XC164CS-32 port problems

Don't use _getkey. It is the function gets calls to read one character. You have eliminated the echoing of the characters but _getkey still clears the receive interrupt flag, which should not be done when using the receive FIFO.

Don't use printf either (or putchar which printf calls). They do things you don't expect, like check and read a received character when they see a '\r' or '\n'.

If your application really is such that you don't have to do anything else while waiting for a message from the PC or sending a message to the PC, I recommend polling the serial interface directly yourself, both when receiving and sending. Instead of using printf you can use sprintf, which does exactly and only what it is expected to do.

Sauli

Don't use _getkey. It is the function gets calls to read one character. You have eliminated the echoing of the characters but _getkey still clears the receive interrupt flag, which should not be done when using the receive FIFO.

Don't use printf either (or putchar which printf calls). They do things you don't expect, like check and read a received character when they see a '\r' or '\n'.

If your application really is such that you don't have to do anything else while waiting for a message from the PC or sending a message to the PC, I recommend polling the serial interface directly yourself, both when receiving and sending. Instead of using printf you can use sprintf, which does exactly and only what it is expected to do.

Sauli

Sauli,

Talk about limiting on what can be done on the serial port!

Are you suggesting something like this?

while (((char)ASC0_RBUF != '\n') && (count < 11) )
{
        // read the buffer??
        temp_string[count] = (char)ASC0_RBUF;
        // clear the buffer??
        ASC0_RXFCON = 0x0607;
        count++;
}

temp_string[count] = '\0';

but then that causes a problem because it will NEVER get the rest of the data from the RS232 stream and it's like filling up the first character and ignoring the rest.

How would you then write something up like this using the FIFO buffer to get the received data?

Curiously, do you know the size for the Receive buffer?

Steve

Check the datasheet about the registers for the serial port.

You do not read out a character just to check if there is a character. If there is, then your while loop will loose that character.

There are specific flags to check if there are one or more characters available to read, and if there is room to insert at least one more character to send. Use them, when polling the serial port.

And skip the space characters. Just refuse to insert them in your buffer, since you would just have to spend time throwing them away later. If you want to know how many space characters you have received before the actul data, you can count the number of spaces thrown away since the previous newline character was received.

By the way, your chip does not need to be "warmed up". All it needs is enough time for the crystal to get a stable frequency, and that any used PLL gets time to lock into the correct frequency. Depending on hardware, that takes milliseconds up to maybe a second.

You really should figure it out yourself, but you can try out these to prove yourself that the serial interface actually does work. It took me a few minutes to write them and I certainly have not tested them, not even compiled. From experience I know that it is all too easy to put in a mistake in the most simple piece of code.

unsigned int receive_line( char *buf, unsigned int bufsize)
{
   unsigned int count;

   /* Cannot read anything into a nonexistent or
      zero sized buffer. */
   if( ( buf == NULL) || (bufsize == 0))
   {
      return 0;
   }

   /* Must have space for the terminating NUL. */
   bufsize--;

   /* Read no more characters than fits in the buffer. */
   for( count = 0; count < bufsize; count++)
   {
      /* Wait for a character. */
      while( (ASC0_FSTAT & 0x0F) == 0)
      {
         ;
      }

      /* Read it to the buffer. */
      buf[ count] = ASC0_RBUF;

      /* If newline, we are done.
         Newline is not saved. */
      if( buf[ count] == '\n')
      {
         break;
      }
   }

   /* Terminate the line. */
   buf[ count] = '\0';

   /* Return number of characters read. */
   return count;
}

void send_line( char *buf)
{
   /* Cannot send anything from a nonexistent buffer. */
   if( buf != NULL)
   {
      /* While not end of string.. */
      while( *buf != '\0')
      {
         /* Wait for room in the transmit FIFO. */
         while( (ASC0_FSTAT & 0xF00) == 0x800)
         {
            ;
         }




         /* Send the character. */
         ASC0_TBUF = *buf++;
      }
   }
}

After you have these working, you could start figuring out how to do it with interrupts. Sooner or later you will want to do something useful with the time wasted in these two routines.

Sauli