timer.c

单片机控制RTL8019AS的程序,C语言编写,仿真通过.

//-----------------------------------------------------------------------------
// Net TIMER.C
//
// This module sets up the timer and handles the timer interrupt
//-----------------------------------------------------------------------------
#include <reg51.h>
#include <net.h>
#include <timer.h>


extern UINT volatile event_word;
extern ULONG idata initial_sequence_nr;

sfr T2CON               = 0xc8;
sbit cprl2              = T2CON^0;
sbit ct2                = T2CON^1;
sbit TR2                = T2CON^2;
sbit exen2              = T2CON^3;
sbit tclk               = T2CON^4;
sbit rclk               = T2CON^5;
sbit exf2               = T2CON^6;
sbit TF2                = T2CON^7;

sfr RCAP2H              = 0xcb;
sfr RCAP2L              = 0xca;
sfr TH2                 = 0xcd;
sfr TL2                 = 0xcc;

sfr CHPCON              = 0xbf;
sfr CHPENR              = 0xf6;
sfr SFRAL               = 0xc4;
sfr SFRAH               = 0xc5;
sfr SFRFD               = 0xc6;
sfr SFRCN               = 0xc7;

//--------------------------------------------------------------------------
// Timer 2 interrupt service routing. Intr vector location is
// address 0x002B. The timer generates an interrupt every 20 msec
// It is set to auto reload so do not need to reload it.
//--------------------------------------------------------------------------
void timer2_interrupt(void) interrupt 5
{
	static UINT count1 = 0;
	static UINT count2 = 0;
	
	TF2 = 0;		// Clear interrupt flag

	
	// Advance the initial sequence number
	initial_sequence_nr += 6250;
   // Keep it some distance from rolling over
   if (initial_sequence_nr & 0x10000000L) initial_sequence_nr = 1;
	
	count1++;
	// These events happens every 0.50 seconds, not simultaneously
	if (count1 == 6) event_word |= EVENT_ARP_RETRANSMIT;
	
	if (count1 == 12) event_word |= EVENT_TCP_INACTIVITY;
		
	if (count1 == 25)
	{
	 	count1 = 0;
	 	event_word |= EVENT_TCP_RETRANSMIT;
	}
	
	count2++;
	if (count2 == 3001)
	{
		// This happens every 60.020 seconds, not simultaneous
		// with above tasks
		count2 = 0;
		event_word |= EVENT_AGE_ARP_CACHE;
	}
}





//--------------------------------------------------------------------------
// Setup Timer2 in mode 1 which is 16 bit auto reload
// Intr rate = 32 MHz /(12 * (65536 - reload value))
// For 20 msec reload value  = 0x2FAB
//--------------------------------------------------------------------------
void init_timer2(void)
{
	T2CON = 0x00;
	RCAP2H = 0x2F; 		// Reload value
	RCAP2L = 0xAB;
	TH2 = 0x2F;				// Initial load value
	TL2 = 0xAB;
	TR2 = 1;					// Timer 2 run
}