C - 在 SPI 模式下初始化 SD 卡，始终读回 0xFF

Question

我正在尝试使用 Cypress PSoC 5 初始化 2GB SanDisk SD 卡SPI接口。我正在使用 FatFs - 通用 FAT 文件系统模块中的示例位敲击代码。我已经在逻辑分析仪上分析了接口（请参阅 ）。问题是 SD 卡的数据输出线始终为高电平，我应该从卡初始化命令中返回 0x01。然而，SD 卡在 PC 上读取良好。我正在使用的代码如下，问题可能是什么？

我正在使用 http://ucontroller.com/documentation/SDCardDoc.html。

/*------------------------------------------------------------------------/
/  Bitbanging MMCv3/SDv1/SDv2 (in SPI mode) control module
/-------------------------------------------------------------------------/
/
/  Copyright (C) 2010, ChaN, all right reserved.
/
/ * This software is a free software and there is NO WARRANTY.
/ * No restriction on use. You can use, modify and redistribute it for
/   personal, non-profit or commercial products UNDER YOUR RESPONSIBILITY.
/ * Redistributions of source code must retain the above copyright notice.
/
/--------------------------------------------------------------------------/
 Features and Limitations:

 * Very Easy to Port
   It uses only 4-6 bit of GPIO port. No interrupt, no SPI port is used.

 * Platform Independent
   You need to modify only a few macros to control GPIO ports.

 * Low Speed
   The data transfer rate will be several times slower than hardware SPI.

 * No Media Change Detection
   Application program must re-mount the volume after media change or it
   results a hard error.

/-------------------------------------------------------------------------*/

#include <device.h>
#include "diskio.h"        /* Common include file for FatFs and disk I/O layer */


/*-------------------------------------------------------------------------*/
/* Platform dependent macros and functions needed to be modified           */
/*-------------------------------------------------------------------------*/

#include <device.h>                /* Include device specific declareation file here */

#define INIT_PORT()   /* Initialize MMC control port (CS/CLK/DI:output, DO/WP/INS:input) */
#define DLY_US(n)      CyDelayUs(n)    /* Delay n microseconds */

#define CLK_DELAY()   CyDelayUs(1)
#define CS_H()        CyPins_SetPin(ss_0)        /* Set MMC CS "high" */
#define CS_L()        CyPins_ClearPin(ss_0)      /* Set MMC CS "low" */
#define CK_H()        CyPins_SetPin(clk_0)       /* Set MMC SCLK "high" */
#define CK_L()        CyPins_ClearPin(clk_0)     /* Set MMC SCLK "low" */
#define DI_H()        CyPins_SetPin(spiout_0)    /* Set MMC DI "high" */
#define DI_L()        CyPins_ClearPin(spiout_0)  /* Set MMC DI "low" */
#define DO            CyPins_ReadPin(spiin_0)    /* Get MMC DO value (high:true, low:false) */

#define    INS        (1)            /* Card is inserted (yes:true, no:false, default:true) */
#define    WP         (0)            /* Card is write protected (yes:true, no:false, default:false) */



/*--------------------------------------------------------------------------

   Module Private Functions

---------------------------------------------------------------------------*/

/* MMC/SD command (SPI mode) */
#define CMD0      (0)        /* GO_IDLE_STATE */
#define CMD1      (1)        /* SEND_OP_COND */
#define ACMD41    (0x80+41)  /* SEND_OP_COND (SDC) */
#define CMD8      (8)        /* SEND_IF_COND */
#define CMD9      (9)        /* SEND_CSD */
#define CMD10    (10)        /* SEND_CID */
#define CMD12    (12)        /* STOP_TRANSMISSION */
#define ACMD13   (0x80+13)   /* SD_STATUS (SDC) */
#define CMD16    (16)        /* SET_BLOCKLEN */
#define CMD17    (17)        /* READ_SINGLE_BLOCK */
#define CMD18    (18)        /* READ_MULTIPLE_BLOCK */
#define CMD23    (23)        /* SET_BLOCK_COUNT */
#define ACMD23   (0x80+23)   /* SET_WR_BLK_ERASE_COUNT (SDC) */
#define CMD24    (24)        /* WRITE_BLOCK */
#define CMD25    (25)        /* WRITE_MULTIPLE_BLOCK */
#define CMD41    (41)        /* SEND_OP_COND (ACMD) */
#define CMD55    (55)        /* APP_CMD */
#define CMD58    (58)        /* READ_OCR */

