http_server: The example adds a new function about file saving to SDcard

examples/protocols/http_server/file_serving/README.md

@@ -2,6 +2,8 @@
 
 (See the README.md file in the upper level 'examples' directory for more information about examples.)
 
+If the SD card option is enabled, you can access files in the SD card by the path `/sdcard` 
+
 HTTP file server example demonstrates file serving with both upload and download capability, using the `esp_http_server` component of ESP-IDF. The following URIs are provided by the server:
 
 | URI                  | Method  | Description                                                                               |
@@ -38,6 +40,12 @@ File server implementation can be found under `main/file_server.c` which uses SP
         2. download the uploaded copy back : `curl 192.168.43.130:80/path/on/device/myfile_copy.html > myfile_copy.html`
         3. compare the copy with the original using `cmp myfile.html myfile_copy.html`
 
+* To write to SD card, you need to:
+    1. Select the `Mount the SD card to the filesystem` in the configuration menu (by calling `idf.py menuconfig` and select the `EXAMPLE_MOUNT_SD_CARD` option.
+    2. If you need to format the card while the card fails to be mounted, enable the config option `The card will be formatted if mount has failed` (`EXAMPLE_FORMAT_SDCARD_IF_MOUNT_FAILED`). Be careful, all the data in the card will disappear.
+
+    Note: You will have to access the SD card by SPI bus with sdspi driver, if you are using ESP32S2.
+
 ## Note
 
 Browsers often send large header fields when an HTML form is submit. Therefore, for the purpose of this example, `HTTPD_MAX_REQ_HDR_LEN` has been increased to 1024 in `sdkconfig.defaults`. User can adjust this value as per their requirement, keeping in mind the memory constraint of the hardware in use.

examples/protocols/http_server/file_serving/main/Kconfig.projbuild

@@ -0,0 +1,24 @@
+menu "Http_File_Serving Example menu"
+
+    config EXAMPLE_MOUNT_SD_CARD
+        bool "Mount the SD card to the filesystem"
+        default n
+        help
+            If this config item is set, the file you upload to server can be chosen to save in the SDcard.
+
+    config EXAMPLE_FORMAT_IF_MOUNT_SDCARD_FAILED
+        bool "The card will be formatted if mount has failed."
+        default n
+        depends on EXAMPLE_MOUNT_SD_CARD
+        help
+            If this config item is set, the card will be formatted if mount has failed.
+
+    config EXAMPLE_USE_SDMMC_HOST
+        bool "Use SDMMC host"
+        default y
+        depends on EXAMPLE_MOUNT_SD_CARD && IDF_TARGET_ESP32
+        help
+            If this config item is set, SDMMC is used to mount the SDcard.
+            Otherwise, will use SPI host to access and mount the SDcard.
+
+endmenu

examples/protocols/http_server/file_serving/main/main.c

@@ -7,22 +7,67 @@
    CONDITIONS OF ANY KIND, either express or implied.
 */
 
+#include <stdio.h>
+#include <string.h>
+#include <sys/unistd.h>
+#include <sys/stat.h>
 #include <sys/param.h>
-
 #include "esp_wifi.h"
 #include "esp_event.h"
 #include "esp_log.h"
 #include "esp_system.h"
 #include "esp_spiffs.h"
-#include "nvs_flash.h"
 #include "esp_netif.h"
+#include "esp_err.h"
+#include "esp_vfs_fat.h"
+#include "nvs_flash.h"
 #include "protocol_examples_common.h"
+#include "sdkconfig.h"
+#include "driver/sdspi_host.h"
+#include "driver/spi_common.h"
+#include "sdmmc_cmd.h"
+#include "soc/soc_caps.h"
+#if SOC_SDMMC_HOST_SUPPORTED
+#include "driver/sdmmc_host.h"
+#endif
 
 /* This example demonstrates how to create file server
  * using esp_http_server. This file has only startup code.
  * Look in file_server.c for the implementation */
 
+#define MOUNT_POINT "/sdcard"
 static const char *TAG="example";
+/* ESP32-S2 doesn't have an SD Host peripheral, always use SPI,
+ * ESP32 can choose SPI or SDMMC Host, SPI is used by default: */
+
+#ifndef CONFIG_EXAMPLE_USE_SDMMC_HOST
+#define USE_SPI_MODE
+#endif
+// on ESP32-S2, DMA channel must be the same as host id
+#ifdef CONFIG_IDF_TARGET_ESP32S2
+#define SPI_DMA_CHAN    host.slot
+#endif //CONFIG_IDF_TARGET_ESP32S2
+// DMA channel to be used by the SPI peripheral
+#ifdef CONFIG_IDF_TARGET_ESP32
+#define SPI_DMA_CHAN    1
+#endif //SPI_DMA_CHAN
+
+// When testing SD and SPI modes, keep in mind that once the card has been
+// initialized in SPI mode, it can not be reinitialized in SD mode without
+// toggling power to the card.
+#ifdef CONFIG_EXAMPLE_MOUNT_SD_CARD
+static sdmmc_card_t* mount_card = NULL;
+static char * mount_base_path = MOUNT_POINT;
+#endif
+#ifdef USE_SPI_MODE
+// Pin mapping when using SPI mode.
+// With this mapping, SD card can be used both in SPI and 1-line SD mode.
+// Note that a pull-up on CS line is required in SD mode.
+#define PIN_NUM_MISO 2
+#define PIN_NUM_MOSI 15
+#define PIN_NUM_CLK  14
+#define PIN_NUM_CS   13
+#endif //USE_SPI_MODE
 
