最近收到了一片国产工业级SD NAND，可以替代SD卡，容量大，贴片封装，非常适合做飞控"黑匣子"。

不用写驱动程序自带坏块管理的NAND Flash（贴片式TF卡），尺寸小巧，简单易用，兼容性强，稳定可靠，固件可定制，LGA-8封装，标准SDIO接口，兼容SPI/SD接口，兼容各大MCU平台，可替代普通TF卡/SD卡，尺寸6x8mm毫米，内置SLC晶圆擦写寿命10万次，通过1万次随机掉电测试耐高低温，支持工业级温度-40°~+85°，机贴手贴都非常方便，速度级别Class10（读取速度23.5MB/S写入速度12.3MB/S）标准的SD 2.0协议使得用户可以直接移植标准驱动代码，省去了驱动代码编程环节。支持TF卡启动的SOC都可以用SD NAND，厂商提供了STM32参考例程及原厂技术支持，主流容量：128MB/512MB/2GB/4GB/8GB，比TF卡稳定，比eMMC便宜。

飞控板上ESP32C3的SDIO接口暂时用不了，只能先用SPI接口驱动。

评估板做了个micro SD卡的接口，方便直接插到带卡槽的开发板上进行调试。

ESP32C3的SPI接口是硬件SPI，支持DMA，速度应该还可以，但是我用杜邦线连接的，肯定会影响信号质量，估计时钟很难跑到50MHz了。

接线：

编写测试程序：

 

 

#include

#include

#include

#include "esp_vfs_fat.h"

#include "sdmmc_cmd.h"

 

#define EXAMPLE_MAX_CHAR_SIZE 64

 

static const char *TAG = "example";

 

#define MOUNT_POINT "/sdcard"

 

// Pin assignments can be set in menuconfig, see "SD SPI Example Configuration" menu.

// You can also change the pin assignments here by changing the following 4 lines.

#define PIN_NUM_MISO CONFIG_EXAMPLE_PIN_MISO

#define PIN_NUM_MOSI CONFIG_EXAMPLE_PIN_MOSI

#define PIN_NUM_CLK CONFIG_EXAMPLE_PIN_CLK

#define PIN_NUM_CS CONFIG_EXAMPLE_PIN_CS

 

static esp_err_t s_example_write_file(const char *path, char *data)

{

ESP_LOGI(TAG, "Opening file %s", path);

FILE *f = fopen(path, "w");

if (f == NULL) {

ESP_LOGE(TAG, "Failed to open file for writing");

return ESP_FAIL;

}

fprintf(f, data);

fclose(f);

ESP_LOGI(TAG, "File written");

 

return ESP_OK;

}

 

static esp_err_t s_example_read_file(const char *path)

{

ESP_LOGI(TAG, "Reading file %s", path);

FILE *f = fopen(path, "r");

if (f == NULL) {

ESP_LOGE(TAG, "Failed to open file for reading");

return ESP_FAIL;

}

char line[EXAMPLE_MAX_CHAR_SIZE];

fgets(line, sizeof(line), f);

fclose(f);

 

// strip newline

char *pos = strchr(line, '\n');

if (pos) {

*pos = '\0';

}

ESP_LOGI(TAG, "Read from file: '%s'", line);

 

return ESP_OK;

}

 

void app_main(void)

{

esp_err_t ret;

 

// Options for mounting the filesystem.

// If format_if_mount_failed is set to true, SD card will be partitioned and

// formatted in case when mounting fails.

esp_vfs_fat_sdmmc_mount_config_t mount_config = {

#ifdef CONFIG_EXAMPLE_FORMAT_IF_MOUNT_FAILED

.format_if_mount_failed = true,

#else

.format_if_mount_failed = false,

#endif // EXAMPLE_FORMAT_IF_MOUNT_FAILED

.max_files = 5,

.allocation_unit_size = 16 * 1024

};

sdmmc_card_t *card;

const char mount_point[] = MOUNT_POINT;

ESP_LOGI(TAG, "Initializing SD card");

 

// Use settings defined above to initialize SD card and mount FAT filesystem.

// Note: esp_vfs_fat_sdmmc/sdspi_mount is all-in-one convenience functions.

// Please check its source code and implement error recovery when developing

// production applications.

