msp430x22x4_ta_20.c

430成都技术培训会代码

//******************************************************************************
//  MSP430F22x4 Demo - Timer_A, PWM TA1-2, Up/Down Mode, 32kHz ACLK
//
//  Description: This program generates two PWM outputs on P1.2,3 using
//  Timer_A configured for up/down mode. The value in TACCR0, 128, defines the
//  PWM period/2 and the values in TACCR1 and TACCR2 the PWM duty cycles. Using
//  32kHz ACLK as TACLK, the timer period is 7.8ms with a 75% duty cycle on
//  P1.2 and 25% on P1.3. Normal operating mode is LPM3.
//  ACLK = TACLK = LFXT1 = 32768Hz, MCLK = default DCO ~1.2MHz
//  //* External watch crystal on XIN XOUT is required for ACLK *//
//
//               MSP430F22x4
//            -----------------
//        /|\|              XIN|-
//         | |                 | 32kHz
//         --|RST          XOUT|-
//           |                 |
//           |         P2.3/TA1|--> TACCR1 - 75% PWM
//           |         P2.4/TA2|--> TACCR2 - 25% PWM
//
//  A. Dannenberg
//  Texas Instruments Inc.
//  April 2006
//  Built with IAR Embedded Workbench Version: 3.42F
//******************************************************************************
#include "msp430x22x4.h"

void main(void)
{
  WDTCTL = WDTPW + WDTHOLD;                 // Stop WDT
  BCSCTL3 |= LFXT1S_2;                      // LFXT1 = VLO  
  P2DIR |= 0x18;                            // P2.3 and P2.4 output
  P2SEL |= 0x18;                            // P2.3 and P2.4 TA1/2 otions
  TACCR0 = 12800/5;                             // PWM Period/2
  TACCTL1 = OUTMOD_6;                       // TACCR1 toggle/set
  TACCR1 = 3200/5;                              // TACCR1 PWM duty cycle
  TACCTL2 = OUTMOD_6;                       // TACCR2 toggle/set
  TACCR2 = 9600/5;                              // TACCR2 PWM duty cycle
  TACTL = TASSEL_1 + MC_3;                  // ACLK, up-down mode

  __bis_SR_register(LPM3_bits);             // Enter LPM3
}