I am a newbie.  I have spent much time reading web resourecs / FAQ's /
"Programming and Customizing the PIC.." etc. before bothering the list.


I am trying to use the interrupt driven serial i/o routines provided in
Myke Predko's book "Programming and Customizing the PIC Microcontroller"

The file provided is "serial.inc"

For my first test, I wanted to include this file in an existing program,
assemble and run.  The idea was to change only one thing at a time.

1.  _VarEnd variable used in "serial.inc" caused problems for the
assembler.  I haven't found any documentation regarding this var, so I had
to make assumptions.  I am assuming that I am supposed to declare this
variable and set it to the first usable address space in the register
file.

2. The code toward the end of "serial.inc"

  movlw  Bit                    ;  Delay for the Bit
  movwf  Count
  decfsz Count
  goto  $ - 1

caused problems:  "Count" not defined.  So, I changed it BitCount out of
desperation.

3.  Once I got that to assemble properly, I had errors with address
conflicts for the program memory(I think)

It appears that the code declared in the "serial.inc" file had been
assigned to program memory locations starting at 0000, and later in my
main program:

  org 0

  bsf    STATUS, RP0
  bcf    TRISA & 0x07F, 1

which causes some sort of conflict with the addressing.  So, I changed:

org 0

org 0x001D  (I think that's what it was)

and this conflict went away.

4.  Now when I assemble, I get no errors, but I can't seem to get my
program to execute as before.  (ie without the  serial I/O stuff)



Overall I feel like I am in the dark.  I feel like I don't have an idea of
what the assembler does, what it considers legal syntax  (for example,
what is the meaning of "PAGE" at the beginning of the program?) and I'm
not even sure I have a good / compelete guide to the valid PIC instruciton
set.


MY GOAL:

Write a simple program / circuit that listens to incoming serial data from
PC via IR, and echo's back the same data to the PC via IR.  I have been
able to make the IR part work for receiving codes from Sony remote
control.


Any help on using MPASM, PIC instruction set, or rs-232 style serial I/O
would be appreciated.


Also, any suggestions to linux bases devel tools would be GREATLY
APPRECIATED.  I am sick of windows.


Thanks.

-Steve

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