SD卡WAV音乐播放器（quartus11.0）（FAT32）（DE2-115）

准备工具：格式工厂，Windows录音机，SD卡（小于等于2G），音箱

　　首先，选一首MP3，用格式工场转化成WAV格式。可以看到转化后的文件变得很大，因为WAV就是AD采样值加个文件头，所以数据量巨大，这也是MP3压缩算法流行的原因。

　　将转化后的WAV文件用Windows录音机打开编辑，采样率设置为8Khz,16位立体声，然后写入到SD卡里，恩，这里提一句，可以写入任意数量的歌曲，我写的程序是播放完卡里所有的WAV文件。当然别放其他文件例如图片文件进去捣乱啊，文件系统里没有识别其他文件的过程，开学了，要忙活了就没做。

　　硬件搭建：

　　SD卡的部分就不说了，前面博客提过了。说说WM8731吧，我们管这个芯片叫霸气闪耀，因为它里面有24位的ADC和DAC，而且是CD音质，听起来感觉不错的。驱动芯片首先当然是看手册，50多页的手册，还凑合。我们关心的只有几个部分：DAC，控制接口，数据接口。先来看看它的框图：

由于我们是将SD卡里的数字数据读出来，写入DAC，所以我们不管ADC的部分，注意这三个红圈，上面的红圈是控制接口，是用户控制8731工作模式写命令的接口，接口采用I2C协议；右边的红圈是耳机输出，默认是静音，坑爹啊，这个设置一样要改，不然没声的。下面的红圈是数据接口，我们的数据数据从这里串行输入。好，明确了这些概念后，我们来看8731的控制寄存器。如下图：

8731一共11个寄存器，保守起见，每个都设置一遍最好。这里还有个坑爹的地方，开始看手册不细，被耍的够惨。这个复位寄存器，当我们写入复位命令后，8731就将所有的控制寄存器先写入0.本来一上电，8731会自己复位，并且自动配置寄存器的值，但是这个软件复位的效果和上电复位的不一样，上电复位后控制寄存器里的值不是0，而是一些默认的设置，软件复位后，所有的都是零了。

　　扯一扯I2C协议

　　I2C协议点对点传输还是比较简单的，不用考虑仲裁等乱七八糟的事。8731的I2C协议如下图所示：

注意8731的设备号是可变的，而DE2-115上已经将其固定为0X34了，最后一位是读写选择，8731是只写的，不能读，所以地址加上R/W位就是0X34。发送完8位设备地址加读写位后，接下来发送16位数据，前7位是8731内部寄存器的地址，后9位是寄存器配置的数据。每一个命令封装成24位的一帧，每次发送命令都要完整的发送：起始标志，设备号，读写位，7位寄存器地址，9位数据。

　　命令接口说完了，接下来是数据接口，这个有些麻烦。我们要写入串行的数据，就要自己写并转串的接口。数据写入有四种模式：左对齐，I2S，和右对齐，DSP模式。继续看手册：

左对齐模式，也是我采用的模式，数据在DACLRCK的下降沿后BCLK的第一个上升沿就有效。

I2S模式，数据会延迟一个BCLK才有效。

右对齐模式，就是数据最高位和DACLRCK的下降沿对齐。

不在以DACLRCK的高低电平来区分左右声道了。数据时连续的。

我们采用左对齐方式，用硬件去实现高速的并转串接口。在检测到DACLRCK的下降沿或者上升沿后，使能模16计数器，当计数器计满时，使计数使能无效。在计数过程中，将并行数据移位输出到DACDAT引脚上。模块代码如下：

/*
*this file is use to connect the dule port ram and 8731
*when the up edge of lrck,read from the ram,and when the down edge of lrck,increace the ram address
*when the up edge of bclk,shift the 64 regs,and the msb is out to the 8731 dacda pin 
*/
module data_64
(
input clk,
input rst_n,
input [31:0]q,
input bclk,
input lrck,
output q_out,
output rd_en,
output [16:0]ram_addr
);

//**************************************************************************************************
//up and down edge of lrck detect module
reg latch0;
reg latch1;
always@(posedge clk or negedge rst_n)
begin
    if(!rst_n)
    begin
        latch0<=1'b0;
        latch1<=1'b0;
    end
    else 
    begin
        latch0<=lrck;
        latch1<=latch0;
    end
end
wire up_detect;
wire down_detect;
assign up_detect=latch0 && (~latch1);
assign rd_en=up_detect;
assign down_detect=latch1 && (~latch0);

//****************************************************************************************************************
//up and down edge of bclk detect module
reg latch2;
reg latch3;
always@(posedge clk or negedge rst_n)
begin
    if(!rst_n)
    begin
        latch2<=1'b0;
        latch3<=1'b0;
    end
    else
    begin
        latch2<=bclk;
        latch3<=latch2;
    end
end
wire up;
wire down;
assign up=latch2 && (~latch3);
assign down=latch3 && (~latch2);

//************************************************************************************************************
//latch up_detect module,delay the up_detect for one clk for the data read from ram
reg write;
always@(posedge clk or negedge rst_n)
begin
    if(!rst_n)
        write<=1'b0;
    else
        write<=up_detect;
end

//*************************************************************************************************************
//64 reg module 
reg[31:0]data;
wire[23:0]gnd;
wire shift;
assign gnd=24'b0;
assign shift=1'b0;
always@(posedge clk or negedge rst_n)
begin
    if(!rst_n)
        data<=32'b0;
    else if(write)    
        data<=q[31:0];    
    else if(up && en)
        data<={data[30:0],shift};
end 
assign q_out=data[31];

