MSP430另一种UART实现

1 #include "msp430g2553.h"

2

3 typedef unsigned char uchar;

4 typedef unsigned int uint;

5

6 #define LED BIT0

7 #define TXD BIT1 // TXD on P1.1

8 #define RXD BIT2 // RXD on P1.2

9 #define POUT P1OUT

10

11 #define BITTIME_1b 13*4 //1bit宽度

12 #define BITTIME_1b5 13*6 //1.5bit宽度

13

14 uchar bitcnt;

15 uint uart_buf;

16 int Send_flag;

17

18 uchar *str=" Hello EEWorld! r";

19

20 void FaultRoutine(void)

21 {

22 while(1); // 异常挂起

23 }

24

25 void ConfigClocks(void)

26 {

27 if (CALBC1_1MHZ ==0xFF || CALDCO_1MHZ == 0xFF)

28 FaultRoutine(); // If calibration data is erased

29 // run FaultRoutine()

30 BCSCTL1 = CALBC1_1MHZ; // Set range

31 DCOCTL = CALDCO_1MHZ; // Set DCO step + modulation

32 BCSCTL3 |= LFXT1S_2; // LFXT1 = VLO

33 IFG1 &= ~OFIFG; // Clear OSCFault flag

34 BCSCTL2 = 0; // MCLK = DCO = SMCLK

35 }

36

37 void ConfigPins(void)

38 {

39 P1DIR |= TXD+LED;

40 P1DIR &= ~RXD; // P1.3 input, other outputs

41 P1OUT |= TXD; // clear output pins

42

43 }

44

45

46 //发送一个字节

47 void send_char(uchar tchar)

48 {

49 TACTL = TACLR + TASSEL_2 + ID_3; //选择SMCLK时钟;清TAR

50 CCR0 = BITTIME_1b5; //crr0定时间隔为1bit时间宽度

51 CCTL0 |= CCIE; //打开CCR0中断

52 bitcnt = 10; //待发送的位数

53 uart_buf = 0x0100; //8+N+1

54 uart_buf |= tchar; //stop bit and start bit;

55 uart_buf <<=1;

56 Send_flag = 0;

57 TACTL |= MC_1; //Start TA, UP mode.

58 _BIS_SR(GIE);

59 while(!Send_flag); //wait until send complete

60 Send_flag = 1;

61 }

62

63 //发送一个字符串

64 void send_String(uchar *tstr)

65 {

66 while(*tstr)

67 send_char(*tstr++);

68 }

69

70

71 void send_IRQ(void)

72 {

73 if(bitcnt>0)

74 {

75 if(uart_buf & 0x01)

76 POUT |= TXD;

77 else

78 POUT &= ~TXD;

79 uart_buf >>= 1;

80 bitcnt--;

81 }

82 else

83 {

84 TACTL &= ~MC_3; //Close the TA when a Byte send over. ??

85 CCTL0 &= ~CCIE; //关闭CCR0中断

86 Send_flag = 1;

87 }

88

89 }

90

91

92

93 void main( void )

94 {

95 // Stop watchdog timer to prevent time out reset

96 uint i;

97

98

99

100 WDTCTL = WDTPW + WDTHOLD;

101 ConfigClocks();

102 ConfigPins();

103

104

105 while(1)

106 {

107 send_String(str);

108

109 for(i=50000;i>0;i--);

110 for(i=50000;i>0;i--);

111 for(i=50000;i>0;i--);

112 for(i=50000;i>0;i--);

113 POUT ^= LED; // 翻转LED

114 }

115 }

116

117 // Timer A0 interrupt service routine

118 #pragma vector=TIMER0_A0_VECTOR

119 __interrupt void Timer_A (void)

120 {

121

122

123 send_IRQ();

124 }