main.c

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/************************************************************************************
*																					*
*	File Name	: main.c															*
*	Contents	: Main program of Timer RA Pulse Period Measurement Mode			*
*					sample program for R8C/25 Group									*
*	Copyright(C)2007, Renesas Technology Corp.										*
*	Copyright(C)2007, Renesas Solutions Corp.										*
*	All rights reserved.															*
*	Version		: 2.00																*
*	note		: 1.00	: First version												*
*				: 2.00	: Waiting time for oscillation stabilization added			*
*						: Loop of main process modified to measure pulse period		*
*						: Timer RA interruption process added						*
************************************************************************************/
#include "sfr_r825.h"					/* Definition of the R8C/25 SFR */

/* Definition of RAM area */
unsigned char f_edge = 0;				/* Active edge flag */
unsigned char undf_cnt = 0;				/* Underflow counter */
unsigned char present_tra;				/* Present content of TRA register */
unsigned short measurement_value;		/* Measurement value */

/* Declaration of function prototype */
void timer_ra_init(void);				/* Initial setting of Timer RA SFR */
void TRA_int(void);						/* Timer RA interruption process */

/************************************************************************************
Name:        main
Parameters:  None
Returns:     None
Description: User main
************************************************************************************/
void main(void)
{
	unsigned int i = 0;

	asm("FCLR I");						/* Interrupt disabled */

	/*-----------------------------------------------------------
	-	Set High-speed on-chip oscillator clock to System clock	-
	-----------------------------------------------------------*/
	prc0 = 1;							/* Protect off */
	cm14 = 0;							/* Low-speed on-chip oscillator on */
	fra2 = 0x00;						/* Selects Divide-by-2 mode */
	fra00 = 1;							/* High-speed on-chip oscillator on */
	while(i <= 255) i++;				/* This setting is an example of waiting time for the */
										/* oscillation stabilization. Please evaluate the time */
										/* for oscillation stabilization by a user. */
	fra01 = 1;							/* Selects High-speed on-chip oscillator */
	cm16 = 0;							/* No division mode in system clock division */
	cm17 = 0;
	cm06 = 0;							/* CM16 and CM17 enable */
	prc0 = 0;							/* Protect on */

	/*-----------------------------------
	-	Initialize Timer RA SFR			-
	-----------------------------------*/
	timer_ra_init();					/* Initial setting of Timer RA SFR */

	asm("FSET I");						/* Interrupt enable */

	/*-----------------------------------
	-	Loop of main					-
	-----------------------------------*/
	while(1){							/* Main processing */
		if ( f_edge == 1 ) {			/* Active edge received ? */
			if ( undf_cnt == 0 ){		/* Timer RA underflows ? */
				measurement_value = 0xFF - present_tra;
			} else {
				measurement_value = (0x0100*undf_cnt) + 0xFF - present_tra;
				undf_cnt = 0;			/* Underflow counter cleared */
			}
			f_edge = 0;					/* Active edge flag cleared */
		}
	}
}
/************************************************************************************
Name:        timer_ra_init
Parameters:  None
Returns:     None
Description: Initial setting of Timer RA SFR
************************************************************************************/
void timer_ra_init(void)
{
	unsigned int i = 0;

	pd1 &= 0x7F;						/* P1_7(TRAIO):Input mode */
	tstart_tracr = 0;					/* Stop Timer RA operation */
	while(tcstf_tracr != 0);			/* Count stop ? */
	traic = 0x00;						/* Disable Timer RA Interrupt */
	tstop_tracr = 1;					/* The TRAPRE and TRA registers are initialized. */
										/* The TSTART and TCSTF bits in the TRACR register */
										/* are initialized too. */
	/* Timer RA prescaler underflow : 40MHz * f2(FRA2) * f8(TCK2-TCK0) * 25 = 10us */
	trapre = 25 - 1;					/* Set (25 - 1) in TRAPRE register */
	tra = 0xFF;							/* Set 0xFF in TRA register */
	tracr = 0x00;						/* Set timer ra control regsiter */
										/* TEDGF : Active edge not received */
										/* TUNDF : No underflow */
	traioc = 0x00;						/* Set timer ra i/o control register */
										/* Measures measurement pulse from one rising edge */
										/* to next rising edge */
										/* Select INT1/TRAIO pin (P1_7) */
										/* TRAIO input filter : No filter */
	tramr = 0x14;						/* Set timer ra mode register */
										/* Pulse period measurement mode */
										/* Timer RA Count Source : f8 */
										/* Provides count source */
	traic = 0x07;						/* Set Timer RA interrupt Control Register */
										/* Interrupt priority level is set to level 7 */
	tstart_tracr = 1;					/* Start Timer RA operation */
	while(tcstf_tracr != 1);			/* During count ? */
	while(i <= 255) i++;				/* When using the pulse period measurement mode, */
										/* leave two periods or more of Timer RA prescaler */
										/* immediately after count starts, */
	tracr = 0x21;						/* then set the TEDGF bit to "0". */
}
/************************************************************************************
Name:        TRA_int
Parameters:  None
Returns:     None
Description: Timer RA interruption process
************************************************************************************/
#pragma INTERRUPT TRA_int
void TRA_int(void)
{
	if ( tedgf_tracr != 0 ) {			/* Active edge received? */
		tracr = 0x01;					/* When set to "0" by a program, use a MOV instruction */
										/* to write "0" to the TEDGF bit and the TUNDF bit */
										/* in the TRACR register. */
		present_tra = tra;				/* Read tra register */
		f_edge = 1;						/* Active edge flag set */
	}
	if ( tundf_tracr != 0 ) {			/* Timer RA underflows? */
		tracr = 0x11;					/* When set to "0" by a program, use a MOV instruction */
										/* to write "0" to the TUNDF bit in the TRACR register. */
										/* At the same time, write "1" to the TEDGF bit */
										/* in the TRACR register. */
		undf_cnt++;						/* Underflow counter increment */
	}
}