/* Card type flags (CardType) */
#define CT_MMC        0x01            /* MMC ver 3 */
#define CT_SD1        0x02            /* SD ver 1 */
#define CT_SD2        0x04            /* SD ver 2 */
#define CT_SDC        (CT_SD1|CT_SD2) /* SD */
#define CT_BLOCK      0x08            /* Block addressing */


static
DSTATUS Stat = STA_NOINIT;    /* Disk status */

static
BYTE CardType;            /* b0:MMC, b1:SDv1, b2:SDv2, b3:Block addressing */

static char buf[80];

/*-----------------------------------------------------------------------*/
/* Transmit bytes to the MMC (bitbanging)                                */
/*-----------------------------------------------------------------------*/
static
void xmit_mmc (
    const BYTE* buff,    /* Data to be sent */
    UINT bc              /* Number of bytes to send */
)
{
    BYTE d;

    do {
        d = *buff++;    /* Get a byte to be sent */
        if (d & 0x80) DI_H(); else DI_L();    /* bit7 */
        CK_H(); CLK_DELAY(); CK_L(); CLK_DELAY();
        if (d & 0x40) DI_H(); else DI_L();    /* bit6 */
        CK_H(); CLK_DELAY(); CK_L(); CLK_DELAY();
        if (d & 0x20) DI_H(); else DI_L();    /* bit5 */
        CK_H(); CLK_DELAY(); CK_L(); CLK_DELAY();
        if (d & 0x10) DI_H(); else DI_L();    /* bit4 */
        CK_H(); CLK_DELAY(); CK_L(); CLK_DELAY();
        if (d & 0x08) DI_H(); else DI_L();    /* bit3 */
        CK_H(); CLK_DELAY(); CK_L(); CLK_DELAY();
        if (d & 0x04) DI_H(); else DI_L();    /* bit2 */
        CK_H(); CLK_DELAY(); CK_L(); CLK_DELAY();
        if (d & 0x02) DI_H(); else DI_L();    /* bit1 */
        CK_H(); CLK_DELAY(); CK_L(); CLK_DELAY();
        if (d & 0x01) DI_H(); else DI_L();    /* bit0 */
        CK_H(); CLK_DELAY(); CK_L(); CLK_DELAY();
        DLY_US(10);
        //snprintf(buf, sizeof buf, "sent 0x%02x\r\n", d);
        //UART_1_PutString(buf);
    } while (--bc);
}


/*-----------------------------------------------------------------------*/
/* Receive bytes from the MMC (bitbanging)                               */
/*-----------------------------------------------------------------------*/
static
void rcvr_mmc (
    BYTE *buff,    /* Pointer to read buffer */
    UINT bc        /* Number of bytes to receive */
)
{
    BYTE r;

    DI_H();    /* Send 0xFF */

    do {
        r = 0;   if (DO) r++;    /* bit7 */
        CK_H(); CLK_DELAY(); CK_L(); CLK_DELAY();
        r <<= 1; if (DO) r++;    /* bit6 */
        CK_H(); CLK_DELAY(); CK_L(); CLK_DELAY();
        r <<= 1; if (DO) r++;    /* bit5 */
        CK_H(); CLK_DELAY(); CK_L(); CLK_DELAY();
        r <<= 1; if (DO) r++;    /* bit4 */
        CK_H(); CLK_DELAY(); CK_L(); CLK_DELAY();
        r <<= 1; if (DO) r++;    /* bit3 */
        CK_H(); CLK_DELAY(); CK_L(); CLK_DELAY();
        r <<= 1; if (DO) r++;    /* bit2 */
        CK_H(); CLK_DELAY(); CK_L(); CLK_DELAY();
        r <<= 1; if (DO) r++;    /* bit1 */
        CK_H(); CLK_DELAY(); CK_L(); CLK_DELAY();
        r <<= 1; if (DO) r++;    /* bit0 */
        CK_H(); CLK_DELAY(); CK_L(); CLK_DELAY();
        *buff++ = r;            /* Store a received byte */
        DLY_US(10);
        //snprintf(buf, sizeof buf, "received 0x%02x\r\n", r);
        //UART_1_PutString(buf);
    } while (--bc);
}


