Multiple UART

nopnop2002

Ashtonites replied at 2016-7-7 02:17
I have a related question, so I'm not opening a new thread:
The hardware to which my OPi UART is con ...

Here is Man Page of cfsetospeed function.
http://linux.die.net/man/3/cfsetispeed

cfsetospeed() sets the output baud rate stored in the termios structure pointed to by termios_p to speed, which must be one of these constants:

B0
B50
B75
B110
B134
B150
B200
B300
B600
B1200
B1800
B2400
B4800
B9600
B19200
B38400
B57600
B115200
B230400

The zero baud rate, B0, is used to terminate the connection. If B0 is specified, the modem control lines shall no longer be asserted. Normally, this will disconnect the line. CBAUDEX is a mask for the speeds beyond those defined in POSIX.1 (57600 and above). Thus, B57600 & CBAUDEX is nonzero.
cfgetispeed() returns the input baud rate stored in the termios structure.

cfsetispeed() sets the input baud rate stored in the termios structure to speed, which must be specified as one of the Bnnn constants listed above for cfsetospeed(). If the input baud rate is set to zero, the input baud rate will be equal to the output baud rate.

cfsetspeed() is a 4.4BSD extension. It takes the same arguments as cfsetispeed(), and sets both input and output speed.


I think I can't set it as 250000 baud rate.

bigmac

By the way you need to ask your hardware the supported baudrate in order to see if above can be set. ( normally 50, 75, 110, 134, 150, 200, 300, 600, 1200, 1800, 2400, 4800, 9600, 19200, 38400, 57600, 115200)

some USB 2 RS232 may do the trick
http://www.prolific.com.tw/US/ShowProduct.aspx?pcid=41

nopnop2002

I tried two serial communication at the same time.
It's work fine.

1. //
   
2. // Serial Receive Program
   
3. //
   
4. // cc -o serialR serialR.c -lwiringPi
   
5. //
   
6. #include <stdio.h>
   
7. #include <string.h>
   
8. #include <errno.h>
   
9. #include <wiringPi.h>
   
10. #include <wiringSerial.h>
    
11. 
    
12. #define    DEBUG    0
    
13. 
    
14. int readSerial(int fd, char * buff, int blen, int timeout) {
    
15.   unsigned long endTime;
    
16.   int ch;
    
17.   int pos = 0;
    
18. 
    
19. if(DEBUG)printf("millis=%d\n",millis());
    
20.   endTime = millis () + timeout;
    
21. if(DEBUG)printf("endTime=%d\n",endTime);
    
22.   buff[pos] = 0;
    
23. 
    
24.   while (1) {
    
25.     if (millis () > endTime) return -1;
    
26.     if (serialDataAvail (fd)) {
    
27.       ch = serialGetchar (fd);
    
28. if(DEBUG)printf (" -> %02x\n", ch);
    
29.       if (ch == 0x0d) {
    
30. 
    
31.       } else if (ch == 0x0a) {
    
32.         return pos;
    
33.       } else {
    
34.         if (pos < blen) buff[pos++] = ch;
    
35.         if (pos < blen) buff[pos] = 0;
    
36.       }
    
37.     } // end if
    
38.   } // end while
    
39. }
    
40. 
    
41. 
    
42. int main (int argc, char **argv) {
    
43.   int fd1;
    
44.   int fd2;
    
45.   int len;
    
46.   char buff[64];
    
47.   char device1[32];
    
48.   char device2[32];
    
49. 
    
50.   memset(device1,0,sizeof(device1));
    
51.   memset(device2,0,sizeof(device2));
    
52. 
    
53.   strcpy(device1,"/dev/ttyAMA0");
    
54.   if (argc >= 2) strcpy(device1,argv[1]);
    
55.   if (argc >= 3) strcpy(device2,argv[2]);
    
56.   printf("device1=[%s] device2=[%s]\n",device1,device2);
    
57. 
    
58.   if ((fd1 = serialOpen (device1, 115200)) < 0) {
    
59.     printf ("Unable to open serial device1: %s\n", strerror (errno)) ;
    
60.     return 1 ;
    
61.   }
    
62. 
    
63.   if (strlen(device2) > 0) {
    
64.     if ((fd2 = serialOpen (device2, 115200)) < 0) {
    
65.       printf ("Unable to open serial device2: %s\n", strerror (errno)) ;
    
66.       return 1 ;
    
67.     }
    
68. 
    
69.   }
    
70. 
    
71.   if (wiringPiSetup () == -1) {
    
72.     printf ("Unable to start wiringPi: %s\n", strerror (errno)) ;
    
73.     return 1 ;
    
74.   }
    
75.   printf("wiringPiSetup\n");
    
76. 
    
77.   while(1) {
    
78. //  Receive data
    
79.     len=readSerial(fd1, buff, sizeof(buff),100);
    
80.     if (len != -1) {
    
81.       printf("readSerial(device1) data=[%s]\n",buff);
    
82. //    Send data
    
83.       serialPrintf (fd1,"You are Welcome!! This is %s\n",device1);
    
84.     }
    
85. 
    
86.     len=readSerial(fd2, buff, sizeof(buff),100);
    
87.     if (len != -1) {
    
88.       printf("readSerial(device2) data=[%s]\n",buff);
    
89. //    Send data
    
90.       serialPrintf (fd2,"You are Welcome!! This is %s\n",device2);
    
91.     }
    
92.   }
    
93. }

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