msp430x20x3_ta_20.s43

来自「LSD-EZ430-F2013在IAR环境下的汇编语言开发例程」· S43 代码 · 共 47 行

;*******************************************************************************
;   MSP430F20xx Demo - Timer_A, PWM TA1-2, Up/Down Mode, 32kHz ACLK
;
;   Description: This program generates one PWM output on P1.2 using
;   Timer_A configured for up/down mode. The value in CCR0, 128, defines
;   the PWM period/2 and the value in CCR1 the PWM duty cycle.
;   Using 32kHz ACLK as TACLK, the timer period is 7.8ms with a 75% duty
;   cycle on P1.2. Normal operating mode is LPM3.
;   ACLK = TACLK = LFXT1 = 32768Hz, MCLK = default DCO.
;   //* External watch crystal on XIN XOUT is required for ACLK *//	
;
;                MSP430F20xx
;             -----------------
;         /|\|              XIN|-
;          | |                 | 32kHz
;          --|RST          XOUT|-
;            |                 |
;            |         P1.2/TA1|--> CCR1 - 75% PWM
;
;   M. Buccini / L. Westlund
;   Texas Instruments Inc.
;   October 2005
;   Built with IAR Embedded Workbench Version: 3.40A
;*******************************************************************************
#include  "msp430x20x3.h"
;-------------------------------------------------------------------------------
            ORG     0F800h                  ; Program Reset
;-------------------------------------------------------------------------------
RESET       mov.w   #0280h,SP               ; Initialize stackpointer
StopWDT     mov.w   #WDTPW+WDTHOLD,&WDTCTL  ; Stop WDT
SetupP1     bis.b   #00Ch,&P1DIR            ; P1.2 and P1.3 output
            bis.b   #00Ch,&P1SEL            ; P1.2 and P1.3 TA1/2 otions
SetupC0     mov.w   #128,&CCR0              ; PWM Period/2
SetupC1     mov.w   #OUTMOD_6,&CCTL1        ; CCR1 toggle/set
            mov.w   #32,&CCR1               ; CCR1 PWM Duty Cycle	
SetupTA     mov.w   #TASSEL_1+MC_3,&TACTL   ; ACLK, updown mode
                                            ;					
Mainloop    bis.w   #LPM3,SR                ; Enter LPM3
            nop                             ; Required only for debugger
                                            ;
;-------------------------------------------------------------------------------
;           Interrupt Vectors
;-------------------------------------------------------------------------------
            ORG     0FFFEh                  ; MSP430 RESET Vector
            DW      RESET                   ;
            END