//************************************************************************************************************
//ram addr generater
reg[16:0]addr;
always@(posedge clk or negedge rst_n)
begin
    if(!rst_n)
        addr<=17'b0;
    else if((addr==17'b11111_1111_1111_1111) && (down_detect ||up_detect))
        addr<=15'b0;
    else if(down_detect ||up_detect)
        addr<=addr+1'b1;
end
assign ram_addr=addr; 

//************************************************************************************************************
//counter enable module
reg en;
always@(posedge clk or negedge rst_n)
begin
    if(!rst_n)
        en<=1'b0;
    else if(cnt_over)
        en<=1'b0;
    else if(up_detect || down_detect)
        en<=1'b1;
end
//*************************************************************************************************************
//16 bits counter,count the BCLK posedge
reg[7:0]cnt;
wire cnt_over;
wire not_over;
always@(posedge clk or negedge rst_n)
begin
    if(!rst_n)
    begin
        cnt<=8'b0;
//        cnt_over<=1'b0;
    end
    else if((cnt==8'd16) && en )
    begin
        cnt<=8'b0;
//        cnt_over<=1'b1;
    end 
    else if(en && up)
    begin
        cnt<=cnt+1'b1;
//        cnt_over<=1'b0;
    end
end
assign cnt_over=(cnt==8'd16)?1'b1:1'b0;
assign not_over=~cnt_over;

endmodule 

　　本来这个模块式用来从ram里读数据的，后来发现ram只能缓存很小的数据，就改用FIFO了，但是地址线没有去掉。

　　建立一个FIFO来缓冲数据，数据位宽为32位，1024*32bit大小，其实用256*32bit也可以的。利用FIFO里面的WRUSEW的最高位（就是FIFO一半满时的标记），来决定是否写入数据。如图：

写请求是软件发出的，宽度不确定，那么我们写一个模块来检测它的上升沿，在上升沿出现时，产生一个clk宽度的信号，来向fifo写入数据。clk为100M。

module wr_req_detect
(
input clk,
input rst_n,
input wr_req,
output wr_req_detect
);
reg latch0;
reg latch1;
reg latch2;
always@(posedge clk or negedge rst_n)
begin
    if(!rst_n)
    begin
        latch0<=1'b0;
        latch1<=1'b0;
        latch2<=1'b0;
    end
    else 
    begin
        latch0<=wr_req;
        latch1<=latch0;
        latch2<=latch1;
    end
end
assign wr_req_detect=latch0 && (~latch1);
endmodule 

　　如果是assign wr_req_detect=latch0 && (~latch2);那么就是产生了2个clk宽度的写请求信号，具体原理不讲了，自己体会吧。

　　NIOS系统的搭建就是在SD卡系统的基础上多了几个PIO，分别是I2C的两条线，还有FIFO的数据线和写请求线。注意一个问题，FIFO的读写时钟全部同步到系统时钟，即用全局时钟来控制全局，利用使能时钟解决跨时钟域问题，用一个100M的时钟去检测几M的时钟的上升下降沿自然是没有问题的。

　　硬件就这么多可说的。

　　软件部分，FAT32文件系统，读取WAV跟读取BMP没有什么区别，只是后缀名不同而已，注意文件名不要搞太长，控制在8个字节内。直接贴代码了，我C语言是自学的，写的很菜，因为当时学汇编学的太狠了，导致写出来的C程序跟汇编一个味道，冗长，但是易懂，一看就明白。

　　头文件：

/*
 * sopc.h
 *
 *  Created on: 2011-8-10
 *      Author: Fu-xiaoliang
 */

#ifndef SOPC_H_
#define SOPC_H_
#include "system.h"
#define _LED
typedef struct
{
    unsigned long int DATA;
    unsigned long int DIRECTION;
    unsigned long int INTERRUPT_MASK;
    unsigned long int EDGE_CAPTURE;
}PIO_STR;
#ifdef _LED
#define SD_DA ((PIO_STR *)SD_DA_BASE)
#define SD_CMD ((PIO_STR *)SD_CMD_BASE)
#define SD_CS ((PIO_STR *)SD_CS_N_BASE)
#define SD_CLK ((PIO_STR *)SD_CLK_BASE)
#define WR_ADDR ((PIO_STR *)WR_ADDR_BASE)
#define WR_CLK ((PIO_STR *)WR_CLK_BASE)
#define WR_DAT ((PIO_STR *)WR_DAT_BASE)
#define WR_EN ((PIO_STR *)WR_EN_BASE)
#define WR_USE_W ((PIO_STR *)WR_USE_W_BASE)
#define RD_EN ((PIO_STR *)RD_EN_BASE)
#define I2C_DAT ((PIO_STR *)I2C_DAT_BASE)
#define I2C_SCLK ((PIO_STR *)I2C_SCLK_BASE)
#define LED ((PIO_STR *)LED_BASE)
#define _SD
#endif

#ifdef _SD
#define data (SD_DA->DATA)
#define cmd (SD_CMD->DATA)
#define cs (SD_CS->DATA)
#define clk (SD_CLK->DATA)
#endif
#define uc unsigned char
#endif /* SOPC_H_ */