ESP_LOGI(TAG, "Using SPI peripheral");

 

// By default, SD card frequency is initialized to SDMMC_FREQ_DEFAULT (20MHz)

// For setting a specific frequency, use host.max_freq_khz (range 400kHz - 20MHz for SDSPI)

// Example: for fixed frequency of 10MHz, use host.max_freq_khz = 10000;

sdmmc_host_t host = SDSPI_HOST_DEFAULT();

 

spi_bus_config_t bus_cfg = {

.mosi_io_num = PIN_NUM_MOSI,

.miso_io_num = PIN_NUM_MISO,

.sclk_io_num = PIN_NUM_CLK,

.quadwp_io_num = -1,

.quadhd_io_num = -1,

.max_transfer_sz = 4000,

};

ret = spi_bus_initialize(host.slot, &bus_cfg, SDSPI_DEFAULT_DMA);

if (ret != ESP_OK) {

ESP_LOGE(TAG, "Failed to initialize bus.");

return;

}

 

// This initializes the slot without card detect (CD) and write protect (WP) signals.

// Modify slot_config.gpio_cd and slot_config.gpio_wp if your board has these signals.

sdspi_device_config_t slot_config = SDSPI_DEVICE_CONFIG_DEFAULT();

slot_config.gpio_cs = PIN_NUM_CS;

slot_config.host_id = host.slot;

 

ESP_LOGI(TAG, "Mounting filesystem");

ret = esp_vfs_fat_sdspi_mount(mount_point, &host, &slot_config, &mount_config, &card);

 

if (ret != ESP_OK) {

if (ret == ESP_FAIL) {

ESP_LOGE(TAG, "Failed to mount filesystem. "

"If you want the card to be formatted, set the CONFIG_EXAMPLE_FORMAT_IF_MOUNT_FAILED menuconfig option.");

} else {

ESP_LOGE(TAG, "Failed to initialize the card (%s). "

"Make sure SD card lines have pull-up resistors in place.", esp_err_to_name(ret));

}

return;

}

ESP_LOGI(TAG, "Filesystem mounted");

 

// Card has been initialized, print its properties

sdmmc_card_print_info(stdout, card);

 

// Use POSIX and C standard library functions to work with files.

 

// First create a file.

const char *file_hello = MOUNT_POINT"/hello.txt";

char data[EXAMPLE_MAX_CHAR_SIZE];

snprintf(data, EXAMPLE_MAX_CHAR_SIZE, "%s %s!\n", "Hello", card->cid.name);

ret = s_example_write_file(file_hello, data);

if (ret != ESP_OK) {

return;

}

 

const char *file_foo = MOUNT_POINT"/foo.txt";

 

// Check if destination file exists before renaming

struct stat st;

if (stat(file_foo, &st) == 0) {

// Delete it if it exists

unlink(file_foo);

}

 

// Rename original file

ESP_LOGI(TAG, "Renaming file %s to %s", file_hello, file_foo);

if (rename(file_hello, file_foo) != 0) {

ESP_LOGE(TAG, "Rename failed");

return;

}

 

ret = s_example_read_file(file_foo);

if (ret != ESP_OK) {

return;

}

 

// Format FATFS

ret = esp_vfs_fat_sdcard_format(mount_point, card);

if (ret != ESP_OK) {

ESP_LOGE(TAG, "Failed to format FATFS (%s)", esp_err_to_name(ret));

return;

}

 

if (stat(file_foo, &st) == 0) {

ESP_LOGI(TAG, "file still exists");

return;

} else {

ESP_LOGI(TAG, "file doesnt exist, format done");

}

 

const char *file_nihao = MOUNT_POINT"/nihao.txt";

memset(data, 0, EXAMPLE_MAX_CHAR_SIZE);

snprintf(data, EXAMPLE_MAX_CHAR_SIZE, "%s %s!\n", "Nihao", card->cid.name);

ret = s_example_write_file(file_nihao, data);

if (ret != ESP_OK) {

return;

}

 

//Open file for reading

ret = s_example_read_file(file_nihao);

if (ret != ESP_OK) {

return;

}

 

// All done, unmount partition and disable SPI peripheral

esp_vfs_fat_sdcard_unmount(mount_point, card);

