G'day,

If any of you aim for perfection in the reduction of static file
register usage, I have some more code for you, adding to my data stack
architecture that I introduced previously.  The data stack is built
using the PIC's FSR register as a pointer to a downward-growing stack
of bytes.  By expressing the interface of all important functions in
stack semantics, it becomes easier to write more code.  Programmers
who have used the FORTH language will find some of this work familiar.

The new code is a simple uptimer, counting days, hours, minutes and
seconds since the microcontroller was turned on, and displaying the
data on an LCD panel.

New stack architecture functions introduced are:

- LCD display access, put a data byte or a command on stack and call
  the function,

- vectored execution, put a pointer to a function on the stack and
  call the function,

- data table handler, give it a pointer to the table function, a
  pointer to a function to be called for each table entry, and call
  the function,

- binary coded decimal conversion, nice wasteful code that takes a
  high and a low byte of a 16-bit word on the stack, and returns three
  bytes of binary coded decimal,

- hexadecimal conversion, takes a byte and returns two ASCII
  characters on the stack.

The code is licensed under the GNU Public License.  Duplication to
www.piclist.com welcome.

http://quozl.netrek.org/uptime/ is the new code,
http://quozl.netrek.org/stack-math.asm is my prior work.

P.S. One 16F877 died during testing; I slipped and delivered 26V DC to
somewhere on the PCB, without much current limit.  Now when powered up
the PIC pulls about 200mA.  Took out an LCD display and a MAX232 at the
same time.  The PIC is dead, isn't it?

Root cause ... I bought some of Don's DT106 known-faulty boards
without the SIMM edge connector exposed, and used it as a floating
board on top of a DT001 programmer, with header pins instead of using
the edge connector.  Used the five-wide programming jumpers.  I didn't
insulate under the board.  One of the SIMM pins has the unregulated
supply.  Ouch.  Sigh.

--
James Cameron    mailto:quozl@us.netrek.org     http://quozl.netrek.org/

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