MSP430另一种UART实现
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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 }
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