From goldt@et.byu.edu  Tue Jul  7 20:33:03 1998
Received: from aleve.media.mit.edu by hub.media.mit.edu; (5.65v3.2/1.1/06Jun95-8.2MPM)
	id AA32480; Tue, 7 Jul 1998 20:33:03 -0400
Received: from wormwood.ee.byu.edu (wormwood.ee.byu.edu [128.187.30.54])
	by aleve.media.mit.edu (8.8.7/ML970927) with ESMTP id TAA30127
	for <handyboard@media.mit.edu>; Tue, 7 Jul 1998 19:48:43 -0400 (EDT)
Received: from wormwood (localhost [127.0.0.1]) by wormwood.ee.byu.edu with SMTP (8.7.6/8.7.1) id RAA26916 for <handyboard@media.mit.edu>; Tue, 7 Jul 1998 17:48:42 -0600 (MDT)
Sender: goldt@ee.byu.edu
Message-Id: <35A2B3D9.1260@et.byu.edu>
Date: Tue, 07 Jul 1998 17:48:41 -0600
From: "Timothy B. Gold" <goldt@et.byu.edu>
X-Mailer: Mozilla 3.04Gold (X11; I; HP-UX B.10.20 9000/780)
Mime-Version: 1.0
To: handyboard@media.mit.edu
Subject: Interrupt Handler for Serial communication
Content-Type: multipart/mixed; boundary="------------18CC6AC44E2E"

This is a multi-part message in MIME format.

--------------18CC6AC44E2E
Content-Type: text/plain; charset=us-ascii
Content-Transfer-Encoding: 7bit

Here's a bit of code that will buffer incoming serial information so
that no information will be lost when transmitting to the handy board. 
There are two files: serial_isr.c and serial_isr.asm.  You'll need to
assemble the .asm file using as11_ic, and then both the .c file and the
.icb file need to be loaded onto the handy board.  I'm sure improvements
could be made to the code to clean it up a little, but it's a start (and
I haven't had any problems with it yet).  Enjoy!

--------------18CC6AC44E2E
Content-Type: text/plain; charset=us-ascii; name="serial_isr.c"
Content-Transfer-Encoding: 7bit
Content-Disposition: inline; filename="serial_isr.c"

/* C program to read serial port with interrupt service routine */
/* First version:  Written by Anton Wirsch   20 Nov 1997 */

/*

   Second Version: Written by Tim Gold   27 May 1998
                              BYU Robotics Lab
			      goldt@et.byu.edu        

     Really, the only thing left from the original code are a few
     lines in the .asm file.  Everything else I pretty much had to
     rewrite from scratch to get it to work the way I wanted to.
     But the orignal code by Anton was a very helpful starting point.

  Needed files:   serial_isr.c
                  serial_isr.icb
		  serial_isr.asm (needed to change the buffer size)

  The buffer size here is 32 bytes (probably much larger than it needs
  to be.)  To change the buffer size, do the following:
              1. Change the BUFFER_SIZE constant below to the
	         desired number of bytes.
	      2. Edit the line(s) in the serial_isr.asm which contain
	         the word "EDIT" in the comment so that the value
		 matches that of BUFFER_SIZE.
	      3. Recreate the serial_isr.icb file by typing the following:
	         > as11_ic serial_isr.asm 

 */




#define BUFFER_SIZE 32  /* change buffer size here  -- see above */

/* various constants used by the program... */
#define BAUD 0x102b   /* baud rate set to 9600 */
#define SCCR2 0x102d
#define SCCR1 0x102c
#define SCSR 0x102e
#define SCDR 0x102f

int buffer[BUFFER_SIZE]; /* this is the actual buffer */


void initSerial()
{
  /* Call this routine to activate the serial interrupt handler. */
  int i,temp;

  /* clear out buffer */
  for(i=0; i<BUFFER_SIZE; i++)
    buffer[i] = 0;

  /* clear vairous flags */
  DATA_FLAG = 0;
  INCOMING = 0;
  CURRENT = 0;

  /* pass address of buffer to interrupt routine */
  buffer_ptr = (int) buffer; 
  BASE_ADDR = (int) buffer;
  
  /* activate interrupt routine */
  temp = peek(SCCR2);
  temp |= 0x24;
  poke(SCCR2, temp);
  poke(0x3c, 1);
}

void closeSerial() 
{
  int temp;
  
  /* deactivate the interrupt routine */
  temp = peek(SCCR2);
  temp &= 0xdf;
  poke(SCCR2, temp);
  READ_SERIAL = 0x0000;
  poke(0x3c, 0);

