CODEWITHSUNDEEP
cserial-portcommunication
Joe Chavis
Joe Chavis

Reputation: 103

Echoing characters to a serial port in C

I am attempting to use C to echo characters from a pic32 processor to a terminal emulator via a serial port. The user would be prompted to enter a string and all that happens is that the characters would appear on the screen as the user typed. This is only to set up an initial program that could later be used for real time menu selections from the user. Example below:

main()
{
   // 1. init the console serial port
   initU2();

   // 2. text prompt
   clrscr();
   home();    
   fputs("Enter some text: ", stdout);
   puts(stdout);

   // 3. main loop
   while (1)
   {
      // 3.1 read a full line of text
      getsn(stdout, sizeof(stdout));
      // 3.2 send a string to the serial port
      puts(stdout);
   } // main loop
} // main

Here is what I get at the command line(regardless of input from the user or not):

Enter some text: ÿÿÿÿ

I can simply echo characters to the terminal program display however if I need to have the user type characters in, the C program doesn't seem to respond. Any help would be appreciated!

Upvotes: 1

Views: 614

Answers (1)

David Grayson
David Grayson

Reputation: 87396

You wrote:

fputs("Enter some text: ", stdout);
puts(stdout);

I think your call to puts is invalid. In normal C libraries puts expects to be passed a pointer to a string, but you are passing stdout to it, which is NOT a string. As a result, you are seeing some junk characters get transmitted on the serial port.

Try either removing the puts lines or changing your code to this:

puts("Enter some text: ");

Upvotes: 3

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