[参考译文] MSP430F149：与 MMC SD 模块实现 SPI 通信 — CMD17（单块读取）、SD 卡以 0x00 进行响应（表示命令成功）、但后续的数据读取操作仅返回 0xFF 字节。

// Below is the code that handles the DISK IO 

#define CMD0    0x00 // spi mode
#define CMD1    0x01 // Initialization cmd
#define CMD8    0x08
#define CMD17   0x17
#define CMD24   0x24
#define ACMD41  0x41
#define CMD55   0x55
#define CMD58   0x58 // read ocr register to check the working voltage range

void spi_cs_high()
{
    P3OUT |= BIT0;
}

void spi_cs_low()
{
    P3OUT &=~BIT0;
}

uint8_t spi_transfer(uint8_t data) {

     while (!(IFG1 & UTXIFG0));  // Wait for TX buffer ready
     U0TXBUF = data;
     while (!(IFG1 & URXIFG0));  // Wait for TX complete
     return U0RXBUF; // Clear RX flag

}

// as some cards , delay the byte response after the cmd is being sent
uint8_t get_response()
{
    uint8_t i =0;
    uint8_t r ;

    for(;i<8;i++)
    {
        r = spi_transfer(0xFF);
        if(r != 0xFF)
            return r;
    }
    return r;
}


void send_cmd(uint8_t cmd,uint32_t arg)
{
    spi_transfer(0x40|cmd);
    spi_transfer(arg>>24);
    spi_transfer(arg>>16);
    spi_transfer(arg>>8);
    spi_transfer(arg);

    uint8_t crc = 0xFF;
    if (cmd == CMD0)
        crc = 0x95;
    else if (cmd == CMD8)
        crc = 0x87;
    spi_transfer(crc);
}

DSTATUS MMC_disk_initialize(void) {
        spi_cs_high();
        uint8_t i;
        for ( i = 0; i < 10; i++) spi_transfer(0xFF);  // 80 clock cycles

        // Switching from native mode to spi mode
        spi_cs_low();
        send_cmd(CMD0, 0); // sending cmd 0 to switch from native operating mode to spi mode ,
        //response should be r1 to indicate idle state
        P1OUT |= BIT3;
        while (1) // Wait for idle state
        {
            uint8_t res = spi_transfer(0xFF);

            if(res == 0x01)
            {
                break;
            }

        }

        spi_cs_high();
        spi_transfer(0xFF);

        P1OUT &= ~BIT3;

        spi_cs_low();
        send_cmd(CMD8, 0x000001AA);  // VHS=0x1 (2.7–3.6V), check pattern=0xAA

        uint8_t resp[4];
        uint8_t res ;

        while(1)
        {
             res = spi_transfer(0xFF);
            if(res == 0x01)
            {
                uint8_t i=0;
                for(;i<4;i++)
                {
                    resp[i]=spi_transfer(0xFF);
                }
                break;
            }
        }

        spi_cs_high();
        spi_transfer(0xFF);
//             r1 response              lower 12 bit to indicate sdc ver 2
        if (res!=0x01 || resp[2]!=0x01 || resp[3] != 0xAA) return 1;  // Invalid response → not SDHC

        // Initialization section
        P1OUT |= BIT3;


        uint16_t timeout = 5000;
        do {

                spi_cs_low();
                send_cmd(ACMD41, 0x40000000); // taking longer duration to initialize , sometimes able to initialize it.
                res = get_response(); // here res idle state should be removed leading to 0x00
                spi_cs_high();
                spi_transfer(0xFF);
          } while (res != 0x00 && --timeout);


        if (!timeout) return 2; // Timeout waiting for card to exit idle

        // --- CMD58 to read OCR ---
        uint8_t ocr[4];
        spi_cs_low();
        send_cmd(CMD58, 0);

        while(1)
        {
            res = spi_transfer(0xFF);
            if(res == 0x00)
            {
                for (i = 0; i < 4; i++) ocr[i] = spi_transfer(0xFF);
                break;
            }
        }


        spi_cs_high();
        spi_transfer(0xFF);

        // Check if card is SDHC/SDXC by checking CCS bit (bit 30)
        if (ocr[0] & 0x40) {
            return 0; // SDHC card initialized successfully
        } else {
            return 3; // Not SDHC (maybe SDSC)
        }

}

DRESULT MMC_disk_read(unsigned char *buff, uint32_t sector,uint16_t count) {
    if (count != 1) return RES_PARERR;

    spi_cs_low();
    send_cmd(CMD17, sector);

    uint8_t r1;
    r1 = get_response();
    if(r1 !=0)
    {
       spi_cs_high();
       return RES_ERROR;
    }

    uint8_t res=0xFF;
    while (res==0xFF)    // Wait for data token
    {
       res = spi_transfer(0xFF);
    }

    uint16_t i;
    for (i = 0; i < 512; i++) {
        buff[i] = spi_transfer(0xFF);
    }

    spi_transfer(0xFF);  // Dummy CRC
    spi_transfer(0xFF);
    spi_cs_high();
    spi_transfer(0xFF);  // Ncr

    return RES_OK;
}

David Schultz 上面的代码逻辑类似于我的描述,请看一下,如果需要任何其他信息,请告诉我

这是不对的。 “ send_cmd (ACMD41、0x40000000)；“

您必须发送 CMD55 才能获取 ACMD 操作。 这里只是 CMD41。 实际上、这也很混乱：

#define ACMD41  0x41
#define CMD55   0x55
#define CMD58   0x58 // read ocr register to check the working voltage range

        uint16_t timeout = 5000;
        do {
                spi_cs_low();
                send_cmd(CMD55, 0); // Send CMD55 before ACMD41
                res = get_response(); // Get response for CMD55
                spi_cs_high();
                spi_transfer(0xFF);

                spi_cs_low();
                send_cmd(CMD41, 0x40000000); // Send CMD41 with HCS bit set
                res = get_response(); // Get response for CMD41
                spi_cs_high();
                spi_transfer(0xFF);

             } while (res != 0x00 && --timeout);

David Schultz 。正如您所指出的、我更新了逻辑、在 ACMD41 之前发送 CMD55。 但观察 0x05（对于 CMD55）和 0x00（对于 CMD41）的响应  

您是否修复了“#define CMD55  0x55“等问题？

是的、下面是更新的宏  

#define CMD0    0x00 // spi mode
#define CMD1    0x01 // Initialization cmd
#define CMD8    0x08
#define CMD17   0x17
#define CMD24   0x24
#define CMD41   0x41
#define CMD55   0x55
#define CMD58   0x58 

对于 CMD55、我是否需要更改为任何其他值、 在通过 SPI 发送 cmd 时、我正在使用 0x40 执行或操作 cmd

不是。 你让它变得更糟。

0x55 与 0x15 相同。 又名 CMD21。  

你能详细说明并指出我正确的方向,因为我没有得到什么需要应用的变化. 到目前为止、我要介绍  的是 elm-chan.org/.../mmc_e.html 资源。  

你似乎不理解基数 16 和基数 10 之间的区别。  

甚至是简单的按位或运算。

我无法帮您解决这个问题。

Diego Abad Sajamin 感谢您的澄清。