCON1 &= (~0xB0);                                //SRC=0,MSREQ=0,MUDRN=0
	AUDCON1 |= 0x01;
	AUDCON1 |= 0x40;
}

void MP3_Init(void)
{
	PllInit();
	MP3Init();
	AudioInit();
}

void PlayMP3()
{
		unsigned int i,j,total_size,readbyte;
		unsigned char data MP3_Framehead[4]; 

		i = 0;
		readbyte = ReadFile();      //Read 512 Bytes at first
/*		when the first 3 bytes are 49 44 33 the next can be 03,this means ID3 V2.3  */
		
		if (PageBuf[0] == 0x49)
			{
			 if ((PageBuf[1] == 0x44) && (PageBuf[2] == 0x33))
				{
					total_size = (PageBuf[6] & 0x7F) * 0x200000 + (PageBuf[7] & 0x7F) * 0x4000 + (PageBuf[8] & 0x7F) * 0x80 + (PageBuf[9] & 0x7F);
					while (total_size > 512)
					{
						ReadFile();
						total_size -=512;
					}

					i = total_size;

			        printu("Skip ID3V2\n");
					if (PageBuf[i] != 0xFF)	 //if not 0xFF,there is not the Frame head, but extend label 
				        {i += 10;
						 printu("Skip Extend Label\n");
						}
				}
			 }
		else printu("No ID3V2\n");

		printuf16x("Frame Header Offset in Page is %x\n",i);

    	if ((PageBuf[i] == 0xFF) && (PageBuf[i + 1] & 0xF0 == 0xF0))//get MP3 information from FF FX XX XX 4bytes,
			{
				MP3_Framehead[0] = PageBuf[i];
				MP3_Framehead[1] = PageBuf[i + 1];
				MP3_Framehead[2] = PageBuf[i + 2];
				MP3_Framehead[3] = PageBuf[i + 3];
				printu("MP3 Frame Header is ");
				for(j=0;j<4;j++)
					printuf("%x ",MP3_Framehead[j]);
				printu("\n");
			}

		if (MP3_Framehead[1] & 0x08) 
			{
				switch ((MP3_Framehead[2] & 0x0C) >> 2) 
				{
					case 0x00 : MP3FsInit(24, 126, 3, 5); 
					            printu("Bit Rate is 44.1 KHz\n");break;         //Fs=44.1kHz
					case 0x01 : MP3FsInit(124, 575, 3, 4); 
								printu("Bit Rate is 48 KHz\n");break;         //Fs=48kHz
					default : break;
				}
			} 
		else 
			{
				switch ((MP3_Framehead[2] & 0x0C) >> 2)
				{
					case 0x00 : MP3FsInit(24, 126, 3, 11); 
								printu("Bit Rate is 22.05 KHz\n");break;         //Fs=22.05kHz
					case 0x01 : MP3FsInit(124, 575, 3, 9); 
								printu("Bit Rate is 24 KHz\n");break;         //Fs=24kHz
					default : break;
				}
			}

		for (j=i; j<readbyte; j++) 	   	//将已经读到的Page写入MP3解码器
			{
			 while (!(MP3STA1 & MPBREQ)); 
			 MP3DAT = PageBuf[j]; 
			}		
		while (1)
		   {   
			readbyte = ReadFile(); 	   //继续读Page并送入MP3解码器
			for (i=0; i<readbyte; i++) 
				{
				 while (!(MP3STA1 & MPBREQ)); 
				 MP3DAT = PageBuf[i]; 
				}
			
			if (readbyte < 512) 
				return;
	    	}
}