Tutorial week 3

• Redhat Linux has a program minicom that can read and write to the serial port, and also set port parameters. Using this (or the more common stty), connect two PCs using the null modem cables, and set both to 9600baud, 8 data bits, 1 stop bit and exchange data
• The lecture notes for devices have code to read from a serial port. Write a program to read from standard input and write to the serial port. The program should stop when end-of-file is encountered on input (user types ctrl-d)
  • Use the standard C library call

    
    	    char *fgets(char *string, int str_length, FILE *fp)
    	    

    where the string is an array of char, and fp is stdin. End of file is signalled by the function returning NULL:

    
    	    char str[128];
    	    while (fgets(str, 128, stdin) != NULL) ...
    	    

  • Use the POSIX function call

    
    	    int write(int file_descriptor, char *string, int str_len)
    	    

    where the file_descriptor is the file descriptor from opening the serial port, 0 and the string is an array of char. The value returned is the number of characters read

    
    	    char str[128];
    	    write(0, str, 128); 
    	    

• Using the null-modem cables, link the serial ports of two PCs together, and use the C program to send data to the Java program
• Based on the C program to read from the serial port, write a program in Java to read from the serial port and write to standard ouput