PLD suggestions for classroom use

[stephen.craven@gmail.com]

All,

I am teaching an intro digital logic lab. In past semesters I used the
final assignments to introduce students to structural Verilog netlists
using Spartan 3E boards.

As the class size has outgrown my Spartan boards and I feel that a
modern FPGA is overkill for the simple circuits they are building, I
am looking for a different solution and would appreciate your
suggestions.

My goals:
(1) A cheap reprogrammable PLD / FPGA (~$10 or less),
(2) A DIP package suitable for use in a breadboard, and
(3) A simple tool suite that supports an HDL (preferably Verilog).

Are these mutually exclusive desires? I am willing to tolerate an
expensive programmer.

Thanks!
Stephen

 

[John Adair]

Stephen

Sounds like you want either a mid range CPLD or a low end FPGA. We
don't do it as DIL but have a look at what we do on our Polmaddie
family. Headers are all 0.1 inch/2.54mm aligned. Devices on these are
chosen for cost and to fit the 2 layer PCB target we had to keep costs
down. Details of this family http://www.enterpoint.co.uk/polmaddie/polmaddie_family.html.

Maybe too complicated but also look at
http://www.enterpoint.co.uk/component_replacements/craignell.html.

All of these solutions are supported by free, or low cost, software
and we have reasonable cost programmers for most of them.

If you have a large class it's also viable to do something semi-custom
depending on what you need.

John Adair
Enterpoint Ltd.

On Feb 16, 4:08 pm, "stephen.cra...@gmail.com"
<stephen.cra...@gmail.com> wrote:

All,

I am teaching an intro digital logic lab. In past semesters I used the
final assignments to introduce students to structural Verilog netlists
using Spartan 3E boards.

As the class size has outgrown my Spartan boards and I feel that a
modern FPGA is overkill for the simple circuits they are building, I
am looking for a different solution and would appreciate your
suggestions.

My goals:
(1) A cheap reprogrammable PLD / FPGA (~$10 or less),
(2) A DIP package suitable for use in a breadboard, and
(3) A simple tool suite that supports an HDL (preferably Verilog).

Are these mutually exclusive desires? I am willing to tolerate an
expensive programmer.

Thanks!
Stephen

 

[Tim Wescott]

On 02/16/2011 08:08 AM, stephen.craven@gmail.com wrote:

All,

I am teaching an intro digital logic lab. In past semesters I used the
final assignments to introduce students to structural Verilog netlists
using Spartan 3E boards.

As the class size has outgrown my Spartan boards and I feel that a
modern FPGA is overkill for the simple circuits they are building, I
am looking for a different solution and would appreciate your
suggestions.

My goals:
(1) A cheap reprogrammable PLD / FPGA (~$10 or less),
(2) A DIP package suitable for use in a breadboard, and
(3) A simple tool suite that supports an HDL (preferably Verilog).

Are these mutually exclusive desires? I am willing to tolerate an
expensive programmer.

Just a thought:

I recently had a conversation with the son of a friend of mine. He was
taking a logic class, and had some questions about how to do things. He
remarked that this was his second class, and that the first ended up
being more about how to shoe-horn logic into teeny little devices rather
than learning the language.

Knowing how to shoe-horn logic into small spaces is an essential skill,
but I think it's something you want to impose on people _after_ you've
given them a chance to play in a _big_ sand box.

--

Tim Wescott
Wescott Design Services
http://www.wescottdesign.com

Do you need to implement control loops in software?
"Applied Control Theory for Embedded Systems" was written for you.
See details at http://www.wescottdesign.com/actfes/actfes.html

 

[malcolm]

On Feb 17, 5:08 am, "stephen.cra...@gmail.com"
<stephen.cra...@gmail.com> wrote:

All,

I am teaching an intro digital logic lab. In past semesters I used the
final assignments to introduce students to structural Verilog netlists
using Spartan 3E boards.

As the class size has outgrown my Spartan boards and I feel that a
modern FPGA is overkill for the simple circuits they are building, I
am looking for a different solution and would appreciate your
suggestions.

My goals:
(1) A cheap reprogrammable PLD / FPGA (~$10 or less),
(2) A DIP package suitable for use in a breadboard, and
(3) A simple tool suite that supports an HDL (preferably Verilog).

Are these mutually exclusive desires? I am willing to tolerate an
expensive programmer.

DIP is the most constraining of these conditions,

The largest DIP CPLD I know of is the
Atmel ATF2500C (DIP40, Digikey $6.25+), which has 48 Macrocells (24
buried, 24 pins)
It has smaller siblings ATF750CL(20MC DIP24), and the ATF22V10 (10MC
DIP24), and even ATF16V8(8MC DIP20)

All of these need a Programmer, (eg EETools ChipMAX 2)

If you can tolerate PLCC, Digikey have ATF1508ASVL-20JU84

Simplest tool suite is Atmel-CUPL, very fast and works from a
TextEditor, which can also generate Test vectors. These append to the
JED file, and run in the programmer after device pgm.

Thus students can do functional sim, and also verify actual chip
operation, before they get to the breadboard.

hth

-jg

 

[glen herrmannsfeldt]

Tim Wescott <tim@seemywebsite.com> wrote:
(snip)

Just a thought:

I recently had a conversation with the son of a friend of mine. He was
taking a logic class, and had some questions about how to do things. He
remarked that this was his second class, and that the first ended up
being more about how to shoe-horn logic into teeny little devices rather
than learning the language.