　　主函数：

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/*  * "Hello World" example.  *  * This example prints 'Hello from Nios II' to the STDOUT stream. It runs on  * the Nios II 'standard', 'full_featured', 'fast', and 'low_cost' example  * designs. It runs with or without the MicroC/OS-II RTOS and requires a STDOUT  * device in your system's hardware.  * The memory footprint of this hosted application is ~69 kbytes by default  * using the standard reference design.  *  * For a reduced footprint version of this template, and an explanation of how  * to reduce the memory footprint for a given application, see the  * "small_hello_world" template.  *  */   #include <stdio.h> #include "alt_types.h"  // alt_u32 #include <unistd.h> #include "sys/alt_irq.h" #include "D:\FPGA-PROJECT\myself\SD_WAV_DE2\software\DE2_SD_WAV\inc\sopc.h"   //**************************************************************************************************************************** //static variable uc Resp_buffer[16]={0}; uc data_buffer[512]={0}; uc data_buffer1[512]={0}; unsigned long int FDT_DIRECT[16]={0}; uc not_finish=0;     unsigned long int DBR_ADDR=0;   unsigned long int FAT1_ADDR=0;   unsigned long int FAT2_ADDR=0;   unsigned long int FDT_ADDR=0;   unsigned long int CLUS_ADDR=0;   unsigned long int CLUS_CURRENT=0;//current clus number   unsigned long int CLUS_LEN=0;//clus lenth   unsigned long int CLUS_NEXT=0;   unsigned long int RAM_ADDR=0;    struct {     union     {         unsigned char CSD[16];         unsigned char CSD1[16];     }CSD_DA;     union     {         unsigned char buf1[16];         unsigned char buf2[16];       }CID_DA; }REG;   struct {   uc  RIFF_ID[4];   unsigned long long int  WAV_SIZE;   uc  RIFF_TYPE[4]; }WAV_RIFF_CHUNK;   struct {    uc FORMAT_ID[4];    unsigned long long int  FORMAT_SIZE;    unsigned long int FORMAT_TAG;    unsigned long int CHANNELS;    unsigned long long int SAMPLES_PER_SEC;    unsigned long long int BYTE_PER_SEC;    unsigned long int BLOCK_ALIGN;    unsigned long int BITS_PER_SAMPLE;    unsigned long int ADDITION; }WAV_FORMAT_CHUNK;   struct {   uc FACT_ID[4];   unsigned long long int FACT_SIZE;   unsigned long long int FACT_DATA; }WAV_FACT_CHUNK;   struct {   uc DATA_ID[4];   unsigned long long int DATA_SIZE;   }WAV_DATA_CHUNK;   //********************************************************************************************************************************************* //function define and statement uc send_byte(uc sda) {     uc cnt=0,rda=0;     SD_CLK->DATA=1;     SD_CMD->DIRECTION=1;     for(cnt=0;cnt<8;cnt++)     {         SD_CLK->DATA=0;         SD_CMD->DATA=0;         if(sda & 0x80)             SD_CMD->DATA=1;         usleep(50);         sda=sda<<1;         rda=rda<<1;         SD_CLK->DATA=1;         if(SD_DA->DATA)         {               rda=rda|0x01;         }       }       SD_CLK->DATA=1;     return rda; } uc send_byte_fast(uc sda) {     uc cnt=0,rda=0;     SD_CLK->DATA=1;     SD_CMD->DIRECTION=1;     for(cnt=0;cnt<8;cnt++)     {         SD_CLK->DATA=0;         SD_CMD->DATA=0;         if(sda & 0x80)             SD_CMD->DATA=1; //      usleep(70);         sda=sda<<1;         rda=rda<<1;         SD_CLK->DATA=1;         if(SD_DA->DATA)         {               rda=rda|0x01;         }     }     SD_CLK->DATA=1;     return rda; } uc i2c_send_3byte(uc x,uc y,uc z) {     uc i=0;uc a=0;     I2C_SCLK->DATA=0;     I2C_DAT->DIRECTION=1;     I2C_DAT->DATA=1;     I2C_SCLK->DATA=1;//initial I2C clk and data line     usleep(10);     I2C_DAT->DATA=0;//start transfer     usleep(10);     I2C_SCLK->DATA=0;     usleep(10);     for(i=0;i<8;i++)//send first byte     {         usleep(10);         I2C_DAT->DATA=(x & 0x80)?1:0;         I2C_SCLK->DATA=1;         x=x<<1;         usleep(10);         I2C_SCLK->DATA=0;     }     I2C_DAT->DIRECTION=0;     I2C_SCLK->DATA=1;     usleep(10);     a=I2C_DAT->DATA;     if(a==0)     {         printf("slave replay first byte!\n");     }     else         printf("slave no replay !\n");       I2C_DAT->DIRECTION=1;     I2C_SCLK->DATA=0;     usleep(10);     for(i=0;i<8;i++)//send second byte     {         I2C_DAT->DATA=(y & 0x80)?1:0;         usleep(10);         I2C_SCLK->DATA=1;         y=y<<1;         usleep(10);         I2C_SCLK->DATA=0;     }     I2C_DAT->DIRECTION=0;     I2C_SCLK->DATA=1;     usleep(10);     a=I2C_DAT->DATA;     if(a==0)     {         printf("slave replay second byte!\n");     }     else         printf("slave no replay !\n");       I2C_DAT->DIRECTION=1;     I2C_SCLK->DATA=0;     usleep(10);     for(i=0;i<8;i++)//send third byte     {         I2C_DAT->DATA=(z & 0x80)?1:0;         usleep(10);         I2C_SCLK->DATA=1;         z=z<<1;         usleep(10);         I2C_SCLK->DATA=0;     }     I2C_DAT->DIRECTION=0;     I2C_SCLK->DATA=1;     usleep(10);     a=I2C_DAT->DATA;     if(a==0)     {         printf("slave replay third byte!