printf and scanf in Keil with RealView Compiler

สำหรับการใช้ high-level formatted IO library function ใน Keil เราจำเป็นต้องเตรียม low-level driver ให้เหมาะสมกับ อุปกรณ์ IO ที่เราจะใช้ โดยสำหรับ low-level functions ดังกล่าว Real View library ได้เตรียมไว้แล้วใน file "retarget.c" ซึ่งถูกเก็บในkeil\arm\startup โดย printf และ scanf ก็ถูกเก็บไว้ใน "Retarget.c" ดังนั่น เราต้องนำ "retarget.c" มา add ใน project>>Manage>>Components,Environment,Book.. ด้วย

Main.c

/****************************************************************/

/* Compiler : Keil Realview MDK V4.13a */

/* Target MCU : Philips ARM7-LPC2368 */

/* : X-TAL : 12.00 MHz */

/* : PLL Setup = MSEL(12),NSEL(1) */

/* Create By : Eddy */

/* Last Update : 1/April/2011 */

/* Function : Example Use printf and scanf pass UART0*/

/*****************************************************************/

#include <LPC23xx.H> // LPC2368 MPU Register

#include <stdio.h>

// Pin I/O LED Control Maskbit

#define DIR_RS485 0x00080000 // P1.19(0000 0000 0000 x000 0000 0000 0000 0000)

#define RXD_RS485() IOCLR1 = DIR_RS485 // RS485 Direction = 0 (Receive)

#define TXD_RS485() IOSET1 = DIR_RS485 // RS485 Direction = 1 (Transmit)

char uart0_buf[]; // "sprint" UART[0] Buffer

/* pototype section */

void init_serial0 (void);

void sendchar(int ch); // Put Char To UART-0

int getkey(void); // Get Char From UART-0

void print_uart0(void); // Print String to UART0

void delay(unsigned long int); // Delay Time Function

int main(void)

{

int a,b,c;

init_serial0(); // Initilial UART0 = 9600,N,8,1

printf("\n a = ");

scanf("%d",&a);

printf("\n b = ");

scanf("%d",&b);

// Loop Receive & Echo Test //

while(1) // Loop Continue

{

// UART[0] Print //

c=a*b;

printf("\n c= %d",c);

delay(50000);

}

}

void init_serial0 (void)

{

PINSEL0 &= 0xFFFFFF0F; // Reset P0.2,P0.3 Pin Config

PINSEL0 |= 0x00000010; // Select P0.2 = TxD(UART0)

PINSEL0 |= 0x00000040; // Select P0.3 = RxD(UART0)

U0LCR = 0x83; // 8 bits, no Parity, 1 Stop bit

//****************Baudrate UART = 9600,N,8,1***********************

U0DLL = 0x34; // DLM=DLest[15:8],DLL=DLest[7:0]

U0FDR = 0x21; // Fractional Divider--DivAddVal[3:0]/MulVal[7:4] = 1/2

U0LCR = 0x03; // DLAB = 0

}

/******************************/

/* Write Character To UART[0] */

/******************************/

void sendchar (int ch)

{

if (ch == '\n')

{

while (!(U0LSR & 0x20)); // Wait TXD Buffer Empty

U0THR = 0x0D; // Write CR

}

while (!(U0LSR & 0x20)); // Wait TXD Buffer Empty

U0THR = ch;

}

/******************************/

/* Get character From UART[0] */

/******************************/

int getkey()

{

while (!(U0LSR & 0x01)); // Wait RXD Receive Data Ready

return (U0RBR); // Get Receice Data & Return

}

/***************************/

/* Print String to UART[0] */

/***************************/

void print_uart0(void)

{

char *p; // Pointer Buffer

p = uart0_buf; // UART Buffer

do // Get char & Print Until null

{

sendchar(*p); // Write char to UART

p++; // Next char

}

while(*p != '\0'); // End of ASCII (null)

return;

}

/***********************/

/* Delay Time Function */

/* 1-4294967296 */

/***********************/

void delay(unsigned long int count1)

{

while(count1 > 0) {count1--;} // Loop Decrease Counter

}

Retarget.c

/******************************************************************************/

/* RETARGET.C: 'Retarget' layer for target-dependent low level functions */

/******************************************************************************/

/* This file is part of the uVision/ARM development tools. */

/* Copyright (c) 2005 Keil Software. All rights reserved. */

/* This software may only be used under the terms of a valid, current, */

/* end user licence from KEIL for a compatible version of KEIL software */

/* development tools. Nothing else gives you the right to use this software. */

/******************************************************************************/

#include <stdio.h>

#include <time.h>

#include <rt_misc.h>

#include "LPC23xx.H"

#pragma import(__use_no_semihosting_swi)

extern int sendchar(int ch); /* in Serial.c */

extern int getkey(void); /* in Serial.c */

extern long timeval; /* in Time.c */

struct __FILE { int handle; /* Add whatever you need here */ };

FILE __stdout;

FILE __stdin;

int fputc(int ch, FILE *f) {

return (sendchar(ch));

}

int fgetc(FILE *f) {

return (sendchar(getkey()));

}

int ferror(FILE *f) {

/* Your implementation of ferror */

return EOF;

}

void _ttywrch(int ch) {

sendchar (ch);

}

void _sys_exit(int return_code) {

while (1); /* endless loop */

}