Is that a quarter, semester, or year class?

Knowing how to shoe-horn logic into small spaces is an essential skill,
but I think it's something you want to impose on people _after_ you've
given them a chance to play in a _big_ sand box.

Is there something in between?

I do believe that students need to learn to think in terms of
logic, as distinct from (serial) software. Thinking about combining
gates and FF's to make working logic is a good starting point.
Seeing how inefficiently you can do it (in a large sand box)
doesn't seem to me to be the right direction. (It isn't good
in software, either.)

I believe also that logic minimization is still a little more
important than software optimization. Digital logic and FPGAs
are needed when something needs to be faster than it can be
done in software (such as on a microcontroller). In addition,
it is easier to start learning logic minimization on smaller
systems, and build up to larger ones.

-- glen

 

[glen herrmannsfeldt]

stephen.craven@gmail.com <stephen.craven@gmail.com> wrote:

I am teaching an intro digital logic lab. In past semesters I used the
final assignments to introduce students to structural Verilog netlists
using Spartan 3E boards.

As the class size has outgrown my Spartan boards and I feel that a
modern FPGA is overkill for the simple circuits they are building, I
am looking for a different solution and would appreciate your
suggestions.

(snip of constraints)

What I would like to see is a board designed around a smaller FPGA,
specifically for introductory classroom use. It used to be that
a digital clock was a favorite introductory project, though maybe
not any more. Still, a board with resources to do that wouldn't
be a bad start for an introductory class.

Some time ago, I thought about a board that could be used in
introductory classes for a digital clock (or something else with
LED display and simple inputs), and later classes to do
(what I believe is misnamed) SDR. (Software defined radio.)

That is, with a minimal amount of external hardware needed, such
that one could build the rest in the FPGA. (Antenna input,
RF amplifier, ADC, DAC, audio amplifier, speaker.)

If produced in large enough quanitities, it should be affordable
for each student to buy one, and that would allow for economy
of scale.

-- glen

 

[Hal Murray]

My goals:
(1) A cheap reprogrammable PLD / FPGA (~$10 or less),
(2) A DIP package suitable for use in a breadboard, and
(3) A simple tool suite that supports an HDL (preferably Verilog).

Are these mutually exclusive desires? I am willing to tolerate an
expensive programmer.

I can't quite figure out what you are trying to do.

If you are OK with an expensive programmer, I'd look for
boards that included a USB programmer. The interesting
stuff may be close to $10 over an expensive programmer.

That doesn't get you a DIP package.

--
These are my opinions, not necessarily my employer's. I hate spam.

 

[glen herrmannsfeldt]

Hal Murray <hal-usenet@ip-64-139-1-69.sjc.megapath.net> wrote:

My goals:
(1) A cheap reprogrammable PLD / FPGA (~$10 or less),
(2) A DIP package suitable for use in a breadboard, and
(3) A simple tool suite that supports an HDL (preferably Verilog).

Are these mutually exclusive desires? I am willing to tolerate an
expensive programmer.

I can't quite figure out what you are trying to do.

If you are OK with an expensive programmer, I'd look for
boards that included a USB programmer. The interesting
stuff may be close to $10 over an expensive programmer.

I thought the idea of expensive programmer was that only
one was needed, even for a large number of boards.
(Though that causes a bottleneck in the classroom.)

-- glen

 

[Nico Coesel]

"stephen.craven@gmail.com" <stephen.craven@gmail.com> wrote:

All,

I am teaching an intro digital logic lab. In past semesters I used the
final assignments to introduce students to structural Verilog netlists
using Spartan 3E boards.

As the class size has outgrown my Spartan boards and I feel that a
modern FPGA is overkill for the simple circuits they are building, I
am looking for a different solution and would appreciate your
suggestions.

My goals:
(1) A cheap reprogrammable PLD / FPGA (~$10 or less),
(2) A DIP package suitable for use in a breadboard, and
(3) A simple tool suite that supports an HDL (preferably Verilog).

Did you look into the X9500 series for Xilinx? They cost a few dollars
in single quantities. You can use a PLCC socket which is very
breadboard friendly. You can use Xilinx ISE tools and your favourite
HDL. Programming can be done using Xilinx's standard parallel or USB
cable.

--
Failure does not prove something is impossible, failure simply
indicates you are not using the right tools...
nico@nctdevpuntnl (punt=.)
--------------------------------------------------------------

 

[Andy]

Not _exactly_ like what you were asking for, but the Actel Igloo Nano
Starter kit, or the Igloo Icicle Evaluation board might get you going.
I don't know if Actel has educational discount programs.

Andy

 

[allsey87]

Can't believe no one has mentioned diligents CMOD yet!!

http://www.digilentinc.com/Products/Detail.cfm?NavPath=2,400,798&Prod=CMOD

cost is $17, supports VHDL and Verilog (use the free WebPack design
tool from xilinx, also comes with free simulator Isim) and has a
standard DIP header perfect for connecting to breadboards.

Although I believe an external clock is required, nothing a simple
ASIC like 555 timer (5c?) couldn't provide tho...

Cheers Mike.