xs128 sci 解析

//功能说明：MC9S12XS128--SCI例程

//使用说明：实现PC→MCU→PC通信，用户可以根据需要修改程序，实现PC→MCU或者//MCU→PC通信

//----------------------------------------------------------------------------------------------------------------// #include /*commondefinesandmacros*/

#include "derivative.h" /*derivative-specificdefinitions*/

//unsigned char txt[]={"Hello World!"};

void delay (unsigned int time)

{

unsigned int i,j,k;

for(i=0;i<125;i++)

for(j=0;j<125;j++)

for(k=time;k>0;k--);

}//延时*/

//-----------------------初始化SCI0----------------------------//

void SciInit()

{

SCI0BD=52; //9600bps Baud Rate=Bus Clock/(16*SCIBD)

//SCI0BDL=(byte)(8000000/9600/16)=52;//设置总线为8M时SCI波特率为9600Hz SCI0CR1=0; //正常8位模式，无奇偶校验

SCI0CR2=0X2C; //发送允许接受中断允许

}

//----------------------读SCI数据-----------------------------//

unsigned char SciRead()

{

if(SCI0SR1_RDRF==1) //表明数据从位移寄存器传输到SCI

//数据寄存器

{

SCI0SR1_RDRF=1; //读取数据寄存器会将RDRF清除重新置位

return SCI0DRL; //返回数据寄存器的数据

}

}

//-----------------写SCI数据---------------------------------//

void SciWrite(unsigned char sendchar)

{

while(!(SCI0SR1&0x80));//TDRE为0时即不忙才往下执行

SCI0DRH=0;

SCI0DRL=sendchar;

}

//------------------------main----------------------------------//

void main(void)

{

SciInit();

EnableInterrupts;

for(;;)

{

}/*waitforever*/

/*please make sure that you never leave this function*/

}

//---------------------------接收中断函数-----------------------// #pragma CODE_SEG NON_BANKED

void interrupt 20 SCI0_re(void)

{

unsigned char ch;

ch=SciRead();

SciWrite(ch);

}