关于SD卡的读取问题 DE2
这是SD_card.h文件的内容：
#ifndef __SD_Card_H__
#define __SD_Card_H__
//-------------------------------------
// SD Card Set I/O Direction
#define SD_CMD_IN IOWR(SD_CMD_BASE, 1, 0)
#define SD_CMD_OUT IOWR(SD_CMD_BASE, 1, 1)
#define SD_DAT_IN IOWR(SD_DAT_BASE, 1, 0)
#define SD_DAT_OUT IOWR(SD_DAT_BASE, 1, 1)
// SD Card Output High/Low
#define SD_CMD_LOW IOWR(SD_CMD_BASE, 0, 0)
#define SD_CMD_HIGH IOWR(SD_CMD_BASE, 0, 1)
#define SD_DAT_LOW IOWR(SD_DAT_BASE, 0, 0)
#define SD_DAT_HIGH IOWR(SD_DAT_BASE, 0, 1)
#define SD_CLK_LOW IOWR(SD_CLK_BASE, 0, 0)
#define SD_CLK_HIGH IOWR(SD_CLK_BASE, 0, 1)
// SD Card Input Read
#define SD_TEST_CMD IORD(SD_CMD_BASE, 0)
#define SD_TEST_DAT IORD(SD_DAT_BASE, 0)
//-------------------------------------
#define BYTE unsigned char
#define UINT16 unsigned int
#define UINT32 unsigned long
//-------------------------------------
void Ncr(void);
void Ncc(void);
BYTE response_R(BYTE);
BYTE send_cmd(BYTE *);
BYTE SD_read_lba(BYTE *,UINT32,UINT32);
BYTE SD_card_init(void);
//-------------------------------------
BYTE read_status;
BYTE response_buffer[20];
BYTE RCA[2];
BYTE cmd_buffer[5];
const BYTE cmd0[5] = {0x40,0x00,0x00,0x00,0x00};
const BYTE cmd55[5] = {0x77,0x00,0x00,0x00,0x00};
const BYTE cmd2[5] = {0x42,0x00,0x00,0x00,0x00};
const BYTE cmd3[5] = {0x43,0x00,0x00,0x00,0x00};
const BYTE cmd7[5] = {0x47,0x00,0x00,0x00,0x00};
const BYTE cmd9[5] = {0x49,0x00,0x00,0x00,0x00};
const BYTE cmd16[5] = {0x50,0x00,0x00,0x02,0x00};
const BYTE cmd17[5] = {0x51,0x00,0x00,0x00,0x00};
const BYTE acmd6[5] = {0x46,0x00,0x00,0x00,0x02};
const BYTE acmd41[5] = {0x69,0x0f,0xf0,0x00,0x00};
const BYTE acmd51[5] = {0x73,0x00,0x00,0x00,0x00};
//-------------------------------------
void Ncr(void)
{
SD_CMD_IN;
SD_CLK_LOW;
SD_CLK_HIGH;
SD_CLK_LOW;
SD_CLK_HIGH;
}
//-------------------------------------
void Ncc(void)
{
int i;
for(i=0;i<8;i++)
{
SD_CLK_LOW;
SD_CLK_HIGH;
}
}
//-------------------------------------
BYTE SD_card_init(void)
{
BYTE x,y;
SD_CMD_OUT;
SD_DAT_IN;
SD_CLK_HIGH;
SD_CMD_HIGH;
SD_DAT_LOW;
read_status=0;
for(x=0;x<40;x++)
Ncr();
for(x=0;x<5;x++)
cmd_buffer[x]=cmd0[x];
y = send_cmd(cmd_buffer);
do
{
for(x=0;x<40;x++);
Ncc();
for(x=0;x<5;x++)
cmd_buffer[x]=cmd55[x];
y = send_cmd(cmd_buffer);
Ncr();
if(response_R(1)>1) //response too long or crc error
return 1;
Ncc();
for(x=0;x<5;x++)
cmd_buffer[x]=acmd41[x];
y = send_cmd(cmd_buffer);
Ncr();
} while(response_R(3)==1);
Ncc();
for(x=0;x<5;x++)
cmd_buffer[x]=cmd2[x];
y = send_cmd(cmd_buffer);
Ncr();
if(response_R(2)>1)
return 1;
Ncc();
for(x=0;x<5;x++)
cmd_buffer[x]=cmd3[x];
y = send_cmd(cmd_buffer);
Ncr();
if(response_R(6)>1)
return 1;
RCA[0]=response_buffer[1];
RCA[1]=response_buffer[2];
Ncc();
for(x=0;x<5;x++)
