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'Looking For Help about Intel Instruction Set !!'
1997\12\29@231705 by Carlos Gruber

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face
Esteemed colleagues:

       I'm new to PIC. Recently I download data sheet, aplication notes and
programming instructions for the
12cxx and 16c5x devices from Microchip Home page. I hope use it in real
aplications soon, but I need first buy
the programming hardware and software. This doesn't mean I'm not interesting in
the piclist, for the contrary,
I need your comments and recomendation for my present and future work.
       Actually I'm working in projects involving the parallel PC port. I need
to use
it for prototype and for
communication purposes, but I have a problem: I can not get precise timing using
the Intel instruction set
because I don't know how long is each instruction and how many clock cycles are
necesary for its ejecution. In
the data sheet of 8086 family are a brief instruction set sumary but it not
include information detailed
(Syntax, operands, operation, status affected, encoding, description, words,
cycles, and examples)

       Somebody of your know a list, usenet or a web addres useful for me?

Thanks in advance

Carlos Gruber.
U.N.E.X.P.O
Pto Ordaz, Venezuela.

1997\12\30@031145 by bam-mon

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Carlos Gruber wrote:
>
> Esteemed colleagues:
>
>         I'm new to PIC. Recently I download data sheet, aplication notes and
>  programming instructions for the
> 12cxx and 16c5x devices from Microchip Home page. I hope use it in real
>  aplications soon, but I need first buy
> the programming hardware and software. This doesn't mean I'm not interesting
in
>  the piclist, for the contrary,
> I need your comments and recomendation for my present and future work.
>         Actually I'm working in projects involving the parallel PC port. I
need to use
>  it for prototype and for
> communication purposes, but I have a problem: I can not get precise timing
using
>  the Intel instruction set
> because I don't know how long is each instruction and how many clock cycles
are
{Quote hidden}

Dear Mr. Gruber,
as I read in your mail to the PIC-LIST, you are looking for a
PIC-programmer
Maybe we can help with a complete programmer ?  Our P16PGD is able to
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--
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 Systeme fuer Wissenschaft und Technik
   Am Postmoor 36 * D-28719 Bremen
               Germany
Fon +49-421-646775 * Fax +49-421-646785

e-mail :  spam_OUTbam-monTakeThisOuTspamgit-online.de

1997\12\30@082719 by jrmont

picon face
Carlos Gruber wrote:

I can not get precise timing using
>  the Intel instruction set
> because I don't know how long is each instruction and how many clock cycles
are
>  necesary for its ejecution. In
> the data sheet of 8086 family are a brief instruction set sumary but it not
>  include information detailed
> (Syntax, operands, operation, status affected, encoding, description, words,
>  cycles, and examples)
>
Somebody of your know a list, usenet or a web addres useful for me?
>

Carlos,

I do not recommend that you use SW loops that depend on instruction
clock cycles for your timing loops. This is very complex in with an
Intel CPU because of the instruction piplining, memory wait states and
varying clock speeds. There are three better ways.

1) Learn to use one of the PCs internal timers to produce an interrupt
at known intervals. You will need to dig into the PC HW and Peripheral
chip programming specs for this. I have used this method in a DOS
application successfully many years ago and do not remember all of the
details. If you choose to go this route and have specific questions, I
can help you.

2) Put a convenient reference clock on your external circuit and connect
it to a Parallel port input pin so that it can be polled. Your SW can
count multiples of this clock rising and falling to create longer
delays. Steve Marshon does this on his PIC16C84 programmer. I have used
this in one of my projects as well.

3) Same as two, but connect the signal to a parallel port pin that can
generate an IRQ to the PC on each clock cycle.


I am sorry that I cannot be more specific without going back and doing
some research. If you tell me more about your application, I can help
you some more.

1) How many of the pins on the port must you use for your application.
(Ins and Outs)

2) What kind of time delays are you looking for.

3) Are you building the external HW, or are you stuck with something
that exists.

4) Is your program DOS or Windows? (3.1, 95, or NT).

Good Luck
John Montalbano

1997\12\30@092841 by SLandas

picon face
I agree that its a bad idea to use loops or software that depend on
instructions cycle times for timing. There is another way to do this. The PC
generates an INT8 every
1/18.2 (about 54.9 ms) to update the real time clock. When its done with the
RTC in generates an INT 1C. INT1C doesn't do anything except a RTI. You can
take over this interrupt and execute your own code. You just need to be
careful that INT8 + INT 1C(your code) don't take longer than 54.9 ms to
execute. If you need a time base other than this you'll need to look for
another method.


Steve


'Looking For Help about Intel Instruction Set !!'
1998\01\11@045022 by paulb
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Steve Landas wrote:

> I agree that its a bad idea to use loops or software that depend on
> instructions cycle times for timing.  There is another way to do this.
> The PC generates an INT 8 every 1/18.2 (about 54.9 ms) to update the
> real time clock.  When its done with the RTC it generates an INT 1C.
> INT 1C doesn't do anything except a RTI.  You can take over this
> interrupt and execute your own code.  You just need to be careful that
> INT 8 + INT 1C(your code) don't take longer than 54.9 ms to execute.
>  If you need a time base other than this you'll need to look for
> another method.

 Well, this approach is fine for occasions when a time "granularity" of
18.2Hz suits, but often a millisecond or finer resolution is needed.
There is still a proper way to do this in a completely processor-
independent fashion and it is rather easy.  The timer which produces the
18.2Hz interrupt IS readable, albeit with some difficulty on later
silicon (I DO invite anyone who has a good explanation of this problem
to contribute here!  I understand it IS fixable).

 Timing is implemented by reading the timer value, calculating a
"compare" value and proceeding to loop reading the timer and comparing
it until the target is reached or exceeded (overflow considerations
apply).  With certain limitations, other tasks such as checking for
keypresses, even asynchronous (i.e., other than isosynchronous) tasks
can be performed within the loop.

 We are talking about writing programming algorithms for PICs, aren't
we?  This would be the obvious way to go about it.  Of course, it is
unlikely this will work properly with Windoze but then, no software
approach will.  An interesting hardware approach involves using a spare
serial port and interrupt (with buffers disabled) as a programmable
interrupt timer.  Subverting the main clock "tick" timer interrupt ˆ l‡
GWBASIC or certain games is NOT recommended and under Windoze, not
possible.

 Cheers,
       Paul B.

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