/*-----------------------------------------------------------------------*/
/* Wait for card ready                                                   */
/*-----------------------------------------------------------------------*/
static
int wait_ready (void)    /* 1:OK, 0:Timeout */
{
    BYTE d;
    UINT tmr;

    for (tmr = 5000; tmr; tmr--) {    /* Wait for ready in timeout of 500ms */
        rcvr_mmc(&d, 1);
        if (d == 0xFF) return 1;
        DLY_US(100);
    }
    return 0;
}


/*-----------------------------------------------------------------------*/
/* Deselect the card and release SPI bus                                 */
/*-----------------------------------------------------------------------*/
static
void deselect (void)
{
    BYTE d;

    CS_H();
    rcvr_mmc(&d, 1);
}


/*-----------------------------------------------------------------------*/
/* Select the card and wait for ready                                    */
/*-----------------------------------------------------------------------*/
static
int select (void)    /* 1:OK, 0:Timeout */
{
    CS_L();
    if (!wait_ready()) {
        deselect();
        return 0;
    }
    return 1;
}


/*-----------------------------------------------------------------------*/
/* Receive a data packet from MMC                                        */
/*-----------------------------------------------------------------------*/
static
int rcvr_datablock (    /* 1:OK, 0:Failed */
    BYTE *buff,         /* Data buffer to store received data */
    UINT btr            /* Byte count */
)
{
    BYTE d[2];
    UINT tmr;

    for (tmr = 1000; tmr; tmr--) {  /* Wait for data packet in timeout of 100ms */
        rcvr_mmc(d, 1);
        if (d[0] != 0xFF) break;
        DLY_US(100);
    }
    if (d[0] != 0xFE)
        return 0;                   /* If not valid data token, retutn with error */

    rcvr_mmc(buff, btr);            /* Receive the data block into buffer */
    rcvr_mmc(d, 2);                 /* Discard CRC */

    return 1;                       /* Return with success */
}


/*-----------------------------------------------------------------------*/
/* Send a data packet to MMC                                             */
/*-----------------------------------------------------------------------*/
static
int xmit_datablock (    /* 1:OK, 0:Failed */
    const BYTE *buff,   /* 512 byte data block to be transmitted */
    BYTE token          /* Data/Stop token */
)
{
    BYTE d[2];

    if (!wait_ready())
        return 0;

    d[0] = token;
    xmit_mmc(d, 1);                /* Transmit a token */
    if (token != 0xFD) {           /* Is it data token? */
        xmit_mmc(buff, 512);       /* Transmit the 512 byte data block to MMC */
        rcvr_mmc(d, 2);            /* Dummy CRC (FF,FF) */
        rcvr_mmc(d, 1);            /* Receive data response */
        if ((d[0] & 0x1F) != 0x05) /* If not accepted, return with error */
            return 0;
    }
    return 1;
}


/*-----------------------------------------------------------------------*/
/* Send a command packet to MMC                                          */
/*-----------------------------------------------------------------------*/
static
BYTE send_cmd (        /* Returns command response (bit7==1:Send failed)*/
    BYTE cmd,          /* Command byte */
    DWORD arg          /* Argument */
)
{
    BYTE n, d, buf[6];


    if (cmd & 0x80) {    /* ACMD<n> is the command sequense of CMD55-CMD<n> */
        cmd &= 0x7F;
        n = send_cmd(CMD55, 0);
        if (n > 1) return n;
    }

    /* Select the card and wait for ready */
    deselect();
    if (!select()) {
        return 0xFF;
    }

    /* Send a command packet */
    buf[0] = 0x40 | cmd;            /* Start + Command index */
    buf[1] = (BYTE)(arg >> 24);     /* Argument[31..24] */
    buf[2] = (BYTE)(arg >> 16);     /* Argument[23..16] */
    buf[3] = (BYTE)(arg >> 8);      /* Argument[15..8] */
    buf[4] = (BYTE)arg;             /* Argument[7..0] */
    n = 0x01;                       /* Dummy CRC + Stop */
    if (cmd == CMD0)
        n = 0x95;      /* (valid CRC for CMD0(0)) */
    if (cmd == CMD8)
        n = 0x87;      /* (valid CRC for CMD8(0x1AA)) */
    buf[5] = n;
    xmit_mmc(buf, 6);

