7-1.c

单片机C51的学习程序,内包含大部分的功能学习,适合初学者用.

#include <reg51.h>
#include <stdio.h>
#define  PI  3.14159              
main()
{
int s,r=5;
float s1;
s=PI*r*r;
s1=PI*r*r;
SCON = 0x50; 
TMOD |= 0x20; 
TH1 = 0xf3; 
TR1 = 1;
TI = 1; 
printf ("%f\n",s1);
//printf ("%d\n",s1);
printf ("%d\n",s);
//printf ("%f\n",s);
while(1);
}