\n");     }     else         printf("slave no replay !\n");       I2C_DAT->DIRECTION=1;     I2C_SCLK->DATA=0;     I2C_DAT->DATA=0;     I2C_SCLK->DATA=1;     usleep(10);     I2C_DAT->DATA=1;//form the stop bit       return 0; }   uc wav_init() {     uc i=0;     for(i=0;i<4;i++)     {       WAV_RIFF_CHUNK.RIFF_ID[i]=data_buffer1[i];        WAV_RIFF_CHUNK.RIFF_TYPE[i]=data_buffer1[i+8];     }     WAV_RIFF_CHUNK. WAV_SIZE=data_buffer1[4]|(data_buffer1[5]<<8)|(data_buffer1[6]<<16)|(data_buffer1[24]);       for(i=0;i<4;i++)     {        WAV_FORMAT_CHUNK.FORMAT_ID[i]=data_buffer1[i+12];     }     WAV_FORMAT_CHUNK.FORMAT_SIZE=data_buffer1[16]|(data_buffer1[17]<<8)|(data_buffer1[18]<<16)|(data_buffer1[19]<<24);     WAV_FORMAT_CHUNK.FORMAT_TAG=data_buffer1[20]|(data_buffer1[21]<<8);     WAV_FORMAT_CHUNK.CHANNELS=data_buffer1[22]|(data_buffer1[23]<<8);     WAV_FORMAT_CHUNK.SAMPLES_PER_SEC=data_buffer1[24]|(data_buffer1[25]<<8)|(data_buffer1[26]<<16)|(data_buffer1[27]<<24);     WAV_FORMAT_CHUNK.BYTE_PER_SEC=data_buffer1[28]|(data_buffer1[29]<<8)|(data_buffer1[30]<<16)|(data_buffer1[31]<<24);     WAV_FORMAT_CHUNK.BLOCK_ALIGN=data_buffer1[32]|(data_buffer1[33]<<8);     WAV_FORMAT_CHUNK.BITS_PER_SAMPLE=data_buffer1[34]|(data_buffer1[35]<<8);     WAV_FORMAT_CHUNK.ADDITION=data_buffer1[36]|(data_buffer1[37]<<8);       for(i=0;i<4;i++)     {       WAV_FACT_CHUNK.FACT_ID[i]=data_buffer1[i+38];     }      WAV_FACT_CHUNK.FACT_SIZE=data_buffer1[42]|(data_buffer1[43]<<8)|(data_buffer1[44]<<16)|(data_buffer1[45]<<24);      WAV_FACT_CHUNK.FACT_DATA=data_buffer1[46]|(data_buffer1[47]<<8)|(data_buffer1[48]<<16)|(data_buffer1[49]<<24);        for(i=0;i<4;i++)      {         WAV_DATA_CHUNK.DATA_ID[i]=data_buffer1[i+50];      }      WAV_DATA_CHUNK.DATA_SIZE=data_buffer1[54]|(data_buffer1[55]<<8)|(data_buffer1[56]<<16)|(data_buffer1[57]<<24);        return 0; }   uc wm8731_init() {     i2c_send_3byte(0x34,0x1e,0x00);//reset 8731     i2c_send_3byte(0x34,0x12,0x00);//inactive     i2c_send_3byte(0x34,0x00,0x17);//left volume     i2c_send_3byte(0x34,0x02,0x17);//right volume     i2c_send_3byte(0x34,0x04,0x7b);//left headphone     i2c_send_3byte(0x34,0x06,0x7b);//right headphone     i2c_send_3byte(0x34,0x08,0x3d);//select DAC channel     i2c_send_3byte(0x34,0x0a,0x00);//do not quiet     i2c_send_3byte(0x34,0x0c,0x00);//power on the device     i2c_send_3byte(0x34,0x0e,0x41);//master ,16bit and left mode     i2c_send_3byte(0x34,0x10,0x0c);//sampling clock control set normal mode,8KHZ     i2c_send_3byte(0x34,0x12,0x01);//active     i2c_send_3byte(0x34,0x12,0x00);//inactive     return 0; }   uc write_CMD0(void) {         uc a=0,i=0;         SD_CS->DATA=1;         send_byte(0xff);         SD_CS->DATA=0;         send_byte(0x40);         send_byte(0x00);         send_byte(0x00);         send_byte(0x00);         send_byte(0x00);         send_byte(0x95);         do         {             a=send_byte(0xff);             i++;             if(i==200)             {                 printf("CMD0 no replay\n");                 break;             }         }while(a!=0x01);         return a; } uc send_CMD(uc number,uc x,uc y,uc z,uc w, uc u,uc v,uc r) {     uc b=0,i=0;     SD_CS->DATA=1;     send_byte_fast(0xff);     SD_CS->DATA=0;     send_byte_fast(x);     send_byte_fast(y);     send_byte_fast(z);     send_byte_fast(w);     send_byte_fast(u);     send_byte_fast(v);     do     {         b=send_byte_fast(0xff);         i++;         if(i==200)         {             printf("CMD%d no replay\n",number);             break;         }     }while(b!=r);     return b; } uc write_CMD1(void) {     uc a=0,i=0;     SD_CS->DATA=1;     send_byte(0xff);     SD_CS->DATA=0;     send_byte(0x41);     send_byte(0x00);     send_byte(0x00);     send_byte(0x00);     send_byte(0x00);     send_byte(0xff);     do     {         a=send_byte(0xff);         i++;         if(i==200)         {             printf("CMD1 no replay\n");             break;         }     }while(a!=0x00);     return a; }   uc sd_init(void) {     uc i=0;     uc a,b;     SD_CS->DATA=1;     for(i=0;i<100;i++)     {         send_byte(0xff);     }     usleep(250);     i=0;     do     {         b=write_CMD0();         i++;         if(i==100)             break;     }while(b!=0x01);     printf("CMD0 replay %x\n",b);     i=0;     do         {             a=write_CMD1();             i++;             if(i==100)                 break;         }while(a!=0x00);         printf("CMD1 replay %x\n",a);         i=0;         do         {             a=send_CMD(16,0x50,0x00,0x00,0x02,0x00,0xff,0x00);             i++;             if(i==10)                 break;         }while(a!=0x00);     printf("CMD16 replay %x\n",a);     i=0;     do     {         a=send_CMD(59,0x7b,0x00,0x00,0x00,0x00,0xff,0x00);         i++;         if(i==10)             break;     }while(a!