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问下,看定时器A那部分的时候,用软仿还是硬仿,在增计数模式下,tar的值都没达到ccr0的设定值就出现中断,怎么回事啊
源程序:
//******************************************************************************
// MSP-FET430P140 Demo - Timer_A, Toggle P3.4, CCR0 Up Mode ISR, DCO SMCLK
//
// Description: Toggle P3.4 using software and TA_0 ISR. Timer_A is
// configured for up mode, thus the timer overflows when TAR counts
// to CCR0. In this example, CCR0 is loaded with 20000.
// ACLK = n/a, MCLK = SMCLK = TACLK = default DCO ~800kHz
//
// MSP430F149
// ---------------
// /|\| XIN|-
// | | |
// --|RST XOUT|-
// | |
// | P3.4|-->LED
//
// Dasheng
// LiTian Electronic Inc.
// Feb 2008
// Built with IAR Embedded Workbench Version: 3.42A
//******************************************************************************
#include <msp430x14x.h>
void main(void)
{
WDTCTL = WDTPW + WDTHOLD; // Stop WDT
P3DIR |= BIT4; // P3.4 output
CCTL0 = CCIE; // CCR0 interrupt ena××ed
CCR0 = 20000;
TACTL = TASSEL_2 + MC_1; // SMCLK, upmode
_BIS_SR(LPM0_bits + GIE); // Enter LPM0 w/ interrupt
}
// Timer A0 interrupt service routine
#pragma vector=TIMERA0_VECTOR
__interrupt void Timer_A (void)
{
P3OUT ^= BIT4; // Toggle P3.4
}
这是怎么回事啊?
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