ESP_LOGI(TAG, "Card unmounted");

 

//deinitialize the bus after all devices are removed

spi_bus_free(host.slot);

}

 

这段代码是使用SPI（串行外设接口）与SD卡进行通信。它展示了如何挂载SD卡、写入文件、读取文件、重命名文件、格式化SD卡，最后卸载SD卡。

代码首先包含了必要的头文件，并定义了一些常量，如最大字符大小、SD卡的挂载点和SPI通信的引脚分配。

然后定义了两个辅助函数：s_example_write_file和s_example_read_file。s_example_write_file函数打开一个给定路径的文件，写入数据，然后关闭文件。如果无法打开文件，它会记录一个错误并返回失败状态。s_example_read_file函数打开一个给定路径的文件，从中读取一行，然后关闭文件。如果无法打开文件，它会记录一个错误并返回失败状态。

app_main函数是程序的主入口点。它首先定义了挂载SD卡的配置。然后初始化SPI总线和SD卡插槽。如果初始化失败，它会记录一个错误并返回。

接下来，它试图挂载SD卡。如果挂载失败，它会记录一个错误并返回。如果挂载成功，它会记录一个成功消息并打印SD卡的属性。

程序然后在SD卡上写入一个文件，检查另一个文件是否存在，如果存在则删除它，然后将第一个文件重命名为第二个文件。然后从第二个文件中读取。

程序接着格式化SD卡，并检查第二个文件是否仍然存在。如果存在，它会记录一个消息并返回。如果不存在，它会记录一个成功消息，写入第三个文件，并从第三个文件中读取。

最后，卸载SD卡并禁用SPI外设。

编译：

烧写到ESP32C3后运行，控制台输出：

I (286) app_start: Starting scheduler on CPU0

I (291) main_task: Started on CPU0

I (291) main_task: Calling app_main()

I (291) example: Initializing SD card

I (301) example: Using SPI peripheral

I (301) example: Mounting filesystem

I (311) gpio: GPIO[1]| InputEn: 0| OutputEn: 1| OpenDrain: 0| Pullup: 0| Pulldown: 0| Intr:0

I (321) sdspi_transaction: cmd=52, R1 response: command not supported

I (361) sdspi_transaction: cmd=5, R1 response: command not supported

I (391) example: Filesystem mounted

Name: CS064

Type: SDHC/SDXC

Speed: 20.00 MHz (limit: 20.00 MHz)

Size: 7382MB

CSD: ver=2, sector_size=512, capacity=15118336 read_bl_len=9

SSR: bus_width=1

I (401) example: Opening file /sdcard/hello.txt

I (411) example: File written

I (411) example: Renaming file /sdcard/hello.txt to /sdcard/foo.txt

I (411) example: Reading file /sdcard/foo.txt

I (421) example: Read from file: 'Hello CS064!'

I (421) vfs_fat_sdmmc: Formatting card, allocation unit size=16384

I (2911) example: file doesnt exist, format done

I (2911) example: Opening file /sdcard/nihao.txt

I (2921) example: File written

I (2921) example: Reading file /sdcard/nihao.txt

I (2921) example: Read from file: 'Nihao CS064!'

I (2921) gpio: GPIO[1]| InputEn: 1| OutputEn: 0| OpenDrain: 0| Pullup: 0| Pulldown: 0| Intr:0

I (2931) example: Card unmounted

I (2931) gpio: GPIO[4]| InputEn: 0| OutputEn: 0| OpenDrain: 0| Pullup: 1| Pulldown: 0| Intr:0

I (2941) gpio: GPIO[6]| InputEn: 0| OutputEn: 0| OpenDrain: 0| Pullup: 1| Pulldown: 0| Intr:0

I (2951) gpio: GPIO[5]| InputEn: 0| OutputEn: 0| OpenDrain: 0| Pullup: 1| Pulldown: 0| Intr:0

I (2961) main_task: Returned from app_main()

 

可以看到输出了存储卡信息：

Name: CS064

Type: SDHC/SDXC

Speed: 20.00 MHz (limit: 20.00 MHz)

Size: 7382MB

CSD: ver=2, sector_size=512, capacity=15118336 read_bl_len=9

SSR: bus_width=1

 

后面还输出了读写文件相应的信息。