time.c

基于LPC2292的发声程序

/******************************************************************************/
/* TIME.C: Time Functions for 100Hz Clock Tick                                */
/******************************************************************************/
/* This file is part of the uVision/ARM development tools.                    */
/* Copyright (c) 2005-2006 Keil Software. All rights reserved.                */
/* This software may only be used under the terms of a valid, current,        */
/* end user licence from KEIL for a compatible version of KEIL software       */
/* development tools. Nothing else gives you the right to use this software.  */
/******************************************************************************/

#include <LPC22XX.H>                          // LPC22XX Peripheral Registers

long volatile timeval;

/* Timer Counter 0 Interrupt executes each 10ms @ 60 MHz CPU Clock */
__irq void tc0 (void) {
  ++timeval;
  T0IR        = 1;                            // Clear interrupt flag
  VICVectAddr = 0;                            // Acknowledge Interrupt
}

/* Setup the Timer Counter 0 Interrupt */
void init_timer (void) {
  T0MR0 = 149999;                             // 10mSec = 150.000-1 counts
  T0MCR = 3;                                  // Interrupt and Reset on MR0
  T0TCR = 1;                                  // Timer0 Enable
  VICVectAddr0 = (unsigned long)tc0;          // set interrupt vector in 0
  VICVectCntl0 = 0x20 | 4;                    // use it for Timer 0 Interrupt
  VICIntEnable = 0x00000010;                  // Enable Timer0 Interrupt
}