    /* Receive command response */
    if (cmd == CMD12)
        rcvr_mmc(&d, 1);    /* Skip a stuff byte when stop reading */
    n = 10;                 /* Wait for a valid response in timeout of 10 attempts */
    do
        rcvr_mmc(&d, 1);
    while ((d & 0x80) && --n);

    return d;            /* Return with the response value */
}


/*--------------------------------------------------------------------------

   Public Functions

---------------------------------------------------------------------------*/

/*-----------------------------------------------------------------------*/
/* Get Disk Status                                                       */
/*-----------------------------------------------------------------------*/
DSTATUS disk_status (
    BYTE drv            /* Drive number (0) */
)
{
    DSTATUS s = Stat;

    if (drv || !INS) {
        s = STA_NODISK | STA_NOINIT;
    } else {
        s &= ~STA_NODISK;
        if (WP)
            s |= STA_PROTECT;
        else
            s &= ~STA_PROTECT;
    }
    Stat = s;

    return s;
}


/*-----------------------------------------------------------------------*/
/* Initialize Disk Drive                                                 */
/*-----------------------------------------------------------------------*/
DSTATUS disk_initialize (
    BYTE drv        /* Physical drive nmuber (0) */
)
{
    BYTE n, ty, cmd, buf[4];
    UINT tmr;
    DSTATUS s;

    INIT_PORT();                /* Initialize control port */

    s = disk_status(drv);        /* Check if card is in the socket */
    if (s & STA_NODISK) return s;

    CS_H();

    for (n = 10; n; n--) rcvr_mmc(buf, 1);    /* 80 dummy clocks */

    ty = 0;
    if (send_cmd(CMD0, 0) == 1) {            /* Enter Idle state */
        if (send_cmd(CMD8, 0x1AA) == 1) {    /* SDv2? */
            rcvr_mmc(buf, 4);                            /* Get trailing return value of R7 resp */
            if (buf[2] == 0x01 && buf[3] == 0xAA) {        /* The card can work at vdd range of 2.7-3.6V */
                for (tmr = 1000; tmr; tmr--) {            /* Wait for leaving idle state (ACMD41 with HCS bit) */
                    if (send_cmd(ACMD41, 1UL << 30) == 0) break;
                    DLY_US(1000);
                }
                if (tmr && send_cmd(CMD58, 0) == 0) {    /* Check CCS bit in the OCR */
                    rcvr_mmc(buf, 4);
                    ty = (buf[0] & 0x40) ? CT_SD2 | CT_BLOCK : CT_SD2;    /* SDv2 */
                }
            }
        } else {                            /* SDv1 or MMCv3 */
            if (send_cmd(ACMD41, 0) <= 1)     {
                ty = CT_SD1; cmd = ACMD41;    /* SDv1 */
            } else {
                ty = CT_MMC; cmd = CMD1;    /* MMCv3 */
            }
            for (tmr = 1000; tmr; tmr--) {            /* Wait for leaving idle state */
                if (send_cmd(ACMD41, 0) == 0) break;
                DLY_US(1000);
            }
            if (!tmr || send_cmd(CMD16, 512) != 0)    /* Set R/W block length to 512 */
                ty = 0;
        }
    }
    else {
        UART_1_PutString("send CMD 0 failed");
    }
    CardType = ty;
    if (ty)        /* Initialization succeded */
        s &= ~STA_NOINIT;
    else        /* Initialization failed */
        s |= STA_NOINIT;
    Stat = s;

    deselect();

    return s;
}


/*-----------------------------------------------------------------------*/
/* Read Sector(s)                                                        */
/*-----------------------------------------------------------------------*/
DRESULT disk_read (
    BYTE drv,            /* Physical drive nmuber (0) */
    BYTE *buff,          /* Pointer to the data buffer to store read data */
    DWORD sector,        /* Start sector number (LBA) */
    BYTE count           /* Sector count (1..128) */
)
{
    DSTATUS s;

    s = disk_status(drv);
    if (s & STA_NOINIT) return RES_NOTRDY;
    if (!count) return RES_PARERR;
    if (!(CardType & CT_BLOCK)) sector *= 512;    /* Convert LBA to byte address if needed */

    if (count == 1) {    /* Single block read */
        if ((send_cmd(CMD17, sector) == 0)    /* READ_SINGLE_BLOCK */
            && rcvr_datablock(buff, 512))
            count = 0;
    }
    else {                /* Multiple block read */
        if (send_cmd(CMD18, sector) == 0) {    /* READ_MULTIPLE_BLOCK */
            do {
                if (!rcvr_datablock(buff, 512)) break;
                buff += 512;
            } while (--count);
            send_cmd(CMD12, 0);                /* STOP_TRANSMISSION */
        }
    }
    deselect();
    return count ? RES_ERROR : RES_OK;
}


