可以用printf函数来打印串口调试信息

只看该作者 · 2016-7-19 19:27

下面这段代码是C8051F34x中串口调试的例程，可以用printf函数来打印串口调试信息。不明白是怎么实现的，貌似通常情况下，printf函数是需要改造一下才能用来打印信息的，请高手帮忙答疑，谢谢了.

#include <c8051f340.h>                // SFR declarations
#include <stdio.h>

#define SYSCLK    12000000          // SYSCLK frequency in Hz
#define BAUDRATE       9600          // Baud rate of UART in bps

void SYSCLK_Init (void);
void UART0_Init (void);
void PORT_Init (void);
void Timer2_Init (int);

void main (void)
{
unsigned char inputcharacter;    // Used to store character from UART
PCA0MD &= ~0x40;                   // WDTE = 0 (clear watchdog timer
                                    // enable)
PORT_Init();                      // Initialize Port I/O
SYSCLK_Init ();                   // Initialize Oscillator
UART0_Init();
while (1)
{
   printf ("\nEnter character: ");
   inputcharacter = getchar ();
   printf ("\nCharacter entered : %c",inputcharacter);
   printf ("\n    Value in Hex: %bx",inputcharacter);
}
}
void PORT_Init (void)
{
P0MDOUT |= 0x10;                   // Enable UTX as push-pull output
XBR0    = 0x01;                   // Enable UART on P0.4(TX) and P0.5(RX)
XBR1    = 0x40;                   // Enable crossbar and weak pull-ups
}

void SYSCLK_Init (void)
{
OSCICN |= 0x03;                   // Configure internal oscillator for
                                    // its maximum frequency
RSTSRC  = 0x04;                   // Enable missing clock detector
}

void UART0_Init (void)
{
SCON0 = 0x10;                      // SCON0: 8-bit variable bit rate
                                    //       level of STOP bit is ignored
                                    //       RX enabled
                                    //       ninth bits are zeros
                                    //       clear RI0 and TI0 bits
if (SYSCLK/BAUDRATE/2/256 < 1) {
   TH1 = -(SYSCLK/BAUDRATE/2);
   CKCON &= ~0x0B;                // T1M = 1; SCA1:0 = xx
   CKCON |=  0x08;
} else if (SYSCLK/BAUDRATE/2/256 < 4) {
   TH1 = -(SYSCLK/BAUDRATE/2/4);
   CKCON &= ~0x0B;                // T1M = 0; SCA1:0 = 01
   CKCON |=  0x01;
} else if (SYSCLK/BAUDRATE/2/256 < 12) {
   TH1 = -(SYSCLK/BAUDRATE/2/12);
   CKCON &= ~0x0B;                // T1M = 0; SCA1:0 = 00
} else {
   TH1 = -(SYSCLK/BAUDRATE/2/48);
   CKCON &= ~0x0B;                // T1M = 0; SCA1:0 = 10
   CKCON |=  0x02;
}
TL1 = TH1;                         // Init Timer1
TMOD &= ~0xf0;                   // TMOD: timer 1 in 8-bit autoreload
TMOD |=  0x20;
TR1 = 1;                         // START Timer1
TI0 = 1;                         // Indicate TX0 ready
}