=0x00);     printf("CMD59 replay %x\n",a);     i=0;     do     {         a=send_CMD(9,0x49,0x00,0x00,0x00,0x00,0xff,0x00);         i++;         if(i==10)             break;     }while(a!=0x00);     printf("CMD9 replay %x\n",a);     if(a==0x00)     {         uc tem=0;         do         {             printf("tem is %x\n",tem);             tem=send_byte(0xff);         }while(tem!=0xfe);         printf("tem is %x\n",tem);         if(tem==0xfe)         {             printf("0xfe is received\n");             for(i=0;i<16;i++)             {                 Resp_buffer[i]=send_byte(0xff);             }             send_byte(0xff);             send_byte(0xff);             SD_CS->DATA=1;             send_byte(0xff);         }     }     for(i=0;i<16;i++)     {         printf("CSD is %x\n",Resp_buffer[i]);         REG.CSD_DA.CSD[i]=Resp_buffer[i];     }     return 0; }   void ISR_neg(void *context,unsigned long id) { /*  i=0;         do{             a=send_CMD(17,0x51,(((CLUS_ADDR+512*k)&0xff000000)>>24),(((CLUS_ADDR+512*k)&0x00ff0000)>>16),(((CLUS_ADDR+512*k)&0x0000ff00)>>8),((CLUS_ADDR+512*k)&0xff),0xff,0x00);             i++;             if(i==100)                 break;             }while(a!=0x00);         if(a==0x00)         {             uc temp=0;             int j=0;;             do{                 temp=send_byte_fast(0xff);                 j++;                 }while(temp!=0xfe && j<100);*/     int j;     for(j=0;j<509;j=j+4)     {           data_buffer1[j]=send_byte_fast(0xff);         data_buffer1[j+1]=send_byte_fast(0xff);         data_buffer1[j+2]=send_byte_fast(0xff);         data_buffer1[j+3]=send_byte_fast(0xff);         if((data_buffer1[0]==0x52) && (data_buffer1[1]=0x49) && (data_buffer1[2]==0x46) && (data_buffer1[3]==0x46))         {             if(j>=58)             {             WR_EN->DATA=0;             WR_DAT->DATA=data_buffer1[j]|(data_buffer1[j+1]<<8)|(data_buffer1[j+2]<<16)|(data_buffer1[j+3]<<24);             WR_EN->DATA=1;             }         }         else         {             WR_EN->DATA=0;             WR_DAT->DATA=data_buffer1[j]|(data_buffer1[j+1]<<8)|(data_buffer1[j+2]<<16)|(data_buffer1[j+3]<<24);             WR_EN->DATA=1;         }     } }   int init_neg(void) {     WR_USE_W->INTERRUPT_MASK=1;     return alt_irq_register(WR_USE_W_IRQ,NULL,ISR_neg); }   //********************************************************************************************************************************************* //the main function int main() {   int i=0,j=0,k=0,cnt=0;   unsigned int index=0;   uc a;   for(i=0;i<8;i++)   {       LED->DATA=1<<i;       usleep(500000);   }     SD_CS->DATA=1;     SD_CMD->DIRECTION=1;     SD_CMD->DATA=1;       sd_init();     wm8731_init();     i=0;     do     {         a=send_CMD(10,0x4a,0x00,0x00,0x00,0x00,0xff,0x00);         i++;         if(i==10)             break;     }while(a!=0x00);     printf("CMD10 replay %x\n",a);     if(a==0x00)     {         uc tem=0;         do         {             printf("tem is %x\n",tem);             tem=send_byte(0xff);         }while(tem!=0xfe);         printf("tem is %x\n",tem);         if(tem==0xfe)         {             printf("0xfe is received\n");             for(i=0;i<16;i++)             {                   Resp_buffer[i]=send_byte(0xff);             }             send_byte(0xff);             send_byte(0xff);             SD_CS->DATA=1;             send_byte(0xff);         }         for(i=0;i<16;i++)         {             printf("CID is %x\n",Resp_buffer[i]);             REG.CID_DA.buf1[i]=Resp_buffer[i];         }     }       i=0;     do     {         a=send_CMD(17,0x51,0x00,0x00,0x00,0x00,0xff,0x00);         i++;         if(i==100)             break;     }while(a!=0x00);     printf("CMD17 replay %x\n",a);     if(a==0x00)     {         uc temp=0;         int j=0;;         do{             printf("temp is %x\n",temp);             temp=send_byte_fast(0xff);             j++;         }while(temp!=0xfe && j<100);     printf("temp is %x\n",temp);     if(temp==0xfe)     {         printf("0xfe is received\n");         printf("block 0 data is followed\n");         for(j=0;j<512;j++)         {               data_buffer[j]=send_byte_fast(0xff);         }         i=0;         for(j=0;j<512;j++)         {             printf("%x ",data_buffer[j]);             i++;             if(i==16)             {                 i=0;                 printf("\n");             }         }     }     }     if((data_buffer[0]==0x00)||(data_buffer[0]!=0xeb)||(data_buffer[0]!