diff --git a/README.md b/README.md
index 88a347b..969bb6d 100644
--- a/README.md
+++ b/README.md
@@ -2,13 +2,27 @@ ESP32 Soundboard
 ================
 Soundboard (computer program), a web application or computer program with buttons that play short, often humorous sound clips.
 
+
 ## Hardware
 * [ESP32] µC
 * [MAX98357A] PCM Input Class D Audio Power Amplifiers
 * [SD card]
 
+
 ## Wiring
-tbd
+
+### SD card
+ESP32 pin     | SD card pin | Notes
+--------------|-------------|------------
+GPIO14 (MTMS) | CLK         | 10k pullup
+GPIO15 (MTDO) | CMD         | 10k pullup
+GPIO2         | D0          | 10k pullup, pull low to go into download mode
+GPIO4         | D1          | 10k pullup; not used in 1-line mode
+GPIO12 (MTDI) | D2          | otherwise 10k pullup (see note below!); not used in 1-line mode
+GPIO13 (MTCK) | D3          | 10k pullup needed at card side, even in 1-line mode
+N/C           | CD          |
+N/C           | WP          |
+
 
 ## Build
 ```bash
@@ -26,6 +40,7 @@ platformio run -t upload && platformio device monitor -b 115200
 * internal DAC?
 * Add-ons?
 
+
 ## References
 
 [ESP32 overview]: http://esp32.net
diff --git a/src/main.cpp b/src/main.cpp
index b6b62ea..5770874 100644
--- a/src/main.cpp
+++ b/src/main.cpp
@@ -8,11 +8,13 @@
 #include "Arduino.h"
 
 #include "keyboard.h"
+#include "sdcard.h"
 
 #define VERSION "0.0"
 #define LED_PIN 21
 
 Keyboard keyboard;
+SDCard sdcard;
 
 void setup()
 {
@@ -26,6 +28,7 @@ void setup()
   Serial.println("-------------------------------------");
 
   keyboard.init();
+  sdcard.mount();
 }
 
 void loop()
diff --git a/src/sdcard.cpp b/src/sdcard.cpp
new file mode 100644
index 0000000..e33f285
--- /dev/null
+++ b/src/sdcard.cpp
@@ -0,0 +1,90 @@
+/*
+ * SD card
+ *
+ * https://github.com/espressif/esp-idf/tree/master/examples/storage/sd_card
+ */
+
+#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/sdmmc_defs.h"
+#include "sdmmc_cmd.h"
+
+#include "sdcard.h"
+
+using namespace std;
+
+static const char* TAG = "SDCard";
+
+SDCard::SDCard() {
+}
+
+void SDCard::mount() {
+    ESP_LOGI(TAG, "Initializing SD card");
+
+    sdmmc_host_t host = SDMMC_HOST_DEFAULT();
+
+    // To use 1-line SD mode, uncomment the following line:
+    // host.flags = SDMMC_HOST_FLAG_1BIT;
+
+    // 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();
+
+    // 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
+    };
+
+    // 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 (%d). Make sure SD card lines have pull-up resistors in place.", ret);
+        }
+        return;
+    }
+
+    // Card has been initialized, print its properties
+    sdmmc_card_print_info(stdout, card);
+}
+
+void SDCard::umount() {
+    // All done, unmount partition and disable SDMMC host peripheral
+    esp_vfs_fat_sdmmc_unmount();
+    ESP_LOGI(TAG, "Card unmounted");
+}
+
+int SDCard::readFile(const char *path){
+    ESP_LOGI(TAG, "Reading file");
+    FILE* f = fopen("/sdcard/foo.txt", "r");
+    if (f == NULL) {
+        ESP_LOGE(TAG, "Failed to open file for reading");
+        return -1;
+    }
+    char line[64];
+    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 0;
+}
diff --git a/src/sdcard.h b/src/sdcard.h
new file mode 100644
index 0000000..adc42b3
--- /dev/null
+++ b/src/sdcard.h
@@ -0,0 +1,13 @@
+#ifndef _SDCARD_H
+#define _SDCARD_H
+
+class SDCard {
+  public:
+    SDCard();
+    void mount();
+    void umount();
+    int readFile(const char *path);
+  private:
+};
+
+#endif /* _SDCARD_H */