Linux Reading Data from UART

Question

I want to read data from UART, i followed this tutorial, the write function works as expected, however i\'am getting problem with the read function :

This is the uart_in

Answer 1

Your program is hanging in the read() syscall because it is blocked waiting for a line-termination character.
You tried to configure the port for non-canonical mode with the statement

SerialPortSettings.c_iflag &= ~(ICANON | ECHO | ECHOE | ISIG);  /* Non Cannonical mode  

but that operation is on the wrong termios element.
The ICANON attribute is part of the lflag element (and not the iflag). (This error originates from the tutorial you referenced!)
Therefore your program is performing blocking canonical reads.

There's a convenient termios function for configuring non-canonical mode:

   cfmakeraw()  sets the terminal to something like the "raw" mode of the old 
   Version 7 terminal driver: input is available character by
   character, echoing is disabled, and all special processing of  
   terminal  input  and  output  characters  is  disabled.   The  terminal
   attributes are set as follows:

       termios_p->c_iflag &= ~(IGNBRK | BRKINT | PARMRK | ISTRIP
                       | INLCR | IGNCR | ICRNL | IXON);
       termios_p->c_oflag &= ~OPOST;
       termios_p->c_lflag &= ~(ECHO | ECHONL | ICANON | ISIG | IEXTEN);
       termios_p->c_cflag &= ~(CSIZE | PARENB);
       termios_p->c_cflag |= CS8;