最近收到了一片國產工業級SD NAND，可以替代SD卡，容量大，貼片封裝，非常適合做飛控"黑匣子"。

不用寫驅動程序自帶壞塊管理的NAND Flash（貼片式TF卡），尺寸小巧，簡單易用，兼容性強，穩定可靠，固件可定制，LGA-8封裝，標準SDIO接口，兼容SPI/SD接口，兼容各大MCU平臺，可替代普通TF卡/SD卡，尺寸6x8mm毫米，內置SLC晶圓擦寫壽命10萬次，通過1萬次隨機掉電測試耐高低溫，支持工業級溫度-40°~+85°，機貼手貼都非常方便，速度級別Class10（讀取速度23.5MB/S寫入速度12.3MB/S）標準的SD 2.0協議使得用戶可以直接移植標準驅動代碼，省去了驅動代碼編程環節。支持TF卡啟動的SOC都可以用SD NAND，廠商提供了STM32參考例程及原廠技術支持，主流容量：128MB/512MB/2GB/4GB/8GB，比TF卡穩定，比eMMC便宜。

飛控板上ESP32C3的SDIO接口暫時用不了，只能先用SPI接口驅動。

評估板做了個micro SD卡的接口，方便直接插到帶卡槽的開發板上進行調試。

ESP32C3的SPI接口是硬件SPI，支持DMA，速度應該還可以，但是我用杜邦線連接的，肯定會影響信號質量，估計時鐘很難跑到50MHz了。

接線：

編寫測試程序：

/* SD card and FAT filesystem example.

This example uses SPI peripheral to communicate with SD card.

This example code is in the Public Domain (or CC0 licensed, at your option.)

Unless required by applicable law or agreed to in writing, this

software is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR

CONDITIONS OF ANY KIND, either express or implied.

*/

#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);

}

這段代碼是使用SPI（串行外設接口）與SD卡進行通信。它展示了如何掛載SD卡、寫入文件、讀取文件、重命名文件、格式化SD卡，最后卸載SD卡。

代碼首先包含了必要的頭文件，并定義了一些常量，如最大字符大小、SD卡的掛載點和SPI通信的引腳分配。

然后定義了兩個輔助函數：s_example_write_file和s_example_read_file。s_example_write_file函數打開一個給定路徑的文件，寫入數據，然后關閉文件。如果無法打開文件，它會記錄一個錯誤并返回失敗狀態。s_example_read_file函數打開一個給定路徑的文件，從中讀取一行，然后關閉文件。如果無法打開文件，它會記錄一個錯誤并返回失敗狀態。

app_main函數是程序的主入口點。它首先定義了掛載SD卡的配置。然后初始化SPI總線和SD卡插槽。如果初始化失敗，它會記錄一個錯誤并返回。

接下來，它試圖掛載SD卡。如果掛載失敗，它會記錄一個錯誤并返回。如果掛載成功，它會記錄一個成功消息并打印SD卡的屬性。

程序然后在SD卡上寫入一個文件，檢查另一個文件是否存在，如果存在則刪除它，然后將第一個文件重命名為第二個文件。然后從第二個文件中讀取。

程序接著格式化SD卡，并檢查第二個文件是否仍然存在。如果存在，它會記錄一個消息并返回。如果不存在，它會記錄一個成功消息，寫入第三個文件，并從第三個文件中讀取。

最后，卸載SD卡并禁用SPI外設。

編譯：

燒寫到ESP32C3后運行，控制臺輸出：

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()

可以看到輸出了存儲卡信息：

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

后面還輸出了讀寫文件相應的信息。