1 #include "msp430g2553.h"
2 unsigned int rate = 0;
3 unsigned char updown = 1;
4
5 void main(void) {
6
7 WDTCTL = WDT_MDLY_32;
8
9 TACTL = TASSEL1 + TACLR;
10 TACTL |= MC0;
11
12 CCR0 = 20; // PWM周期
13
14 CCTL1 = OUTMOD_7;
15 CCR1 = 0;
16
17 P1DIR |= 0x40; // P1.6 输出
18 P1SEL |= 0x40; // P1.6 TA0
19
20
21 IE1 |= WDTIE;
22 _EINT();
23
24 for (;;) {
25 _NOP();
26 }
27 }
28
29 #pragma vector=WDT_VECTOR
30 __interrupt void interrupt_watchdog_timer(void) {
31
32 CCR1 = rate;
33 if (updown) {
34 rate += 1;
35 if (rate >= 20)
36 updown = 0;
37 }
38 else
39 {
40 rate -= 1;
41 if (rate <= 0)
42 updown = 1;
43 }
44 }
