下面这个程序有几点疑问请高手解答：
1：这是中断方式？它和查询方式的区别，我总是分不开
2：say_cl_fy有什么作用
3：主函数的TI为什么先置1，a为什么又给赋了个字符，里面的d什么作用？？？
新手迷茫中，，，，，，，，
#include <reg52.h>
#define uchar unsigned char
#define uint unsigned int
uchar a;
sbit d = P3^7;
//--------------------------------------
say_CR_LF()
{
SBUF = 13; while (TI == 0); TI = 0;
SBUF = 10; while (TI == 0); TI = 0;
}
//--------------------------------------
say_yeah()
{
SBUF = a; while (TI == 0); TI = 0;
SBUF = ','; while (TI == 0); TI = 0;
SBUF = ' '; while (TI == 0); TI = 0;
SBUF = 'y'; while (TI == 0); TI = 0;
SBUF = 'e'; while (TI == 0); TI = 0;
SBUF = 'a'; while (TI == 0); TI = 0;
SBUF = 'h'; while (TI == 0); TI = 0;
SBUF = '!'; while (TI == 0); TI = 0;
say_CR_LF();
}
//--------------------------------------
say_hello()
{
SBUF = 'H'; while (TI == 0); TI = 0;
SBUF = 'e'; while (TI == 0); TI = 0;
SBUF = 'l'; while (TI == 0); TI = 0;
SBUF = 'l'; while (TI == 0); TI = 0;
SBUF = 'o'; while (TI == 0); TI = 0;
SBUF = '!'; while (TI == 0); TI = 0;
say_CR_LF();
}
//--------------------------------------
void init()
{
SCON = 0x50; //设置串口通信方式1, 允许接收
PCON &= 0x7F;
TMOD = 0x20; //设置T1定时方式2
TH1 = 0xfd; // 9600bps @ 11.0592MHz
TL1 = 0xfd;
TR1 = 1; //启动T1
ES = 1; //开串口中断.
EA = 1; //开总中断.
say_hello();
}
//--------------------------------------
void delay(uint z)
{
uint x, y;
for(x = z; x > 0; x--) for(y = 110; y > 0; y--);
}
//--------------------------------------
void main()
{
init();
TI = 1;
a = '4';
while(1) {
if(a == '1') {
d = 0; delay(400);
d = 1; delay(400);
}
else if(a == '2') {
d = 0; delay(200);
d = 1; delay(200);
}
else if(a == '3') {
d = 0; delay(100);
d = 1; delay(100);
}
else if(a == '4') {
d = 1;
} } }
//--------------------------------------
void ser() interrupt 4
{
if (TI == 1) TI = 0;
if (RI == 1) {
RI = 0;
P0 = SBUF;
a = SBUF; //中间变量.
say_yeah();
} }
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