Hello!
I'm having some trouble getting serial communication running reliable on my
BBB. I've used code mostly based on this page
<http://www.tldp.org/HOWTO/Serial-Programming-HOWTO/x115.html> following
the non-canonical input section.
It's up and running, and I can echo anything I send back with read, write,
and shorting the TX and RX pins. The problem I'm having is if I do this
multiple times in one instance of the program, on the third time my board
hangs on the read command. Does anyone have any idea where a good place to
start solving this issue would be?
I've tried using "tcflush(SERIAL_fd,TCIFLUSH);" to clear everything out
after each read under the assumption that this is some kind of buffer
overflow, but that doesn't seem to do anything at all. Here are the
relevant sections of my code, thanks!
void SERIAL_Init(void)
{
/*******************************************************************/
printf("\tSerial Port Initialization ...");
SERIAL_fd = open(MODEMDEVICE,O_RDWR | O_NOCTTY /*| O_NDELAY*/);
if (SERIAL_fd < 0)
{ perror(MODEMDEVICE);
exit(-1);
}
fcntl(SERIAL_fd,F_SETFL,0);
tcgetattr(SERIAL_fd,&newtio);
newtio.c_cflag |= CS8 | CLOCAL | CREAD ;
cfsetispeed(&newtio,BAUDRATE);
cfsetospeed(&newtio,BAUDRATE);
newtio.c_iflag = IGNBRK | IGNPAR;
newtio.c_oflag = 0;
newtio.c_lflag = 0;
newtio.c_cc[VTIME]=0; /* inter-character timer unused */
newtio.c_cc[VMIN]=31; /* blocking read until 18 chars
received */
tcflush(SERIAL_fd,TCIFLUSH);
tcsetattr(SERIAL_fd,TCSANOW,&newtio);
/****************************************************************/
printf("Done\n");
return;
}
...and then in main without all the other code I'm adding this too....
//Read from maestro command, 1a2b is a test command strictly for echoing
unsigned char read_command[2][2] = {
{0x1a,0x2b},
{0x90,0x05},
};
unsigned char test_data[2] = {0x00,0x00};
...here's where the actual read and write calls happen...
while(readTest == 0)
{
printf("Enter 0 to read from maestro pin, 1 to continue with testing\n");
scanf("%d",&readTest);
write(SERIAL_fd,read_command[0],2);
printf("Wrote values...\n");
num_bytes = read(SERIAL_fd,&test_data,2);
printf("Value read: %x %x\n",test_data[0],test_data[1]);
}
Any help would be greatly appreciated! If there's anything else you need
from me in order to help just let me know! Thanks!
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