Code

Add to the main application source file, outside of any functions:

static struct usart_module cdc_instance,lin_instance;

#define LIN_ID_FIELD_VALUE 0x64

#define LIN_DATA_LEN 5
static uint8_t rx_buffer[LIN_DATA_LEN]={0};
const static uint8_t tx_buffer[LIN_DATA_LEN]={0x4a,0x55,0x93,0xe5,0xe6};

Copy-paste the following setup code to your user application:

static void configure_usart_cdc(void)
{

    struct usart_config config_cdc;
    usart_get_config_defaults(&config_cdc);
    config_cdc.baudrate  = 115200;
    config_cdc.mux_setting = EDBG_CDC_SERCOM_MUX_SETTING;
    config_cdc.pinmux_pad0 = EDBG_CDC_SERCOM_PINMUX_PAD0;
    config_cdc.pinmux_pad1 = EDBG_CDC_SERCOM_PINMUX_PAD1;
    config_cdc.pinmux_pad2 = EDBG_CDC_SERCOM_PINMUX_PAD2;
    config_cdc.pinmux_pad3 = EDBG_CDC_SERCOM_PINMUX_PAD3;
    stdio_serial_init(&cdc_instance, EDBG_CDC_MODULE, &config_cdc);
    usart_enable(&cdc_instance);
}

static void lin_read_callback(struct usart_module *const usart_module)
{

    uint8_t i = 0;

    if (CONF_LIN_NODE_TYPE == LIN_MASTER_NODE) {
        for(i = 0; i < LIN_DATA_LEN; i++){
            if(rx_buffer[i] != tx_buffer[i]) {
                printf("Data error\r\n");
                break;
            }
        }
        if(i == LIN_DATA_LEN){
            printf("Slave response: OK\r\n");
        }
    } else if (CONF_LIN_NODE_TYPE == LIN_SLAVE_NODE) {
        if(rx_buffer[0] == LIN_ID_FIELD_VALUE) {
            usart_enable_transceiver(&lin_instance,USART_TRANSCEIVER_TX);
            printf("Receive ID field from mater: OK \r\n");
            usart_write_buffer_job(&lin_instance,
                (uint8_t *)tx_buffer, LIN_DATA_LEN);
        }
    }
}
static void lin_read_error_callback(struct usart_module *const usart_module)
{
      printf("Data Read error\r\n");
}

static void configure_usart_lin(void)
{

    struct port_config pin_conf;
    port_get_config_defaults(&pin_conf);
    pin_conf.direction  = PORT_PIN_DIR_OUTPUT;
    port_pin_set_config(LIN_EN_PIN, &pin_conf);

    /* Enable LIN module*/
    port_pin_set_output_level(LIN_EN_PIN, 1);

    struct usart_config config_lin;
    usart_get_config_defaults(&config_lin);

    /* LIN frame format*/
    config_lin.lin_node = CONF_LIN_NODE_TYPE;
    config_lin.transfer_mode = USART_TRANSFER_ASYNCHRONOUSLY;
    config_lin.sample_rate = USART_SAMPLE_RATE_16X_FRACTIONAL;

    config_lin.baudrate = 115200;
    config_lin.mux_setting = LIN_USART_SERCOM_MUX_SETTING;
    config_lin.pinmux_pad0 = LIN_USART_SERCOM_PINMUX_PAD0;
    config_lin.pinmux_pad1 = LIN_USART_SERCOM_PINMUX_PAD1;
    config_lin.pinmux_pad2 = LIN_USART_SERCOM_PINMUX_PAD2;
    config_lin.pinmux_pad3 = LIN_USART_SERCOM_PINMUX_PAD3;

    /* Disable receiver and transmitter */
    config_lin.receiver_enable  = false;
    config_lin.transmitter_enable = false;

    if (CONF_LIN_NODE_TYPE == LIN_SLAVE_NODE) {
        config_lin.lin_slave_enable = true;
    }

    while (usart_init(&lin_instance,
        LIN_USART_MODULE, &config_lin) != STATUS_OK) {
    }

    usart_enable(&lin_instance);

    usart_register_callback(&lin_instance,
        lin_read_callback, USART_CALLBACK_BUFFER_RECEIVED);
    usart_enable_callback(&lin_instance, USART_CALLBACK_BUFFER_RECEIVED);
      usart_register_callback(&lin_instance,
        lin_read_error_callback, USART_CALLBACK_ERROR);
    usart_enable_callback(&lin_instance, USART_CALLBACK_ERROR);
    system_interrupt_enable_global();
}

Add to user application initialization (typically the start of main()):

system_init();
configure_usart_cdc();