MSP430 G2553 比较器Comparator_A+、数据流程图DFD、状态转换图STD

 1 #include "io430.h"
 2 
 3 #define LED1 BIT0  //red
 4 
 5 #define TRUE 1
 6 #define FALSE 0
 7 
 8 #define LOW_INPUT 0
 9 #define HIGH_INPUT 1
10 
11 //global variable
12 char state = LOW_INPUT;
13 char flash = FALSE; //start with low input, no flash on LED
14 
15 void main(void)
16 {
17     // Stop watchdog timer to prevent time out reset
18     WDTCTL = WDTPW + WDTHOLD;
19     
20     // LED setup
21     P1OUT = 0;
22     P1DIR |= LED1;
23     
24     // DCO setup
25     BCSCTL1 = CALBC1_1MHZ; //running at 1MHz
26     DCOCTL = CALDCO_1MHZ;
27     
28     // ACLK setup
29     BCSCTL3 |= LFXT1S_2; //ACLK source: VLO, measured as 10kHz
30     BCSCTL1 |= DIVA_3; //ACLK = VLO divided by 8: 1.25kHz
31     
32     // Timer0_A setup
33     TA0CCR0 = 250 - 1; //timer overflow freq: 1250/250 = 5Hz(0.2s)
34     TA0CCTL0 = CCIE;//enable interrupt
35     TA0CTL = TASSEL_1 + MC_1 + TACLR;//ACLK, no div, up mode, clear timer
36     
37     // Comparator_A+ setup
38     CACTL1 = CAREF_2 + CARSEL + CAIE;//0.5 Vcc ref on V-, enable interrupt on rising
39     CACTL2 = P2CA4 + CAF; //input CA1 (P1.1) on V+, filter on
40     CACTL1 |= CAON; //turn on comparator
41     
42     __enable_interrupt();
43     LPM3;
44     
45 }
46 
47 #pragma vector = TIMER0_A0_VECTOR
48 __interrupt void CCR0_ISR(void)
49 {
50     //TA0CCR0 flag clearing is automatic
51     if(flash == FALSE)
52     {
53         P1OUT &= ~LED1; //led off
54     }
55     else
56     {
57         P1OUT ^= LED1; //toggle LED
58     }
59 }
60 
61 #pragma vector = COMPARATORA_VECTOR
62 __interrupt void COMPA_ISR(void)
63 {
64     switch(state)
65     {
66     case LOW_INPUT:
67         if((CACTL2 & CAOUT) == 0x01)
68         {
69             state = HIGH_INPUT;
70             CACTL1 |= CAIES; //value high, so watch for falling edge
71             flash = TRUE; //let led flash      
72         }
73         break;
74     case HIGH_INPUT:
75         if((CACTL2 & CAOUT) == 0x00)
76         {
77             state = LOW_INPUT;
78             CACTL1 &= ~CAIES; //value low, so watch for rising edge
79             flash = FALSE; //turn LED off      
80         }
81         break;      
82     }
83 }