cmd_buffer[x]=cmd9[x];
cmd_buffer[1] = RCA[0];
cmd_buffer[2] = RCA[1];
y = send_cmd(cmd_buffer);
Ncr();
if(response_R(2)>1)
return 1;
Ncc();
for(x=0;x<5;x++)
cmd_buffer[x]=cmd7[x];
cmd_buffer[1] = RCA[0];
cmd_buffer[2] = RCA[1];
y = send_cmd(cmd_buffer);
Ncr();
if(response_R(1)>1)
return 1;
Ncc();
for(x=0;x<5;x++)
cmd_buffer[x]=cmd16[x];
y = send_cmd(cmd_buffer);
Ncr();
if(response_R(1)>1)
return 1;
read_status =1; //sd card ready
return 0;
}
//-------------------------------------
BYTE SD_read_lba(BYTE *buff,UINT32 lba,UINT32 seccnt)
{
BYTE c=0;
UINT32 i,j;
lba+=101;
for(j=0;j<seccnt;j++)
{
{
Ncc();
cmd_buffer[0] = cmd17[0];
cmd_buffer[1] = (lba>>15)&0xff;
cmd_buffer[2] = (lba>>7)&0xff;
cmd_buffer[3] = (lba<<1)&0xff;
cmd_buffer[4] = 0;
lba++;
send_cmd(cmd_buffer);
Ncr();
}
while(1)
{
SD_CLK_LOW;
SD_CLK_HIGH;
if(!(SD_TEST_DAT))
break;
}
for(i=0;i<512;i++)
{
BYTE j;
for(j=0;j<8;j++)
{
SD_CLK_LOW;
SD_CLK_HIGH;
c <<= 1;
if(SD_TEST_DAT)
c |= 0x01;
}
*buff=c;
buff++;
}
for(i=0; i<16; i++)
{
SD_CLK_LOW;
SD_CLK_HIGH;
}
}
read_status = 1; //SD data next in
return 0;
}
//-------------------------------------
BYTE response_R(BYTE s)
{
BYTE a=0,b=0,c=0,r=0,crc=0;
BYTE i,j=6,k;
while(1)
{
SD_CLK_LOW;
SD_CLK_HIGH;
if(!(SD_TEST_CMD))
break;
if(crc++ >100)
return 2;
}
crc =0;
if(s == 2)
j = 17;
for(k=0; k<j; k++)
{
c = 0;
if(k > 0) //for crc culcar
b = response_buffer[k-1];
for(i=0; i<8; i++)
{
SD_CLK_LOW;
if(a > 0)
c <<= 1;
else
i++;
a++;
SD_CLK_HIGH;
if(SD_TEST_CMD)
c |= 0x01;
if(k > 0)
{
crc <<= 1;
if((crc ^ b) & 0x80)
crc ^= 0x09;
b <<= 1;
crc &= 0x7f;
}
}
if(s==3)
{
if( k==1 &&(!(c&0x80)))
r=1;
}
response_buffer[k] = c;
}
if(s==1 || s==6)
{
if(c != ((crc<<1)+1))
r=2;
}
return r;
}
//-------------------------------------
BYTE send_cmd(BYTE *in)
{
int i,j;
BYTE b,crc=0;
SD_CMD_OUT;
for(i=0; i < 5; i++)
{
b = in[i];
for(j=0; j<8; j++)
{
SD_CLK_LOW;
if(b&0x80)
SD_CMD_HIGH;
else
SD_CMD_LOW;
crc <<= 1;
SD_CLK_HIGH;
if((crc ^ b) & 0x80)
crc ^= 0x09;
b<<=1;
}
crc &= 0x7f;
}
crc =((crc<<1)|0x01);
b = crc;
for(j=0; j<8; j++)
{
SD_CLK_LOW;
if(crc&0x80)
SD_CMD_HIGH;
else
SD_CMD_LOW;
SD_CLK_HIGH;
crc<<=1;
}
return b;
}
//-------------------------------------
#endif
下面是主程序：
#include "basic_io.H"
#include "SD_Card.H"
#include "altera_avalon_pio_regs.H"
int main(void)
{
IOWR_ALTERA_AVALON_PIO_DATA(PIO_LED_BASE,1);
UINT16 i=0,Tmp1=0;
UINT32 j=720;
BYTE Buffer[512]={0};
usleep(500000);
//下面是SD卡播放wav音频的主要程序：
while(1)
{
SD_read_lba(Buffer,j,1);
while(i<512)
{
if(!IORD(AUDIO_0_BASE,0))
{
Tmp1 = (Buffer[i+1]<<8)|Buffer[i];
IOWR(AUDIO_0_BASE,0,Tmp1);
i+=2;
}
}
j++;
i=0;
}
}
为什么一执行到SD_read_lba(Buffer,j,1);这句就不出来了，好像陷入死循环了，而且Buffer里面的值全是0，并没有读出SD卡中的内容.
各位大侠帮帮忙，看一下！！！
[解决办法]
没仔细看，SD_card_init执行了吗，是否成功
[解决办法]