=0xe9))//judge the weather first block is DBR or not     {           DBR_ADDR=(((DBR_ADDR|data_buffer[457])<<24)|((DBR_ADDR|data_buffer[456])<<16)|((DBR_ADDR|data_buffer[455])<<8)|data_buffer[454])*512;         i=0;         do{             a=send_CMD(17,0x51,((DBR_ADDR&0xff000000)>>24),((DBR_ADDR&0x00ff0000)>>16),((DBR_ADDR&0x0000ff00)>>8),(DBR_ADDR&0xff),0xff,0x00);             i++;             if(i==100)                 break;             }while(a!=0x00);         if(a==0x00)         {             uc temp=0;             int j=0;;             do{                 printf("temp is %x\n",temp);                 temp=send_byte_fast(0xff);                 j++;                 }while(temp!=0xfe && j<100);                 printf("temp is %x\n",temp);                 if(temp==0xfe)                 {                     printf("0xfe is received\n");                     printf("DBR data is followed\n");                     for(j=0;j<512;j++)                     {                           data_buffer[j]=send_byte_fast(0xff);                     }                     i=0;                     for(j=0;j<512;j++)                     {                         printf("%x ",data_buffer[j]);                         i++;                         if(i==16)                         {                             i=0;                             printf("\n");                         }                     }                   }             }         }         else         {             DBR_ADDR=0;         }         FAT1_ADDR=DBR_ADDR+((data_buffer[14]|(data_buffer[15]<<8))*512);         FAT2_ADDR=FAT1_ADDR+((data_buffer[36]|(data_buffer[37]<<8))*512);         FDT_ADDR=FAT2_ADDR+((data_buffer[36]|(data_buffer[37]<<8))*512);         CLUS_LEN=data_buffer[13]*512;         printf("FAT1_ADDR is %lx \n",FAT1_ADDR);         printf("FAT2_ADDR is %lx \n",FAT2_ADDR);         printf("FDT_ADDR is %lx \n",FDT_ADDR);         printf("DBR_ADDR is %lx \n",DBR_ADDR);         printf("CLUS_LEN is %lx \n",CLUS_LEN);         i=0;         do{             //read the FDT             a=send_CMD(17,0x51,((FDT_ADDR&0xff000000)>>24),((FDT_ADDR&0x00ff0000)>>16),((FDT_ADDR&0x0000ff00)>>8),(FDT_ADDR&0xff),0xff,0x00);             i++;             if(i==100)                 break;             }while(a!=0x00);         if(a==0x00)         {             uc temp=0;             int j=0;             do{                 printf("temp is %x\n",temp);                 temp=send_byte_fast(0xff);                 j++;                 }while(temp!=0xfe && j<100);                 printf("temp is %x\n",temp);                 if(temp==0xfe)                 {                     printf("0xfe is received\n");                     printf("FDT data is followed\n");                     for(j=0;j<512;j++)                     {                         data_buffer[j]=send_byte_fast(0xff);                     }                 i=0;                 for(j=0;j<512;j++)                 {                     printf("%x ",data_buffer[j]);                     i++;                     if(i==16)                     {                         i=0;                         printf("\n");                     }                 }             }         }     for(i=0,j=0;i<512;i=i+32)     {         if((data_buffer[11+i]==0x08)&&(data_buffer[i]!=0xe5))//find the juan biao         {             printf("juan biao is %d\n",i+11);             continue;         }         else if((data_buffer[11+i]==0x20)&&(data_buffer[i]!=0xe5))//find the file         {             CLUS_CURRENT=(data_buffer[20+i]<<16)|(data_buffer[21+i]<<24)|(data_buffer[27+i]<<8)|(data_buffer[26+i]);//first clus addr             printf("first clus is %ld\n",CLUS_CURRENT);             FDT_DIRECT[j]=CLUS_CURRENT;//store the current clus addr             j++;             continue;         }         else if(data_buffer[i]==0xe5)             continue;         else if(data_buffer[i]==0x00)         {             break;             not_finish=0;//no file behind         }     }     i=0;     do{         //read FAT1         a=send_CMD(17,0x51,((FAT1_ADDR&0xff000000)>>24),((FAT1_ADDR&0x00ff0000)>>16),((FAT1_ADDR&0x0000ff00)>>8),(FAT1_ADDR&0xff),0xff,0x00);         i++;         if(i==100)             break;         }while(a!=0x00);     if(a==0x00)     {         uc temp=0;         int j=0;;         do{             printf("temp is %x\n",temp);             temp=send_byte_fast(0xff);             j++;             }while(temp!