Question

关于51 C编程中使用stdio.h开发串口，使用printf的问题

我只在开始调用了include<stdio.h>然后在主函数中直接使用printf("temp")，编译没有错误，但是下载到单片机里使用时在串口调试助手里没收到数据，这是怎么回事，该怎么正确使用stdio.h呢？

Answer 1

在单片机中用printf通过串口输出需要对串口进行相应配置，你可以在KEIL51的例程中看到一个HELLO的程序。

/*------------------------------------------------------------------------------
HELLO.C

Copyright 1995-2005 Keil Software, Inc.
------------------------------------------------------------------------------*/

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

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

#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.
------------------------------------------------*/
void main (void) {

/*------------------------------------------------
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.
------------------------------------------------*/
while (1) {
P1 ^= 0x01; /* Toggle P1.0 each time we print */
printf ("Hello World\n"); /* Print "Hello World" */
}
}