P,r Ligander <PICLIST@MITVMA.MIT.EDU> wrote:

> Does anyone know what a register stimulus file should look like ?? I
> have tried with a plain dos test file with one hex value for each
> row as the manual for the dos version of mpsim says but I get weird
> values. I cant find any information in MPLAB's helpfile. Some values
> are right but the first ones are allways wrong. Should there be some
> kind of header in the file ????

Pelle:

First, make sure that you are using the latest version of the
simulator (version 5.20).  If you don't have it, you can obtain it
from Microchip's BBS (telnet:mchipbbs.microchip.com); it's in the
"Released" File Library, along with the MPSIM User's Guide and User's
Guide Addendum, both of which you should also obtain.

Regular, periodic clock signals can be simulated by using the "CK"
command:

    "CK" displays the current clock assignment.
    "CK pin, hi, lo" defines the clock period on a pin.
    "CK pin, -" disables the clock on that pin.

"pin" is the name of an I/O pin and "hi" and "lo" are the number of
instruction cycles that the pin should be hi and lo.  For instance:

    CK RC0, 5, 4        assigns a clock to RC0 with a 9-cycle
                        period (5 cycles high, 4 cycles low).

    CK RC0, -           cancels that simulated clock.

If you need to simulate waveforms that are not this regular, you can
do so using a "stimulus file".  Stimulus files are simple ASCII text
files that look like this:

STEP    RB7  RC0   RA2
1       0    0     0
5       1    0     0
20      1    0     1
21      0    0     0

... etc.

The headings in the first line are important:  The first one must be
"STEP", and the remaining ones show which pins are to be stimulated.

In each of the following lines, the first number is the "step count"
(more on this later) and the other numbers are the values to be placed
on the pins.  There is no limit to the length of a stimulus file, nor
to the number of pins that it can stimulate.

The "step count" defaults to the instruction step.  That is, the above
stimulus file will execute the first line when the first instruction
is executed, the second line when the 5th instruction is executed, the
third line when the 20th instruction is executed, etc.

Since some instructions (GOTO, CALL, etc.) take two cycles rather than
one, this may lead to unexpected results, since the simulator is using
instruction counts rather than absolute time.

To remedy this, Microchip has added the "IP" command.  It sets the
bahavior of stimulus files thusly:

    "IP" displays the current mode.
    "IP step" sets the mode to "count steps".
    "IP time" sets the mode to "count time".

    "step" and "time" are literal strings... To set the
    mode to "time", the command is actually "IP time".

Note that, even if you use the "IP" command to set the mode to
"time", the first column heading in your stimulus file must still be
"STEP".

After creating the stimulus file, you load your source code into MPSIM
as usual, then load the stimulus file using "ST filename".

Hope this helps...

-Andy

Andrew Warren - fastfwd@ix.netcom.com
Fast Forward Engineering, Vista, California
http://www.geocities.com/SiliconValley/2499