}

void serialPutChar(int c)
{
  /* call this function to write a character to the serial port */

  while (!(peek(0x102e) & 0x80));
  poke(0x102f, c);               

}


int dataAvailable()
{
  /* This function can be used to check to see if any data is available */
  return DATA_FLAG;
}


int serialGetChar()
{
  /* Create blocking getchar for serial port... */
  int return_char;
  
  /* loop until data is available */
  while(!DATA_FLAG);

  /* get the character to return */
  return_char = buffer[CURRENT];

  /* check for wrap around... */
  CURRENT++;
  if(CURRENT == BUFFER_SIZE)
    CURRENT = 0;
  if(CURRENT == INCOMING)
    DATA_FLAG = 0;
  return return_char;

}





--------------18CC6AC44E2E
Content-Type: text/plain; charset=us-ascii; name="serial_isr.asm"
Content-Transfer-Encoding: 7bit
Content-Disposition: inline; filename="serial_isr.asm"

/* This sets up the serial interrupt service routine */
/* First Version:	Written by Anton L. Wirsch  20 Nov 1997 */
/* Second Version: Written by Tim Gold   27 May 1998
                              BYU Robotics Lab
		              goldt@et.byu.edu        

     Really, the only thing left from the original code are a few
     lines in the .asm file.  Everything else I pretty much had to
     rewrite from scratch to get it to work the way I wanted to.
     But the orignal code by Anton was a very helpful starting point.

  Needed files:   serial_isr.c
                  serial_isr.icb
		  serial_isr.asm (needed to change the buffer size)

  The buffer size here is 32 bytes (probably much larger than it needs
  to be.)  To change the buffer size, do the following:
              1. Change the BUFFER_SIZE constant in serial_isr.c to the
	         desired number of bytes.
	      2. Edit the line in this fils which contains
	         the word "EDIT" in the comment so that the value
		 matches that of BUFFER_SIZE.
	      3. Recreate the serial_isr.icb file by typing the following:
	         > as11_ic serial_isr.asm 
*/


/* change this line to match your library path... */
#include "/usr/local/ic/libs/6811regs.asm"

        ORG MAIN_START
variable_CURRENT:
	FDB    00        * ptr to next data to be read by user
	
variable_INCOMING:
        FDB    00        * number of bytes received (circular count)

variable_BASE_ADDR:
	FDB    00        * base address of buffer (to be set by init routine)
	
variable_DATA_FLAG:
        FDB    00        * flag set when data is available

variable_buffer_ptr:     
        FDB    00        * pointer to CURRENT buffer

subroutine_initialize_module:
/* change this line to match your library path... */
#include "/usr/local/ic/libs/ldxibase.asm"

        ldd     SCIINT,X
        std     interrupt_code_exit+1
        ldd     #interrupt_code_start
        std     SCIINT,X
        
	rts

interrupt_code_start:
        ldad    variable_INCOMING       * store INCOMING into AB
        cmpb    #00                     * compare B with 0
        bhi     skip                    * goto "skip" if (B > 0)
        ldx     variable_BASE_ADDR      * STORE ADDRESS OF ARRY IN X
        inx                             * SKIP THE FIRST (?)
        inx                             * TWO BYTES      (?)
        inx                             * OFFSET TO THE HIGHER BYTE (?)
        stx     variable_buffer_ptr     * SAVE PTR VALUE 
        bra     cont

skip:
        ldx     variable_buffer_ptr     * load buffer pointer into x
cont:
        ldad    variable_INCOMING       * load INCOMING into AB
        incb                            * increment INCOMING
	cmpb    #32                     * compare B and 32   --EDIT TO CHANGE BUFFER SIZE--
	beq     reset_count             * if a=32, goto reset_count
	bra     cont1
reset_count:
	ldad    #00                     * set count to zero
cont1:	
        stad    variable_INCOMING       * store AB into INCOMING
        
        ldab    SCSR                    * load SCSR (SCI status register) into B (why?)
        ldab    SCDR                    * load SCSR (SCI data register) into B

        stab    ,X                      * store data in array
        inx                             * increment by two bytes
        inx                             
        stx     variable_buffer_ptr     * save the pointer value
	ldad    #01                     * load 1 into AB
	stad    variable_DATA_FLAG      * store AB into DATA_FLAG (indicating data is available)
interrupt_code_exit:
        jmp     $0000
















--------------18CC6AC44E2E--