timer.c

一个通过8051来控制8019上网的程序 该程序已经通过并成功用于键盘

//-----------------------------------------------------------------------------
// Net TIMER.C
//
// This module sets up the timer and handles the timer interrupt
//-----------------------------------------------------------------------------
#include <reg52.h>
#include "net.h"
#include "timer.h"


extern UINT volatile event_word;
extern ULONG idata initial_sequence_nr;


//--------------------------------------------------------------------------
// Timer 2 interrupt service routing. Intr vector location is
// address 0x002B. The timer generates an interrupt every 25 msec
// It is set to auto reload so do not need to reload it.
//--------------------------------------------------------------------------
void timer1_interrupt(void) interrupt 3
{
	static UINT count1 = 0;
	static UINT count2 = 0;
	
	TH1=0X4C;
	TL1=0;	
	// 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 == 5) event_word |= EVENT_ARP_RETRANSMIT;
	
	if (count1 == 10) event_word |= EVENT_TCP_INACTIVITY;
	
	if (count1 == 15) event_word |= EVENT_READ_ANALOG;
	
	if (count1 == 20)
	{
	 	count1 = 0;
	 	event_word |= EVENT_TCP_RETRANSMIT;
	}
	
	count2++;
	if (count2 == 2401)
	{
		// This happens every 60.025 seconds, not simultaneous
		// with above tasks
		count2 = 0;
		event_word |= EVENT_AGE_ARP_CACHE;
	}
}