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++)