ex03.c

《单片机c程序设计及应用实列》一书的源代

#include <REG52.H>                /* special function register declarations   */
                                  /* for the intended 8051 derivative         */

#include <stdio.h>                /* prototype declarations for I/O functions */
#include <float.h>	

#ifdef MONITOR51                         /* Debugging with Monitor-51 needs   */
char code reserve [3] _at_ 0x23;         /* space for serial interrupt if     */
#endif                                   /* Stop Exection with Serial Intr.   */
                                         /* is enabled                        */


/*------------------------------------------------
The main C function.  Program execution starts
here after stack initialization.
------------------------------------------------*/
/* 对fahr = 0, 20, ..., 300 打印华氏温度与摄氏温度对照表；
浮点数版本*/
void main (void) {

float fahr, celsius;
int lower, upper, step;
/*------------------------------------------------
Setup the serial port for 1200 baud at 16MHz.
------------------------------------------------*/
#ifndef MONITOR51
    SCON  = 0x50;		        /* SCON: mode 1, 8-bit UART, enable rcvr      */
    TMOD |= 0x20;               /* TMOD: timer 1, mode 2, 8-bit reload        */
    TH1   = 221;                /* TH1:  reload value for 1200 baud @ 16MHz   */
    TR1   = 1;                  /* TR1:  timer 1 run                          */
    TI    = 1;                  /* TI:   set TI to send first char of UART    */
#endif

/*------------------------------------------------
Note that an embedded program never exits (because
there is no operating system to return to).  It
must loop and execute forever.
------------------------------------------------*/
	lower = 0; /* 温度表的下限*/
	upper = 300 ; /* 温度表的上限*/
	step = 20; /* 步长*/
	fahr = lower;
	while (fahr <= upper) {
		celsius = (5.0 / 9.0) * (fahr-32.0);
		printf("%3.0f %6.1f\n", fahr, celsius);
		fahr = fahr + step;
	}
  while (1) {}
}