msp430x42x0_ta_16.c

msp430单片机系统开发子源码

//*******************************************************************************
//   MSP430x42x0 Demo - Timer_A, PWM TA1-2 Up Mode, DCO SMCLK
//
//  Description: This program outputs two PWM signals on P1.2 and P1.3 using
//  Timer_A configured for up mode. The value in CCR0 defines the PWM period
//  and the values in CCR1 and CCR2 the PWM duty cycles. Using SMCLK as TACLK,
//  the timer period is 488us with a 75% duty cycle on P1.2 and 25% on P1.3.
//  ACLK = LFXT1 = 32768Hz, MCLK = SMCLK = default DCO = 32 x ACLK = 1048576Hz
//  //* An external watch crystal between XIN & XOUT is required for ACLK *//	
//
//               MSP430F4270
//            -----------------
//        /|\|              XIN|-
//         | |                 | 32kHz
//         --|RST          XOUT|-
//           |                 |
//           |         P1.2/TA1|--> CCR1 - 75% PWM
//           |         P1.3/TA2|--> CCR2 - 25% PWM
//
//  L. Westlund / S. Karthikeyan
//  Texas Instruments Inc.
//  June 2005
//  Built with IAR Embedded Workbench Version: 3.30A
//*****************************************************************************
#include  <msp430x42x0.h>

void main(void)
{
  WDTCTL = WDTPW +WDTHOLD;                  // Stop WDT
  FLL_CTL0 |= XCAP14PF;                     // Configure load caps
  P1DIR |= 0x0C;                            // P1.2,3 output
  P1SEL |= 0x0C;                            // P1.2 TA1 option, P1.3 TA2
  CCR0 = 512-1;                             // PWM Period
  CCTL1 = OUTMOD_7;                         // CCR1 reset/set
  CCR1 = 384;                               // CCR1 PWM duty cycle
  CCTL2 = OUTMOD_7;                         // CCR2 reset/set
  CCR2 = 128;                               // CCR2 PWM duty cycle
  TACTL = TASSEL_2 + MC_1;                  // SMCLK, up mode

  _BIS_SR(LPM0_bits);                       // Enter LPM0
}