int main(void)
{	
	delay_init();	      //初始化延时
	uart_init(9600); 	  //初始化串口1,9600,8n1
	USART2_Init(9600);	//初始化串口2,9600,8n1
	usart3_init(9600);  //初始化串口3,9600,8n1
	NVIC_Configuration(); 	 //设置NVIC中断分组2:2位抢占优先级,2位响应优先级 
	
	while(1) 
	{
		printf("send test--USART1");
		delay_ms(1000);
		u2_printf("send test--USART2");
		delay_ms(1000);
		u3_printf("send test--USART3");
		delay_ms(1000);
	}	  
	
}
                                    
                                    
                                        
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