Proof of concept DONE: txt loaded from SD, printed on display.

main/main.cpp

@@ -16,9 +16,12 @@
 #include "spi_master_lobo.h"
 #include "img_hacking.c"
 #include "EPD.h"
+#include "storage.h"
 
 #define APP_VERSION "0.1"
 
+static const char *TAG = "main";
+
 static struct tm* tm_info;
 static char tmp_buff[128];
 static time_t time_now, time_last = 0;
@@ -88,10 +91,15 @@ void fs_init()
     vfs_spiffs_register();
     if (spiffs_is_mounted) {
         ESP_LOGI(tag, "File system mounted.");
-    }
-    else {
+    } else {
         ESP_LOGE(tag, "Error mounting file system.");
     }
+
+    if (storage_init() == 0) {
+        ESP_LOGI(tag, "SD card mounted.");
+    } else {
+        ESP_LOGE(tag, "Error mounting SD card.");
+    }
 }
 
 extern "C" void app_main()
@@ -103,33 +111,49 @@ extern "C" void app_main()
 
     printf("\n   LilyBook v%s\n\n", APP_VERSION);
 
+    fs_init();
+
 	display_connect();
 
 	EPD_DisplayClearFull();
     
-    fs_init();
-    
 	printf("==== START ====\r\n\n");
 
+    FILE* f = fopen("/sdcard/book.txt", "r");
+
 	_gs = 1;
 	uint32_t tstart;
 	int pass = 0;
-    int f = DEFAULT_FONT;
-    while (1) {
-    	EPD_DisplayClearPart();
+    int font = DEFAULT_FONT;
 
+    while (1) {
 		EPD_fillScreen(_bg);
 		_fg = 15;
 		_bg = 0;
 
-        EPD_setFont(f++ % USER_FONT, NULL);
-        EPD_print("Welcome to LilyBook", 10, 10);
+        EPD_setFont(font++ % USER_FONT, NULL);
+
+        char text[128];
+        
+        if (f == NULL) {
+            ESP_LOGE(TAG, "Failed to open file for reading");
+            sprintf(text, "Could not open SD card.");
+            f = fopen("/sdcard/book.txt", "r");
+        } else {
+            if (fgets(text, sizeof(text), f) == NULL) {
+                ESP_LOGI(TAG, "End of file, closing.");
+                fclose(f);
+                f = NULL;
+            } else {
+                ESP_LOGI(TAG, "Read content: %s", text);
+            }
+        }
+
+        text_wrap = 1;
+        EPD_print(text, 10, 10);
         EPD_UpdateScreen();
 
         EPD_wait(5000);
-
-    	EPD_PowerOff();
-		EPD_wait(8000);
     }
 
 }

main/storage.cpp

@@ -0,0 +1,102 @@
+
+#include <stdio.h>
+#include <string.h>
+#include <sys/unistd.h>
+#include <sys/stat.h>
+#include "esp_err.h"
+#include "esp_log.h"
+#include "esp_vfs_fat.h"
+#include "driver/sdmmc_host.h"
+#include "driver/sdspi_host.h"
+#include "sdmmc_cmd.h"
+#include "storage.h"
+
+static const char *TAG = "storage";
+
+// This example can use SDMMC and SPI peripherals to communicate with SD card.
+// By default, SDMMC peripheral is used.
+// To enable SPI mode, uncomment the following line:
+
+//#define USE_SPI_MODE
+
+// 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 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 ((gpio_num_t)2)
+#define PIN_NUM_MOSI ((gpio_num_t)15)
+#define PIN_NUM_CLK  ((gpio_num_t)14)
+#define PIN_NUM_CS   ((gpio_num_t)13)
+#endif //USE_SPI_MODE
+
+int storage_init()
+{
+#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((gpio_num_t)15, GPIO_PULLUP_ONLY);   // CMD, needed in 4- and 1- line modes
+    gpio_set_pull_mode((gpio_num_t)2, GPIO_PULLUP_ONLY);    // D0, needed in 4- and 1-line modes
+    //gpio_set_pull_mode((gpio_num_t)4, GPIO_PULLUP_ONLY);    // D1, needed in 4-line mode only
+    //gpio_set_pull_mode((gpio_num_t)12, GPIO_PULLUP_ONLY);   // D2, needed in 4-line mode only
+    gpio_set_pull_mode((gpio_num_t)13, GPIO_PULLUP_ONLY);   // D3, needed in 4- and 1-line modes
+
+#else
+    ESP_LOGI(TAG, "Using SPI peripheral");
+
+    sdmmc_host_t host = SDSPI_HOST_DEFAULT();
+    sdspi_slot_config_t slot_config = SDSPI_SLOT_CONFIG_DEFAULT();
+    slot_config.gpio_miso = PIN_NUM_MISO;
+    slot_config.gpio_mosi = PIN_NUM_MOSI;
+    slot_config.gpio_sck  = PIN_NUM_CLK;
+    slot_config.gpio_cs   = PIN_NUM_CS;
+    // 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.
+#endif //USE_SPI_MODE
+
+    // 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 = {
+        .format_if_mount_failed = false,
+        .max_files = 5,
+        .allocation_unit_size = 16 * 1024
+    };
+
+    // Use settings defined above to initialize SD card and mount FAT filesystem.
+    // Note: esp_vfs_fat_sdmmc_mount is an all-in-one convenience function.
+    // Please check its source code and implement error recovery when developing
+    // production applications.
+    sdmmc_card_t* card;
+    esp_err_t ret = esp_vfs_fat_sdmmc_mount("/sdcard", &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 format_if_mount_failed = true.");
+        } 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 -1;
+    }
+
+    // Card has been initialized, print its properties
+    sdmmc_card_print_info(stdout, card);
+
+    return 0;
+}

main/storage.h

@@ -0,0 +1,2 @@
+
+int storage_init();