Xilinx Webpack

[mep]

Hi there
I teach classes in VHDL and uses Xilinx Webpack as a tool for this.
Unfortunately, the new module wizard always set type std_logic for
I/O-lines. This makes it very hard to learn the students about the other
types.
Does anybody know if this can be changed - and how?
Mogens

 

[Mike Treseler]

Hi there
I teach classes in VHDL and uses Xilinx Webpack as a tool for this.
Unfortunately, the new module wizard always set type std_logic for
I/O-lines. This makes it very hard to learn the students about the other
types.

Consider using the Modelsim program included
with webpack to teach VHDL language.

-- Mike Treseler

 

[mep]

Hi Mike
Not really, because in all the drills, the students end up programming a
CPLD or a FPGA from Xilinx. In this way they can themselves check the
solutions.
But maybe I should take a closer look, because there are a number of
problems with webpack.
Mogens

 

[Alex Gibson]

Hi Mike
Not really, because in all the drills, the students end up programming a
CPLD or a FPGA from Xilinx. In this way they can themselves check the
solutions.
But maybe I should take a closer look, because there are a number of
problems with webpack.
Mogens

Easy to copy the code from in modelsimand paste it back into project
navigator.
Or use the add a copy of the source feature in
the module wizard and in project navigator.

We use the full version of ise in the lab
(via university program http://university.xilinx.com/ )
and students have webpack to use at home.

If you have problems with webpack go here
http://xup.msu.edu/support/index.htm

Surely it is up to the instructor to
teach them about all the types in vhdl not the module wizard ?

Could always set a few small assignments where they have to use
some of the other types or give them a limit on the number
of std_logic I/Os they can use.


Alex

 

[Laurent Gauch]

skip any wizard !
Your students need to learn the basic of VHDL and NOT the software troubles.

You can provide some VHDL generic code of DFF, shift register, counter ...

For a nice VHDL memo goto http://www.amontec.com/fix/vhdl_memo/index.html

Larry

 

[rickman]

skip any wizard !
Your students need to learn the basic of VHDL and NOT the software troubles.

You can provide some VHDL generic code of DFF, shift register, counter ...

For a nice VHDL memo goto http://www.amontec.com/fix/vhdl_memo/index.html

I don't see a default type in a wizard as "troubles". Sure the GUI
stuff will have more bugs than simpler software, but the GUI is what
most people use and it is not unreasonable to use it in a classroom. I
especially like the idea of not making students spend time typing in
lists of signals several times for module definitions. I prefer that
they learn the basics of how to use an HDL and how to code. I almost
never start from scratch in my VHDL. I copy from an old module and just
change the names. I even have defined editor macros to allow me to type
in the signal names once and do a search and replace to change the list
to the other formats, component declarations and instantiations.

Why make the students do a lot of work they won't be doing in the real
world? I hated that sort of make-work when I was in school.

--

Rick "rickman" Collins

(e-mail address removed)
Ignore the reply address. To email me use the above address with the XY
removed.

Arius - A Signal Processing Solutions Company
Specializing in DSP and FPGA design URL http://www.arius.com
4 King Ave 301-682-7772 Voice
Frederick, MD 21701-3110 301-682-7666 FAX

 

[Mike Treseler]

I don't see a default type in a wizard as "troubles".

The trouble is non-portable code and vendor-specific libraries.

Sure the GUI
stuff will have more bugs than simpler software, but the GUI is what
most people use and it is not unreasonable to use it in a classroom. I
especially like the idea of not making students spend time typing in
lists of signals several times for module definitions.

I agree that the students should have an editor that can
copy ports and paste signal lists, instances and testbench templates.
The point is that they ought to be learning how to
infer registers, counters, shifters and RAMs from portable VHDL code,
not wiring up magic boxes.

By learning simulation first, the students can eliminate
errors and verify the module's function before attempting
synthesis. In a simulation environment, you can jump
to syntax errors and trace code for debugging.

-- Mike Treseler

 

[Martin Bishop]

In my experience, if you use anything other than Std_Logic(_Vector) for IOs
from a device your Vital simulation wont work; plain fact. Therefore Xilinx
are simply following "best" practice.

Equally, I would take a lot of persuasion that any types beyond
Std_Logic(_Vector), Std_ULogic (for resolved signal implementations),
Unsigned, Signed, enumerated types, and perhaps a few "specials" have a
serious role in synthesis.

Martin

 

[mpe]

Hi Mike,

<not wiring up magic boxes>. magic or black! You hit the nail on the head..
I know persons, that argues that it is not nessary to learn types ( and
sensitivity list and a lot more that I fell basic). Give the students 10-15
templates and scematic in webpack and you have a beginners course!

Maybe we should start a group discussing the pensum for a XX-lessons
beginners course. And courses to follow!

I feel simulation - even (or especially) on a beginners course - is very
important. It teaches the students a lot, but mostly being systematic, set
goals and reach them!

mogens

 

[Laurent Gauch]

I don't see a default type in a wizard as "troubles". Sure the GUI
stuff will have more bugs than simpler software, but the GUI is what
most people use and it is not unreasonable to use it in a classroom. I
especially like the idea of not making students spend time typing in
lists of signals several times for module definitions. I prefer that
they learn the basics of how to use an HDL and how to code. I almost
never start from scratch in my VHDL. I copy from an old module and just
change the names. I even have defined editor macros to allow me to type
in the signal names once and do a search and replace to change the list
to the other formats, component declarations and instantiations.

Why make the students do a lot of work they won't be doing in the real
world? I hated that sort of make-work when I was in school.

Yes I'm OK with you.
But it is still depending on the student level and where is the VHDL
'Real World'.

VHDL 'real world' may be :
- VHDL RTL design
- VHDL System design
- (testbench)

RTL design is bottom-up concept
System design is top-down concept

So, the 'Real world'(industrial project) is somewhere between
'bottom-up' and 'top-down' concept.

Now, with students, is this better to start with RTL Design or System
design?

For me, it is still better to start with RTL design -> for better
Hardware understandings.

Larry
www.amontec.com

 

[rickman]

The trouble is non-portable code and vendor-specific libraries.

What code is non-portable just because it is generated by a wizard? I
am not familiar with this wizard, but genrating a boiler plate module
from a list of IOs does not sound very problimatic to me.

I agree that the students should have an editor that can
copy ports and paste signal lists, instances and testbench templates.
The point is that they ought to be learning how to
infer registers, counters, shifters and RAMs from portable VHDL code,
not wiring up magic boxes.

You are talking about something different I believe. That would be
instantiated modules and FSM generators. Very different from what was
being discussed.

By learning simulation first, the students can eliminate
errors and verify the module's function before attempting
synthesis. In a simulation environment, you can jump
to syntax errors and trace code for debugging.

Yes, but they need to be *taught* about synthesis and I always recommend
that they design the logic structure before they start *any* coding or
simulation.

--

Rick "rickman" Collins

(e-mail address removed)
Ignore the reply address. To email me use the above address with the XY
removed.

Arius - A Signal Processing Solutions Company
Specializing in DSP and FPGA design URL http://www.arius.com
4 King Ave 301-682-7772 Voice
Frederick, MD 21701-3110 301-682-7666 FAX