MSP430 P1.1 P1.2 P1.3 第二功能
發(fā)布時間：2008-10-22 22:33
發(fā)布者：
MSP430
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定時器A在UP模式、CONTINUE 模式、UP/DOWN模式下，不利用中斷程序即可在P1.1 P1.2 P1.3 管腳上輸出所設(shè)定值的頻率，并且在UP/DOWN模式下時，頻率計算與前兩種模式下不同，因?yàn)閁P/DOWN模式下，CCIFG 是在TACCRX-1到TACCRX變化時，置1的，而TAIFG是在1到0置1的、
例程序：
//******************************************************************************
// MSP-FET430P140 Demo - Timer_A, Toggle P1.1/TA0, Up Mode, DCO SMCLK
//
// Description: Toggle P1.1 using hardware TA0 output. Timer_A is configured
// for up mode with CCR0 defining period, TA0 also output on P1.1. In this
// example, CCR0 is loaded with 500-1 and TA0 will toggle P1.1 at TACLK/500.
// Thus the output frequency on P1.1 will be the TACLK/1000. No CPU or
// software resources required.
// As coded with TACLK = SMCLK, P1.1 output frequency is ~800000/1000.
// SMCLK = MCLK = TACLK = default DCO ~800kHz
//
// MSP430F149
// -----------------
// /|\| XIN|-
// | | |
// --|RST XOUT|-
// | |
// | P1.1/TA0|--> SMCLK/1000
//
// M. Buccini
// Texas Instruments Inc.
// Feb 2005
// Built with IAR Embedded Workbench Version: 3.21A
//修改時間:2008.8.20 am 8:13
// only timera 依靠DCO工作，而CPU 停止工作。
//******************************************************************************
#include
void main(void)
{
WDTCTL = WDTPW + WDTHOLD; // Stop WDT
P1DIR |= 0x02; // P1.1 output
P1SEL |= 0x02; // P1.1 option select
CCTL0 = OUTMOD_4; // CCR0 toggle mode
CCR0 = 500-1;
TACTL = TASSEL_2 + MC_1; // SMCLK, upmode
_BIS_SR(CPUOFF); // CPU off
}
//******************************************************************************
// MSP-FET430P140 Demo - Timer_A, Toggle P1.1/TA0, Up/Down Mode, 32kHz ACLK
//
// Description: Toggle P1.1 using hardware TA0 output. Timer_A is configured
// for up/down mode with CCR0 defining period, TA0 also output on P1.1. In
// this example, CCR0 is loaded with 5 and TA0 will toggle P1.1 at TACLK/2*5.
// Thus the output frequency on P1.1 will be the TACLK/20. No CPU or software
此處的說明與DATASHEET中的圖不符合，并且DATASHEET中的圖不是太懂
// resources required. Normal operating mode is LPM3.
// As coded with TACLK = ACLK, P1.1 output frequency = 32768/20 = 1.6384kHz
// ACLK = TACLK = 32kHz, MCLK = default DCO ~800kHz
// //* External watch crystal installed on XIN XOUT is required for ACLK *//
//
// MSP430F149
// -----------------
// /|\| XIN|-
// | | | 32kHz
// --|RST XOUT|-
// | |
// | P1.1|-->TA0 ACLK/20
//
// M. Buccini
// Texas Instruments Inc.
// Feb 2005
// Built with IAR Embedded Workbench Version: 3.21A
//******************************************************************************
#include
void main(void)
{
WDTCTL = WDTPW + WDTHOLD; // Stop WDT
P1DIR |= 0x02; // P1.1 output
P1SEL |= 0x02; // P1.1 option select
CCTL0 = OUTMOD_4; // CCR0 toggle mode
CCR0 = 5;
TACTL = TASSEL_1 + MC_3; // ACLK, up-downmode
_BIS_SR(LPM3_bits); // Enter LPM3
}
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