 /* Function to initialize SPIFFS */
 static esp_err_t init_spiffs(void)
@@ -63,9 +108,110 @@ static esp_err_t init_spiffs(void)
  * Implementation of this function is to be found in
  * file_server.c */
 esp_err_t start_file_server(const char *base_path);
+#ifdef CONFIG_EXAMPLE_MOUNT_SD_CARD
+void sdcard_mount(void)
+{
+    /*sd_card part code*/
+    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");
+
+#ifndef USE_SPI_MODE
+    ESP_LOGI(TAG, "Using SDMMC peripheral");
+    sdmmc_host_t host = SDMMC_HOST_DEFAULT();
+
+    // 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.
+    sdmmc_slot_config_t slot_config = SDMMC_SLOT_CONFIG_DEFAULT();
+
+    // To use 1-line SD mode, uncomment the following line:
+    // slot_config.width = 1;
+
+    // GPIOs 15, 2, 4, 12, 13 should have external 10k pull-ups.
+    // Internal pull-ups are not sufficient. However, enabling internal pull-ups
+    // does make a difference some boards, so we do that here.
+    gpio_set_pull_mode(15, GPIO_PULLUP_ONLY);   // CMD, needed in 4- and 1- line modes
+    gpio_set_pull_mode(2, GPIO_PULLUP_ONLY);    // D0, needed in 4- and 1-line modes
+    gpio_set_pull_mode(4, GPIO_PULLUP_ONLY);    // D1, needed in 4-line mode only
+    gpio_set_pull_mode(12, GPIO_PULLUP_ONLY);   // D2, needed in 4-line mode only
+    gpio_set_pull_mode(13, GPIO_PULLUP_ONLY);   // D3, needed in 4- and 1-line modes
+
+    esp_err_t ret = esp_vfs_fat_sdmmc_mount(mount_point, &host, &slot_config, &mount_config, &card);
+#else
+    ESP_LOGI(TAG, "Using SPI peripheral");
+
+    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,
+    };
+    
+    esp_err_t ret = spi_bus_initialize(host.slot, &bus_cfg, SPI_DMA_CHAN);
+    if (ret != ESP_OK) {
+        ESP_LOGE(TAG, "Failed to initialize bus.");
+        ESP_ERROR_CHECK(ret);
+    }
+
+    // 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;
+    ret = esp_vfs_fat_sdspi_mount(mount_point, &host, &slot_config, &mount_config, &card);
+    mount_card = card;
+#endif //USE_SPI_MODE
+    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 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));
+        }
+        ESP_ERROR_CHECK(ret);        
+    }
+    sdmmc_card_print_info(stdout, card);
+
+}
+#endif
+
+static esp_err_t unmount_card(const char* base_path, sdmmc_card_t* card)
+{
+#ifdef USE_SPI_MODE
+    esp_err_t err = esp_vfs_fat_sdcard_unmount(base_path, card);
+#else
+    esp_err_t err = esp_vfs_fat_sdmmc_unmount();
+#endif
+    ESP_ERROR_CHECK(err);
+#ifdef USE_SPI_MODE
+    sdmmc_host_t host = SDSPI_HOST_DEFAULT();
+    err = spi_bus_free(host.slot);
+#endif
+    ESP_ERROR_CHECK(err);
+
+    return err;
+}
 
 void app_main(void)
 {
+    /*Mount the SDcard first if needed.*/
+#ifdef CONFIG_EXAMPLE_MOUNT_SD_CARD
+    sdcard_mount();
+#endif
+    
     ESP_ERROR_CHECK(nvs_flash_init());
     ESP_ERROR_CHECK(esp_netif_init());
     ESP_ERROR_CHECK(esp_event_loop_create_default());
@@ -81,4 +227,9 @@ void app_main(void)
 
     /* Start the file server */
     ESP_ERROR_CHECK(start_file_server("/spiffs"));
+
+#ifdef CONFIG_EXAMPLE_MOUNT_SD_CARD
+    //deinitialize the bus after all devices are removed
+    ESP_ERROR_CHECK(unmount_card(mount_base_path, mount_card));
+#endif
 }

examples/protocols/http_server/file_serving/sdkconfig.ci

@@ -0,0 +1,3 @@
+CONFIG_EXAMPLE_MOUNT_SD_CARD=y
+CONFIG_EXAMPLE_FORMAT_IF_MOUNT_SDCARD_FAILED=y
+CONFIG_EXAMPLE_USE_SDMMC_HOST=y