#include "stdio.h"　　//必不可缺少

char putchar (char c)

{

    /* Write a character to the USART */

    USART_SendData8(USART1, c);

    /* Loop until the end of transmission */

    while (USART_GetFlagStatus(USART1, USART_FLAG_TC) == RESET);

    return (c);

}

typedef struct

{

    uint16_t time;

    uint8_t cRssi;

}SysParam;

SysParam Sys;//定义了一个结构体数据

printf("hello world!");

printf("rssi %d\r\n",Sys.cRssi);

printf("rssi %d\r\n",Sys.time);

printf("rssi %d\r\n",（uint16_t）Sys.cRssi);