=0xfe && j<100);             printf("temp is %x\n",temp);             if(temp==0xfe)             {                 printf("0xfe is received\n");                 printf("FAT1 data is followed\n");                 for(j=0;j<512;j++)                 {                     data_buffer[j]=send_byte_fast(0xff);                 }             i=0;             for(j=0;j<512;j++)             {                 printf("%x ",data_buffer[j]);                 i++;                 if(i==16)                 {                     i=0;                     printf("\n");                 }             }           }     }     CLUS_ADDR=(FDT_DIRECT[0]-2)*CLUS_LEN+FDT_ADDR;//first data clus address     CLUS_NEXT=data_buffer[(FDT_DIRECT[0]*4)]|(data_buffer[(FDT_DIRECT[0]*4+1)]<<8)|(data_buffer[(FDT_DIRECT[0]*4+2)]<<16)|(data_buffer[(FDT_DIRECT[0]*4+3)]<<24); //  CLUS_ADDR=(CLUS_CURRENT-2)*CLUS_LEN+FDT_ADDR;//first data clus address //  CLUS_NEXT=data_buffer[CLUS_CURRENT*4]|(data_buffer[CLUS_CURRENT*4+1]<<8)|(data_buffer[CLUS_CURRENT*4+2]<<16)|(data_buffer[CLUS_CURRENT*4+3]<<24); //  printf("CLUS_NEXT is %lx\n",CLUS_NEXT);     index=0;     cnt=0;     do{     do{         CLUS_ADDR=(FDT_DIRECT[cnt]-2)*CLUS_LEN+FDT_ADDR;//first data clus address         FDT_DIRECT[cnt]=CLUS_NEXT;         CLUS_NEXT=FDT_DIRECT[cnt]+1;//data_buffer[(FDT_DIRECT[cnt]*4-512*index)]|(data_buffer[(FDT_DIRECT[cnt]*4+1-512*index)]<<8)|(data_buffer[(FDT_DIRECT[cnt]*4+2-512*index)]<<16)|(data_buffer[(FDT_DIRECT[cnt]*4+3-512*index)]<<24); //      FDT_DIRECT[cnt]=CLUS_NEXT; /*      if((FDT_DIRECT[cnt]*4+3)>=511)         {             FDT_DIRECT[cnt]=0;             index++;             i=0;             do{                 //read FAT1 next 512 byte                 a=send_CMD(17,0x51,(((FAT1_ADDR+512*index)&0xff000000)>>24),(((FAT1_ADDR+512*index)&0x00ff0000)>>16),(((FAT1_ADDR+512*index)&0x0000ff00)>>8),((FAT1_ADDR+512*index)&0xff),0xff,0x00);                 i++;                 if(i==100)                     break;                 }while(a!=0x00);             printf("a is %x\n",a);             if(a==0x00)             {                 uc temp=0;                 int j=0;;                 do{                     printf("temp is %x\n",temp);                     temp=send_byte_fast(0xff);                     j++;                     }while(temp!=0xfe && j<100);                     printf("temp is %x\n",temp);                     if(temp==0xfe)                     {                         printf("0xfe is received\n");                         printf("FAT1 next 512b data is followed\n");                         for(j=0;j<512;j++)                         {                             data_buffer[j]=send_byte_fast(0xff);                         }                         i=0;                         for(j=0;j<512;j++)                         {                             printf("%x ",data_buffer[j]);                             i++;                             if(i==16)                             {                                 i=0;                                 printf("\n");                             }                         }                   }             }         }*/ //      CLUS_ADDR=(CLUS_CURRENT-2)*CLUS_LEN+FDT_ADDR; //      CLUS_CURRENT=CLUS_NEXT; //      CLUS_NEXT=data_buffer[CLUS_CURRENT*4]|(data_buffer[CLUS_CURRENT*4+1]<<8)|(data_buffer[CLUS_CURRENT*4+2]<<16)|(data_buffer[CLUS_CURRENT*4+3]<<24); //      for(k=0;k<8;k++)//for each clus has 8 512Byte //      {             k=0;             while(!WR_USE_W->DATA)             {             i=0;             do{             a=send_CMD(17,0x51,(((CLUS_ADDR+512*k)&0xff000000)>>24),(((CLUS_ADDR+512*k)&0x00ff0000)>>16),(((CLUS_ADDR+512*k)&0x0000ff00)>>8),((CLUS_ADDR+512*k)&0xff),0xff,0x00);             i++;             if(i==100)                 break;             }while(a!=0x00); //          printf("read data a is %x\n",a);             if(a==0x00)             {                 uc temp=0;                 int j=0;                 do{ //                  printf("temp is %x\n",temp);                     temp=send_byte_fast(0xff);                     j++;                     }while(temp!=0xfe && j<100); //                  printf("temp is %x\n",temp);                     if(temp==0xfe)                     { //                      printf("0xfe is received\n"); //                      printf("first clus data is followed\n");                         for(j=0;j<509;j=j+4)                         {                               data_buffer1[j]=send_byte_fast(0xff);                             data_buffer1[j+1]=send_byte_fast(0xff);                             data_buffer1[j+2]=send_byte_fast(0xff);                             data_buffer1[j+3]=send_byte_fast(0xff);                             if((data_buffer1[0]==0x52) && (data_buffer1[1]=0x49) && (data_buffer1[2]==0x46) && (data_buffer1[3]==0x46))                             {                                 if(j>=58)                                 {                                     WR_EN->DATA=0;                                     WR_DAT->DATA=data_buffer1[j]|(data_buffer1[j+1]<<8)|(data_buffer1[j+2]<<16)|(data_buffer1[j+3]<<24);                                     WR_EN->DATA=1;                                 }                             }                             else                             {                                 