linux 串口可以接收数据,不能发送

byhoo123

如题,经检查Write函数的返回值是不为-1的.

1. #include     <stdio.h>      /*标准输入输出定义*/
   
2. #include     <stdlib.h>     /*标准函数库定义*/
   
3. #include     <unistd.h>     /*Unix标准函数定义*/
   
4. #include     <sys/types.h>  /**/
   
5. #include     <sys/stat.h>   /**/
   
6. #include     <fcntl.h>      /*文件控制定义*/
   
7. #include     <termios.h>    /*PPSIX终端控制定义*/
   
8. #include     <errno.h>      /*错误号定义*/
   
9. #define FALSE 0
   
10. #define TRUE 1
    
11. int set_Parity(int fd,int databits,int stopbits,int parity)
    
12. {
    
13. struct termios options;
    
14. if  ( tcgetattr( fd,&options)  !=  0)
    
15. {
    
16.   perror("SetupSerial 1");     
    
17.   return(FALSE);  
    
18. }
    
19. options.c_cflag &= ~CSIZE;
    
20. options.c_lflag  &= ~(ICANON | ECHO | ECHOE | ISIG);  /*Input*/
    
21. options.c_oflag  &= ~OPOST;     /*Output*/
    
22. // options.c_iflag   &= ~IXON;         //0x11
    
23. // options.c_iflag   &= ~ICRNL;        //0x0d
    
24. //  options.c_cflag|=CLOCAL;
    
25. //  options.c_cflag|=CREAD;
    
26. //  options.c_cflag&=~CRTSCTS;   /*T*/
    
27.   
    
28. switch (databits) /*y*/
    
29. {   
    
30. case 7:           
    
31.   options.c_cflag |= CS7;
    
32.   break;
    
33. case 8:     
    
34.   options.c_cflag |= CS8;
    
35.   break;   
    
36. default:   
    
37.   fprintf(stderr,"Unsupported data size\n"); return (FALSE);  
    
38. }
    
39. switch (parity)
    
40. {   
    
41. case 'n':
    
42. case 'N':   
    
43.   options.c_cflag &= ~PARENB;   /* Clear parity enable */
    
44.   options.c_iflag &= ~INPCK;     /* Enable parity checking */
    
45.   break;  
    
46. case 'o':   
    
47. case 'O':     
    
48.   options.c_cflag |= (PARODD | PARENB); /* éè???a??D§?é*/  
    
49.   options.c_iflag |= INPCK;             /* Disnable parity checking */
    
50.   break;  
    
51. case 'e':  
    
52. case 'E':   
    
53.   options.c_cflag |= PARENB;     /* Enable parity */   
    
54.   options.c_cflag &= ~PARODD;   /* ×a???a??D§?é*/     
    
55.   options.c_iflag |= INPCK;       /* Disnable parity checking */
    
56.   break;
    
57. case 'S':
    
58. case 's':  /*as no parity*/   
    
59.   options.c_cflag &= ~PARENB;
    
60.   options.c_cflag &= ~CSTOPB;
    
61.   break;  
    
62. default:   
    
63.   fprintf(stderr,"Unsupported parity\n");   
    
64.   return (FALSE);  
    
65. }  
    
66. /*stopbits*/  
    
67. switch (stopbits)
    
68. {   
    
69. case 1:   
    
70.   options.c_cflag &= ~CSTOPB;  
    
71.   break;  
    
72. case 2:   
    
73.   options.c_cflag |= CSTOPB;  
    
74.   break;
    
75. default:   
    
76.   fprintf(stderr,"Unsupported stop bits\n");  
    
77.   return (FALSE);
    
78. }
    
79. /* Set input parity option */
    
80. if (parity != 'n')
    
81. {   
    
82.   options.c_iflag |= INPCK;
    
83. }
    
84. tcflush(fd,TCIFLUSH);
    
85. options.c_cc[VTIME] = 0; /* seconds*/   
    
86. options.c_cc[VMIN] = 1; /* define the minimum bytes data to be readed*/
    
87. if (tcsetattr(fd,TCSANOW,&options) != 0)   
    
88. {
    
89.   perror("SetupSerial 3");   
    
90.   return (FALSE);  
    
91. }
    
92. return (TRUE);  
    
93. }
    
94. void set_speed(int fd, int speed)
    
95. {
    
96. int   i;
    
97. int   status;
    
98. struct termios   Opt;
    
99. tcgetattr(fd, &Opt);
    
100. int speed_arr[] = { B115200,B38400, B19200, B9600, B4800, B2400, B1200, B300,
     
101.       B38400, B19200, B9600, B4800, B2400, B1200, B300, };
     
102. int name_arr[] = { 115200,38400,  19200,  9600,  4800,  2400,  1200,  300, 38400,  
     
103.       19200,  9600, 4800, 2400, 1200,  300, };
     
104. for ( i= 0;  i < sizeof(speed_arr) / sizeof(int);  i++)
     
105. {
     
106.   if  (speed == name_arr[i])
     
107.   {
     
108.    tcflush(fd, TCIOFLUSH);     
     
109.    cfsetispeed(&Opt, speed_arr[i]);  
     
110.    cfsetospeed(&Opt, speed_arr[i]);   
     
111.    status = tcsetattr(fd, TCSANOW, &Opt);  
     
112.    if  (status != 0)
     
113.    {
     
114.     perror("tcsetattr fd");  
     
115.     return;     
     
116.    }
     
117.    tcflush(fd,TCIOFLUSH);   
     
118.   }  
     
119. }
     
120. }
     
121. /**
     
122. *@breif 打开串口
     
123. */
     
124. int OpenDev(char *Dev)
     
125. {
     
126. int fd = open( Dev, O_RDWR | O_NOCTTY);         // | O_NDELAY
     
127. if (-1 == fd)
     
128.   { /*设置数据位数*/
     
129.    perror("Can't Open Serial Port");
     
130.    return -1;
     
131.   }
     
132. else
     
133. return fd;
     
134. }
     
135. /**
     
136. *@breif  main()
     
137. */
     
138. int main(int argc, char **argv)
     
139. {
     
140. int fd;
     
141. int nread;
     
142. int nr;
     
143. char buffer[512]="Hello";
     
144. char buff[512];
     
145. char *dev ="/dev/ttyS1";
     
146. 
     
147. fd = OpenDev(dev);
     
148. if (fd>0)
     
149.   set_speed(fd,9600);
     
150. else
     
151. {
     
152.   printf("Can't Open Serial Port!\n");
     
153.   exit(0);
     
154. }
     
155. if (set_Parity(fd,8,1,'N')== FALSE)
     
156. {
     
157.   printf("Set Parity Error\n");
     
158.   exit(1);
     
159. }
     
160.   
     
161.   nr = write(fd, buffer ,4);
     
162.   printf("write data is %d\n", nr);
     
163.   while(1)
     
164.    {
     
165.      while((nread = read(fd,buff,512))>0)
     
166.      {
     
167.         printf("Len %d,",nread);
     
168.   //      nread = write(fd,buff,512);
     
169.         buff[nread+1]='\0';
     
170.         printf("%s\n",buff);
     
171.       }
     
172.    }
     
173.     //close(fd);
     
174.     //exit(0);
     
175. }
     

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byhoo123

自己顶下.希望知道的能回答下,谢谢!

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