UARTサンプル

#include <stdio.h>
#include <htc.h>
#include "usart.h"

 __CONFIG(MCLRE_OFF & PWRTE_ON & WDTE_OFF & FOSC_INTOSCIO & LVP_OFF);

void main(void){
	unsigned char input;

	INTCON=0;	// purpose of disabling the interrupts.

	init_comms();	// set up the USART - settings defined in usart.h

	// Output a message to prompt the user for a keypress	
	printf("\rPress a key and I will echo it back:\n");
	while(1){
		input = getch();	// read a response from the user
		printf("\rI detected [%c]",input);	// echo it back
	}
}

usart.h

#ifndef _SERIAL_H_
#define _SERIAL_H_

#define BAUD 9600      
#define FOSC 4000000L
#define NINE 0     /* Use 9bit communication? FALSE=8bit */

#define DIVIDER ((int)(FOSC/(16UL * BAUD) -1))
#define HIGH_SPEED 1

#if NINE == 1
#define NINE_BITS 0x40
#else
#define NINE_BITS 0
#endif

#if HIGH_SPEED == 1
#define SPEED 0x4
#else
#define SPEED 0
#endif

//#if defined(_16F87) || defined(_16F88)
//	#define RX_PIN TRISB2
//	#define TX_PIN TRISB5
//#else
//	#define RX_PIN TRISC7
//	#define TX_PIN TRISC6
//#endif
	#define RX_PIN TRISB1
	#define TX_PIN TRISB2


/* Serial initialization */
#define init_comms()\
	RX_PIN = 1;	\
	TX_PIN = 1;		  \
	SPBRG = DIVIDER;     	\
	RCSTA = (NINE_BITS|0x90);	\
	TXSTA = (SPEED|NINE_BITS|0x20)

void putch(unsigned char);
unsigned char getch(void);
unsigned char getche(void);

#endif

#include <htc.h>
#include <stdio.h>
#include "usart.h"

void 
putch(unsigned char byte) 
{
	/* output one byte */
	while(!TXIF)	/* set when register is empty */
		continue;
	TXREG = byte;
}

unsigned char 
getch() {
	/* retrieve one byte */
	while(!RCIF)	/* set when register is not empty */
		continue;
	return RCREG;	
}

unsigned char
getche(void)
{
	unsigned char c;
	putch(c = getch());
	return c;
}