WR_EN->DATA=0;                                 WR_DAT->DATA=data_buffer1[j]|(data_buffer1[j+1]<<8)|(data_buffer1[j+2]<<16)|(data_buffer1[j+3]<<24);                                 WR_EN->DATA=1;                             }                         } /*                  i=0;                     for(j=0;j<512;j++)                     {                         usleep(10);                         printf("%x ",data_buffer1[j]);                         i++;                         if(i==16)                         {                             i=0;                             printf("\n");                         }                     }*/                   }             }             k++; //          if(k==8) //              break;             }             i2c_send_3byte(0x34,0x12,0x01);//active //          printf("enable display!\n"); //          while(WR_USE_W->DATA);             while(1)             {                 while(!WR_USE_W->DATA)                 {                     i=0;                     do{                     a=send_CMD(17,0x51,(((CLUS_ADDR+512*k)&0xff000000)>>24),(((CLUS_ADDR+512*k)&0x00ff0000)>>16),(((CLUS_ADDR+512*k)&0x0000ff00)>>8),((CLUS_ADDR+512*k)&0xff),0xff,0x00);                     i++;                     if(i==100)                         break;                     }while(a!=0x00);                     if(a==0x00)                     {                         uc temp=0;                         int j=0;                         do{         //                  printf("temp is %x\n",temp);                             temp=send_byte_fast(0xff);                             j++;                             }while(temp!=0xfe && j<100);         //                  printf("temp is %x\n",temp);                             if(temp==0xfe)                             {         //                      printf("0xfe is received\n");         //                      printf("first clus data is followed\n");                                 for(j=0;j<509;j=j+4)                                 {                                       data_buffer1[j]=send_byte_fast(0xff);                                     data_buffer1[j+1]=send_byte_fast(0xff);                                     data_buffer1[j+2]=send_byte_fast(0xff);                                     data_buffer1[j+3]=send_byte_fast(0xff); /*                                  if((data_buffer1[0]==0x52) && (data_buffer1[1]=0x49) && (data_buffer1[2]==0x46) && (data_buffer1[3]==0x46))                                     {                                         if(j>=58)                                         {                                             WR_EN->DATA=0;                                             WR_DAT->DATA=data_buffer1[j]|(data_buffer1[j+1]<<8)|(data_buffer1[j+2]<<16)|(data_buffer1[j+3]<<24);                                             WR_EN->DATA=1;                                         }                                     }*/ //                                  else //                                  {                                         WR_EN->DATA=0;                                         WR_DAT->DATA=data_buffer1[j]|(data_buffer1[j+1]<<8)|(data_buffer1[j+2]<<16)|(data_buffer1[j+3]<<24);                                         WR_EN->DATA=1; //                                  }                                 }                             }                     }                     k++;                     if(k==8)                         break;                 }                 if(k==8)                     break;             } //  } //the for loop     }while(CLUS_NEXT!=0x0fffffff);     cnt++;     CLUS_NEXT=data_buffer[(FDT_DIRECT[cnt]*4)]|(data_buffer[(FDT_DIRECT[cnt]*4+1)]<<8)|(data_buffer[(FDT_DIRECT[cnt]*4+2)]<<16)|(data_buffer[(FDT_DIRECT[cnt]*4+3)]<<24);     }while(FDT_DIRECT[cnt]!=0);         SD_CS->DATA=1;         unsigned long int cap;         double  c;         //(c_size+1)*mult*(1<<read_bl_len)         cap=((((REG.CSD_DA.CSD[6]&0x03)<<10) | (REG.CSD_DA.CSD[7]<<2) | ((REG.CSD_DA.CSD[8]&0xC0)>>6) + 1))*(1 << ((((REG.CSD_DA.CSD[9]&0x03)<<1) | ((REG.CSD_DA.CSD[10]&0x80)>>7)) + 2))*(1<<(REG.CSD_DA.CSD[5]&0x0f));         printf("capacity is %ld MB\n",cap/1048576);         printf("read_bl_len is %d B\n",(1<<(REG.CSD_DA.CSD[5]&0x0f)));         c=((double)cap/1073741824);         printf("capacity is %f GB\n",c);     printf("send CMD0!\n");   return 0;   }

　　　有很多没用到的引脚，我没删除，留着扩展用吧，另外我没用中断，虽然生命了函数，但是是用电平检测来做的，担心中断容易出BUG。

　　采样频率没法再提高了，SD卡读取还是比较慢的，我尝试了32K和48K ，都失败了，放出来的声音简直是闹鬼，不过我同学说，8K的效果也很不错了，一点噪音没有。

　　播放结束后，手动按复位键重新开始播放，不然会将卡里的数据都用DAC播放出来，呵呵，我没检测文件簇结束标志0X0FFFFFFF，所以它会一直不停的播放下去，我也懒得改了。　

我觉得应该有办法将采样频率提高到48K的，因为友晶的范例是用的44.1K的采样频率，我这篇是原创，完全没有按他们的思路来。从电路到程序全是自己搞的。

转载自：http://www.cnblogs.com/lamapig/archive/2011/09/01/2162047.html