Will FPGAs suit my need?

Hi all,

I'm an electronics hobbyist; my projects are generally quite small.
They generally consist of me using 7400 chips, and in some cases the
PIC microcontroller. However, I'm wanting to stretch out a little. What
I'm after is nothing more than a chip that contains thousands of 7400
chips, no clock, no onboard memory etc... Just a microchip which is in
essence thousands of 7400 chips. I would like actual control of the
connections between the chips, so I can say what gates link with what
without me doing something so general as 1+1 and the programmer
figuring out what to put.

I thought FPGAs might be suitable, but they all appear to try to offer
more than just something like that. Can anybody point me in some rough
direction?

Thanks for your time,
Nick

<NickHolby@googlemail.com> wrote in message 
news:1168700683.831757.179720@l53g2000cwa.googlegroups.com...
> Hi all,
>
> I'm an electronics hobbyist; my projects are generally quite small.
> They generally consist of me using 7400 chips, and in some cases the
> PIC microcontroller. However, I'm wanting to stretch out a little. What
> I'm after is nothing more than a chip that contains thousands of 7400
> chips, no clock, no onboard memory etc... Just a microchip which is in
> essence thousands of 7400 chips. I would like actual control of the
> connections between the chips, so I can say what gates link with what
> without me doing something so general as 1+1 and the programmer
> figuring out what to put.
>
> I thought FPGAs might be suitable, but they all appear to try to offer
> more than just something like that. Can anybody point me in some rough
> direction?
>
> Thanks for your time,
> Nick
>

You will be better off starting out with a CPLD.
These are stand alone devices that do not require an external configuration 
memory and are generally much cheaper than FPGA's, typically under $5.

Have a look at
http://www.altera.com/products/devices/cpld/max2/mx2-index.jsp

Download Alteras' free software and start experimenting!
Altera software supports schematic entry and the included libraries include 
most of the 7400 series to get you started.
https://www.altera.com/support/software/download/altera_design/quartus_we/dnl-quartus_we.jsp

Good luck!

Icky 

http://www.digilentinc.com/

Austin

On 13 Jan 2007 07:04:45 -0800, NickHolby@googlemail.com wrote:

>Hi all,
>
>I'm an electronics hobbyist; my projects are generally quite small.
>They generally consist of me using 7400 chips, and in some cases the
>PIC microcontroller. However, I'm wanting to stretch out a little. What
>I'm after is nothing more than a chip that contains thousands of 7400
>chips, no clock, no onboard memory etc... Just a microchip which is in
>essence thousands of 7400 chips. I would like actual control of the
>connections between the chips, so I can say what gates link with what
>without me doing something so general as 1+1 and the programmer
>figuring out what to put.
>
>I thought FPGAs might be suitable, but they all appear to try to offer
>more than just something like that. Can anybody point me in some rough
>direction?
>
>Thanks for your time,
>Nick


FPGA. Get one of the Xilinx development boards and download the
WebPack free software. Expect a decently nasty learning curve, but
then you'll be able to do amazing stuff. Need a dozen 32-bit up/down
counters? Twenty 16x16 multipliers? No sweat.

John

On 2007-01-13, NickHolby@googlemail.com <NickHolby@googlemail.com> wrote:
> Just a microchip which is in
> essence thousands of 7400 chips. I would like actual control of the
> connections between the chips, so I can say what gates link with what
> without me doing something so general as 1+1 and the programmer
> figuring out what to put.

The Xilinx WebPack includes a schematic capture input that allows you to
use 7400 chips to represent your logic.  You can play with it without
buying any hardware.

As for hardware, a CPLD is tens to hundreds (in a few cases thousands)
of flops which can be connected with quite a bit (equivalent of hundreds
or thousands of 7400 series chips) of combinatoral logic.  They're
generally flash programmable and available in human-solderable packages.

An FPGA is thousands to tens or hundreds of thousands of flops and
connecting logic.  They require some kind of external programming (like
a flash eeprom) and the larger parts are only available in fine pitch
or BGA type packages.

-- 
Ben Jackson AD7GD
<ben@ben.com>
http://www.ben.com/

NickHo...@googlemail.com wrote:
> Hi all,
>
> I'm an electronics hobbyist; my projects are generally quite small.
> They generally consist of me using 7400 chips, and in some cases the
> PIC microcontroller. However, I'm wanting to stretch out a little. What
> I'm after is nothing more than a chip that contains thousands of 7400
> chips, no clock, no onboard memory etc... Just a microchip which is in
> essence thousands of 7400 chips. I would like actual control of the
> connections between the chips, so I can say what gates link with what
> without me doing something so general as 1+1 and the programmer
> figuring out what to put.
>
> I thought FPGAs might be suitable, but they all appear to try to offer
> more than just something like that. Can anybody point me in some rough
> direction?
>
> Thanks for your time,
> Nick

FPGAs will do this, as will CPLDs as others have suggested.
There are also FLASH FPGAs, and  CPLDs wih FPGA fabric, like
MaxII and MachXO, so there are plenty of HW choices.

Your real challenge is deciding just how you are most comfortable
doing this bit:  "I would like actual control of the connections
between the chips"
- entry schemes range from Schematic, to Boolean Eqn
(Abel/CUPL/WinPLACE)s, to HDLs like
Verilog orVHDL.

Some CPLD vendors are Actel, Altera, Atmel, ICT(anachip), Cypress,
Lattice, Xilinx

What is your supply voltage range ? - that will filter significantly
the PLD candidates

-jg

Thanks alot for your responses they've been quite helpful! It seems
FPGAs or CLPDs are the way forward.

Much appreciated! :-)
Nick

Ben Jackson <ben@ben.com> wrote:

>On 2007-01-13, NickHolby@googlemail.com <NickHolby@googlemail.com> wrote:
>> Just a microchip which is in
>> essence thousands of 7400 chips. I would like actual control of the
>> connections between the chips, so I can say what gates link with what
>> without me doing something so general as 1+1 and the programmer
>> figuring out what to put.
>
>The Xilinx WebPack includes a schematic capture input that allows you to
>use 7400 chips to represent your logic.  You can play with it without
>buying any hardware.

This is a dangerous advice. 7400 logic is often used in an
asynchronous way. Building a flip-flip out of NOR/NAND gates will work
with 7400 series logic, but in an FPGA it most probably won't.

-- 
Reply to nico@nctdevpuntnl (punt=.)
Bedrijven en winkels vindt U op www.adresboekje.nl

Nico Coesel wrote:
> This is a dangerous advice. 7400 logic is often used in an
> asynchronous way. Building a flip-flip out of NOR/NAND gates will work
> with 7400 series logic, but in an FPGA it most probably won't.
>
> --
> Reply to nico@nctdevpuntnl (punt=.)
> Bedrijven en winkels vindt U op www.adresboekje.nl

Does that still stand with CPLDs?

Nick

<NickHolby@googlemail.com> wrote in message 
news:1168783597.143713.98180@v45g2000cwv.googlegroups.com...
> Nico Coesel wrote:
>> This is a dangerous advice. 7400 logic is often used in an
>> asynchronous way. Building a flip-flip out of NOR/NAND gates will work
>> with 7400 series logic, but in an FPGA it most probably won't.
>>
>> --
>> Reply to nico@nctdevpuntnl (punt=.)
>> Bedrijven en winkels vindt U op www.adresboekje.nl
>
> Does that still stand with CPLDs?
>
> Nick
>

Yes it could, dependent on construction and how the synthesis is forced - 
but then you would use a 7474 - wouldn't you?

Cross coupled nand set-resets work fine for both Altera FPGA and CPLD's.

Icky