Code

Add to the main application source file, outside of any functions:
#define AES_EXAMPLE_REFBUF_SIZE 4

/* @{ */
uint32_t ref_plain_text[AES_EXAMPLE_REFBUF_SIZE] = {
    0xe2bec16b,
    0x969f402e,
    0x117e3de9,
    0x2a179373
};

uint32_t ref_cipher_text_ecb[AES_EXAMPLE_REFBUF_SIZE] = {
    0xb47bd73a,
    0x60367a0d,
    0xf3ca9ea8,
    0x97ef6624
};

const uint32_t key128[4] = {
    0x16157e2b,
    0xa6d2ae28,
    0x8815f7ab,
    0x3c4fcf09
};
/* @} */
Add to the main application source file, outside of any functions:
/* Output data array */
static uint32_t output_data[AES_EXAMPLE_REFBUF_SIZE];

/* State indicate */
volatile bool state = false;
/* AES configuration */
struct aes_config g_aes_cfg;
/* AES instance*/
struct aes_module aes_instance;
struct usart_module usart_instance;
Copy-paste the following setup code to your user application:
static void configure_usart(void)
{

    struct usart_config config_usart;
    usart_get_config_defaults(&config_usart);
    config_usart.baudrate    = 38400;
    config_usart.mux_setting = EDBG_CDC_SERCOM_MUX_SETTING;
    config_usart.pinmux_pad0 = EDBG_CDC_SERCOM_PINMUX_PAD0;
    config_usart.pinmux_pad1 = EDBG_CDC_SERCOM_PINMUX_PAD1;
    config_usart.pinmux_pad2 = EDBG_CDC_SERCOM_PINMUX_PAD2;
    config_usart.pinmux_pad3 = EDBG_CDC_SERCOM_PINMUX_PAD3;
    stdio_serial_init(&usart_instance, EDBG_CDC_MODULE, &config_usart);
    usart_enable(&usart_instance);
}

static void ecb_mode_test(void)
{
    printf("\r\n-----------------------------------\r\n");
    printf("- 128bit cryptographic key\r\n");
    printf("- ECB cipher mode\r\n");
    printf("- Auto start mode\r\n");
    printf("- 4 32bit words\r\n");
    printf("-----------------------------------\r\n");


    state = false;

    /* Configure the AES. */
    g_aes_cfg.encrypt_mode = AES_ENCRYPTION;
    g_aes_cfg.key_size = AES_KEY_SIZE_128;
    g_aes_cfg.start_mode = AES_AUTO_START;
    g_aes_cfg.opmode = AES_ECB_MODE;
    g_aes_cfg.cfb_size = AES_CFB_SIZE_128;
    g_aes_cfg.lod = false;
    aes_set_config(&aes_instance,AES, &g_aes_cfg);

    /* Set the cryptographic key. */
    aes_write_key(&aes_instance, key128);

    /* The initialization vector is not used by the ECB cipher mode. */

    aes_set_new_message(&aes_instance);
    /* Write the data to be ciphered to the input data registers. */
    aes_write_input_data(&aes_instance, ref_plain_text);
    aes_clear_new_message(&aes_instance);
    /* Wait for the end of the encryption process. */
    while (!(aes_get_status(&aes_instance) & AES_ENCRYPTION_COMPLETE)) {
    }
    aes_read_output_data(&aes_instance,output_data);

    if ((ref_cipher_text_ecb[0] != output_data[0]) ||
            (ref_cipher_text_ecb[1] != output_data[1]) ||
            (ref_cipher_text_ecb[2] != output_data[2]) ||
            (ref_cipher_text_ecb[3] != output_data[3])) {
        printf("\r\nKO!!!\r\n");
    } else {
        printf("\r\nOK!!!\r\n");
    }
    printf("\r\n-----------------------------------\r\n");
    printf("- 128bit cryptographic key\r\n");
    printf("- ECB decipher mode\r\n");
    printf("- Auto start mode\r\n");
    printf("- 4 32bit words\r\n");
    printf("-----------------------------------\r\n");


    state = false;

    /* Configure the AES. */
    g_aes_cfg.encrypt_mode = AES_DECRYPTION;
    g_aes_cfg.key_size = AES_KEY_SIZE_128;
    g_aes_cfg.start_mode = AES_AUTO_START;
    g_aes_cfg.opmode = AES_ECB_MODE;
    g_aes_cfg.cfb_size = AES_CFB_SIZE_128;
    g_aes_cfg.lod = false;
    aes_set_config(&aes_instance,AES, &g_aes_cfg);

    /* Set the cryptographic key. */
    aes_write_key(&aes_instance, key128);

    /* The initialization vector is not used by the ECB cipher mode. */

    /* Write the data to be deciphered to the input data registers. */
    aes_write_input_data(&aes_instance, ref_cipher_text_ecb);

    /* Wait for the end of the decryption process. */
    while (!(aes_get_status(&aes_instance) & AES_ENCRYPTION_COMPLETE)) {
    }
    aes_read_output_data(&aes_instance,output_data);

    /* check the result. */
    if ((ref_plain_text[0] != output_data[0]) ||
            (ref_plain_text[1] != output_data[1]) ||
            (ref_plain_text[2] != output_data[2]) ||
            (ref_plain_text[3] != output_data[3])) {
        printf("\r\nKO!!!\r\n");
    } else {
        printf("\r\nOK!!!\r\n");
    }

}
Add to user application initialization (typically the start of main()):
/* Initialize the system and console*/
system_init();
configure_usart();

aes_get_config_defaults(&g_aes_cfg);

aes_init(&aes_instance,AES, &g_aes_cfg);
aes_enable(&aes_instance);