SAML21走起2：查询方式UART

printf("Usart data is %d",usart_instance->hw.usart->DATA.reg); 但是首先提示我一个错误就是 usart_instance have “struct_module”

其次就是这个printf函数也不能正常使用

/**

 * \file

 *

 * \brief Empty user application template

 *

 */



/**

 * \mainpage User Application template doxygen documentation

 *

 * \par Empty user application template

 *

 * Bare minimum empty user application template

 *

 * \par Content

 *

 * -# Include the ASF header files (through asf.h)

 * -# Minimal main function that starts with a call to system_init()

 * -# "Insert application code here" comment

 *

 */



/*

 * Include header files for all drivers that have been imported from

 * Atmel Software Framework (ASF).

 */

/*

 * Support and FAQ: visit <a href="http://www.atmel.com/design-support/">Atmel Support</a>

 */





#include <asf.h>

#include <stdio.h>



//#include <NskBMD.h>

#define LED 91 //定义LED所使用的IO口为 PC27

#define KEY 65 //定义KEY所使用的IO口为 PC01

void port_init(void);

void configure_usart(void);

//! [setup_config]

struct usart_module usart_instance;

//! [setup_config]



/***********************************************/

//串口初始化

/**********************************************/



void configure_usart(void)

{

          

        //! [setup_config]

        struct usart_config config_usart;

        //! [setup_config]

        

        //! [setup_config_defaults]

        usart_get_config_defaults(&config_usart);

        //! [setup_config_defaults]



        //! [setup_change_config]

        //USART  PORT  PA12 PA13.

        config_usart.baudrate    = 9600;

        config_usart.mux_setting = USART_RX_3_TX_2_XCK_3;

        config_usart.pinmux_pad0 = PINMUX_UNUSED;//PINMUX_PA12D_SERCOM3_PAD0;

        config_usart.pinmux_pad1 = PINMUX_UNUSED;//PINMUX_PA13D_SERCOM3_PAD1;

        config_usart.pinmux_pad2 = PINMUX_PC24D_SERCOM4_PAD2;//PINMUX_UNUSED;

        config_usart.pinmux_pad3 = PINMUX_PC25D_SERCOM4_PAD3;//PINMUX_UNUSED;

        //! [setup_change_config]



        //! [setup_set_config]

        while (usart_init(&usart_instance,

        SERCOM4, &config_usart) != STATUS_OK) {

                

        }

        //! [setup_set_config]



        //! [setup_enable]

        usart_enable(&usart_instance);

        //! [setup_enable]

}









/******************************************************/

// # IO口初始化

/******************************************************/

void port_init(void)

{

        struct port_config config_port_pin;

        port_get_config_defaults(&config_port_pin);

        

        config_port_pin.direction = PORT_PIN_DIR_OUTPUT; //配置IO口为输出模式;

        port_pin_set_config(LED,&config_port_pin); //初始化LED对应的IO口;

        

        config_port_pin.direction = PORT_PIN_DIR_INPUT; //配置IO口为输入模式;

        config_port_pin.input_pull = PORT_PIN_PULL_UP; //配置IO口为PULL 上拉;

        port_pin_set_config(KEY,&config_port_pin);        

}



int main(void)

{

        system_init();

    port_init(); //端口初始化;

        

        //! [setup_init]

        configure_usart();

        //! [setup_init]

        

        //! [main_send_string]

        uint8_t string[] = "Hello World!\r\n";

        usart_write_buffer_wait(&usart_instance, string, sizeof(string));

        //printf("data is %ld",(usart_instance->hw->USART.DATA->reg));   //添加这块代码就会报警出错。

        //! [main_send_string]

    uint16_t temp;

        //! [main_loop]

        while (1) {

                if (usart_read_wait(&usart_instance, &temp) == STATUS_OK) {

                        //! [main_read]

                        //! [main_write]

                        while (usart_write_wait(&usart_instance, temp) != STATUS_OK) {

                        }

                        //! [main_write]

                }

        }

        //! [main]

}