10 rtthread SDIO SD卡驱动CMD指令发送错误

发布于 2023-01-25 14:57:28 浏览：1169 订阅该版

最近在看rtthread的SDIO通用设备驱动，发现对于SD卡的驱动存在一些问题，发出来与大家交流下：

针对目前大多数的V2.0的SD卡，关于SD卡的识别，流程大致如下：
1. 首先发送CMD0，进入空闲
2. 之后发送CMD8，查询接口条件，电压等级等
3. 之后发送ACMD41获取OCR以及卡容量，（我发现的问题就出现在这里）
更细节的流程可以参考SD V2.0协议，或查看此链接所总结的：https://blog.csdn.net/qq_43332314/article/details/128592423

问题一：ACMD41此指令为ACMD指令，ACMD指令的识别是需要先发送一个CMD55指令，之后再发送CMD41的，不过我看源码这里是直接发送的CMD41，那不就有问题了吗？

问题二：关于mmcsd_detect函数的理解，`err = mmcsd_send_app_op_cond(host, 0, &ocr);`发送的是CMD41，针对V2.0的卡的识别，`err = mmc_send_op_cond(host, 0, &ocr);`针对的是MMC卡的识别，
`err = sdio_io_send_op_cond(host, 0, &ocr);`发送的是CMD5，这是针对V1.0的卡的识别吗？还是针对IO卡？

对应文件在mmcsd_core.c中，源码如下：
```c

void mmcsd_detect(void *param)
{
    struct rt_mmcsd_host *host;
    rt_uint32_t  ocr;
    rt_int32_t  err;

while (1)
    {
        if (rt_mb_recv(&mmcsd_detect_mb, (rt_ubase_t *)&host, RT_WAITING_FOREVER) == RT_EOK)
        {
            if (host->card == RT_NULL)
            {
                mmcsd_host_lock(host);
                mmcsd_power_up(host);
                mmcsd_go_idle(host);

mmcsd_send_if_cond(host, host->valid_ocr);

err = sdio_io_send_op_cond(host, 0, &ocr);
                if (!err)
                {
                    if (init_sdio(host, ocr))
                        mmcsd_power_off(host);
                    mmcsd_host_unlock(host);
                    continue;
                }

/*
                 * detect SD card
                 */
                err = mmcsd_send_app_op_cond(host, 0, &ocr);
                if (!err)
                {
                    if (init_sd(host, ocr))
                        mmcsd_power_off(host);
                    mmcsd_host_unlock(host);
                    rt_mb_send(&mmcsd_hotpluge_mb, (rt_uint32_t)host);
                    continue;
                }

/*
                 * detect mmc card
                 */
                err = mmc_send_op_cond(host, 0, &ocr);
                if (!err)
                {
                    if (init_mmc(host, ocr))
                        mmcsd_power_off(host);
                    mmcsd_host_unlock(host);
                    rt_mb_send(&mmcsd_hotpluge_mb, (rt_uint32_t)host);
                    continue;
                }
                mmcsd_host_unlock(host);
            }
            else
            {
                /* card removed */
                mmcsd_host_lock(host);
                if (host->card->sdio_function_num != 0)
                {
                    LOG_W("unsupport sdio card plug out!");
                }
                else
                {
                    rt_mmcsd_blk_remove(host->card);
                    rt_free(host->card);

host->card = RT_NULL;
                }
                mmcsd_host_unlock(host);
                rt_mb_send(&mmcsd_hotpluge_mb, (rt_uint32_t)host);
            }
        }
    }
```

对应宏定义如下：

![screenshot_image.png](https://oss-club.rt-thread.org/uploads/20230125/dae9375f2fc17319a2a6bbee8af3f67f.png.webp)

ACMD41指令描述如下：

![screenshot_image.png](https://oss-club.rt-thread.org/uploads/20230125/63d3a16c632c797d45c86e9e190a698b.png.webp)