/*-----------------------------------------------------------------------*/
/* Write Sector(s)                                                       */
/*-----------------------------------------------------------------------*/
DRESULT disk_write (
    BYTE drv,            /* Physical drive nmuber (0) */
    const BYTE *buff,    /* Pointer to the data to be written */
    DWORD sector,        /* Start sector number (LBA) */
    BYTE count            /* Sector count (1..128) */
)
{
    DSTATUS s;

    s = disk_status(drv);
    if (s & STA_NOINIT) return RES_NOTRDY;
    if (s & STA_PROTECT) return RES_WRPRT;
    if (!count) return RES_PARERR;
    if (!(CardType & CT_BLOCK)) sector *= 512;    /* Convert LBA to byte address if needed */

    if (count == 1) {    /* Single block write */
        if ((send_cmd(CMD24, sector) == 0)    /* WRITE_BLOCK */
            && xmit_datablock(buff, 0xFE))
            count = 0;
    }
    else {                /* Multiple block write */
        if (CardType & CT_SDC) send_cmd(ACMD23, count);
        if (send_cmd(CMD25, sector) == 0) {    /* WRITE_MULTIPLE_BLOCK */
            do {
                if (!xmit_datablock(buff, 0xFC)) break;
                buff += 512;
            } while (--count);
            if (!xmit_datablock(0, 0xFD))    /* STOP_TRAN token */
                count = 1;
        }
    }
    deselect();
    return count ? RES_ERROR : RES_OK;
}


/*-----------------------------------------------------------------------*/
/* Miscellaneous Functions                                               */
/*-----------------------------------------------------------------------*/
DRESULT disk_ioctl (
    BYTE drv,        /* Physical drive nmuber (0) */
    BYTE ctrl,        /* Control code */
    void *buff        /* Buffer to send/receive control data */
)
{
    DRESULT res;
    BYTE n, csd[16];
    WORD cs;

    if (disk_status(drv) & STA_NOINIT)   /* Check if card is in the socket */
        return RES_NOTRDY;

    res = RES_ERROR;
    switch (ctrl) {
        case CTRL_SYNC :        /* Make sure that no pending write process */
            if (select()) {
                deselect();
                res = RES_OK;
            }
            break;

        case GET_SECTOR_COUNT :    /* Get number of sectors on the disk (DWORD) */
            if ((send_cmd(CMD9, 0) == 0) && rcvr_datablock(csd, 16)) {
                if ((csd[0] >> 6) == 1) {    /* SDC ver 2.00 */
                    cs= csd[9] + ((WORD)csd[8] << 8) + 1;
                    *(DWORD*)buff = (DWORD)cs << 10;
                } else {                    /* SDC ver 1.XX or MMC */
                    n = (csd[5] & 15) + ((csd[10] & 128) >> 7) + ((csd[9] & 3) << 1) + 2;
                    cs = (csd[8] >> 6) + ((WORD)csd[7] << 2) + ((WORD)(csd[6] & 3) << 10) + 1;
                    *(DWORD*)buff = (DWORD)cs << (n - 9);
                }
                res = RES_OK;
            }
            break;

        case GET_BLOCK_SIZE :    /* Get erase block size in unit of sector (DWORD) */
            *(DWORD*)buff = 128;
            res = RES_OK;
            break;

        default:
            res = RES_PARERR;
    }
    deselect();
    return res;
}

Answer 1

一般情况下，同一接口线上连接多张SD卡时，可以放置上拉电阻。特别是，当您取消选择并选择另一张卡时，信号 DI、DO 和 CLK 会变为浮动。

否则，我可以想象它也会对主机和从机（在本例中为 microSD 卡）之间的轨道长度产生影响。

我在互联网上找到的许多示例电路中都看到了上拉电阻。

Answer 2

根据三星microSD卡的数据表，DO信号（SPI模式）被定义为推挽输出。这意味着该信号不需要外部上拉电阻。