t0_m1_c_gh.c

C51 TIMER 0的使用 Timer_0_mode_1_counter_gate_hard

/**
 * @file $RCSfile: t0_m1_c_gh.c,v $
 *
 * Copyright (c) 2004 Atmel.
 *
 * Please read file license.txt for copyright notice.
 *
 * @brief This file is an example to use timer0 in mode 1.
 *
 * This file can be parsed by Doxygen for automatic documentation
 * generation.
 * Put here the functional description of this file within the software
 * architecture of your program.
 *
 * @version $Revision: 1.0.0 $ $Name:  $
 */

/* @section  I N C L U D E S */
#include "reg_c51.h"

/**
 * FUNCTION_PURPOSE: This file set up timer 0 in mode 1 (16 bits counter) 
 * with a hardware gate. The counter count up at eatch negative transition.
 * The 16-bits register consist of all 8 bits of TH0 and all 8 bits   
 * of TL0.   
 * FUNCTION_INPUTS: P3.2(INT0)=1 : GATE Input
 *                  P3.4(T0) must be controlled by an external clock
 * FUNCTION_OUTPUTS: void
 */
void main(void)
{
	TMOD &= 0xF0;					/* Timer 0 mode 0 counter with hardware gate */
	TMOD |= 0x0D;					/* GATE0=1; C/T0#=1; M10=0; M00=1; */
	
	TH0 = 0x00;					   /* init values */
	TL0 = 0x00;		
	ET0=1;							/* enable timer0 interrupt */
	EA=1;								/* enable interrupts */
	TR0=1;							/* timer0 run */
	while(1);						/* endless  */
}


/**
 * FUNCTION_PURPOSE: timer0 interrupt
 * FUNCTION_INPUTS: void
 * FUNCTION_OUTPUTS: P1.0 toggle period = 2 * 65536 * P3.4(T0) period  
 */
void it_timer0(void) interrupt 1 /* interrupt address is 0x000b */
{
	TF0 = 0;							/* reset  interrupt flag (already done by hardware)*/
	P1_0 = ~P1_0;					/* P1.0 toggle when interrupt. */
}