[参考译文] MSP430F6747A：通过 SPI 接口与 eMMC MTFC8GAM 进行通信

我从未使用过 eMMC 卡、但使用过64MB MMC 卡。 我很久以前就这样做了。 它的协议与 SD 卡不同。 虽然与此类似、但除非专门编写了 SD 卡代码以回退到 MMC 设置、否则会失败。

MMC 的另一个不同之处在于、他们真正倾向于该多点位。 它们的输出始于集电极开路/漏极开路模式、因此 您必须配备一个上拉电阻器。

在查看我的一些旧 代码时、您应该会得到 CMD0的响应。

是的、我们在所有 eMMC 数据线路和 CMD 线路上都安装了上拉电阻器。

您的代码与我们的代码非常相似,我们的命令发送函数如下所示:

static void sdSpiSendCommand(unsigned char *res, unsigned bufferLength)
{
    unsigned tries = 0;
    unsigned char crc = 0;
    unsigned i;

    // sdCardCommand.command is the command id, 0 for init, 24 for write block etc
    // sdCardCommand.params is an uint32_t containing the command arguments
    const unsigned char rawCommand[5] = {
        0x40 | sdCardCommand.command,
        (sdCardCommand.params >> 24) & 0xFF,
        (sdCardCommand.params >> 16) & 0xFF,
        (sdCardCommand.params >> 8) & 0xFF,
        sdCardCommand.params & 0xFF};

    pinClear(SDCARD_CS); // Assert CS line to low level

    for (i = 0; i < sizeof(rawCommand); i++) {
        crc = crc7Tab[(crc << 1) ^ rawCommand[i]];

        // sdSSpiSendByte() both write a byte then read one which is returned
        sdSpiSendByte(rawCommand[i]);
    }

    sdSpiSendByte((crc << 1) | 0x01); // send CRC-7 followed by end bit

    do {
        if (++tries > SD_CMD_RESPONSE_TIMEOUT) {
            pinSet(SDCARD_CS);
            sdStatus |= SDCARD_CMD_TIMEOUT;
            return;
        }
        res[0] = sdSpiSendByte(0xFF);
    } while (res[0] == 0xFF); // There is a pull-up on DAT0, which means 0xFF is read if nothing is sent by the eMMC

    // Usually for MMC format, command response is 6 bytes
    for (i = 1; i < bufferLength; ++i) {
        res[i] = sdSpiSendByte(0xFF);
    }

    pinSet(SDCARD_CS);
}

When this function is called, it never reaches past the do-while loop, we're not getting anything back and we end up with an error.
On the oscilloscope the DAT0 line is constantly at logic level high due to the pull-up.

Do you see anything wrong with this code ? (This used to work with SD card)