FPGA

Archiver

Guys,

I know this is not the site for FPGA, but I don't know where else to
turn.

I would like a short introduction to what FPGA is. How does it
differ from PLD or PAL?

Is it suitable for combinatorial logic or sequential logic or both?

Which of the offerings by Parallax do you recommend for a FPGA
beginner whose basic goal is to learn and get some hands on
experience?

Can anyone give me an example of how to use an FPGA?

I think I "know" what it is, but I want to make sure before I buy one.


Thanks for help.

Archiver

Look at Al William's site -- excellent overview.

All "Programmable Logic" chips allow you to
implement a digital design of logic gates into
a chip. When you do this you get a device
which implements a state-machine, or a logic
equation -- and can run much faster than the
equivalent in a microprocessor.

An FPGA differs from PLD or PAL in that typically
in a PLD (like 22V10) you actually 'burn' fuses
in the device -- the device itself holds the
configuration.

An FPGA typically has a MUCH larger 'sea-of-gates'
to be connected. Some of the largest actually
download their configuration from an attached
EEPROM on power-up. Also, FPGA can be
re-programmed in-circuit. Most PLD or PAL
require a special programmer.

It is suitable for combinatorial logic. For
sequential logic, if you can design a
state-machine implementation, you can put that
into an FPGA.

A "typical" small example often used is to
build a traffic light control state-machine.
Inputs are the car-sensors in the pavement,
and a 'clock-tick'. Outputs are the Yellow-Red-
Green light signals in all 4 directions.

I've used them for communication capture.
Some have DSP cores, and can give you fast
fourier transforms in real-time (derive the
frequency components of an input signal).
Some FPGA's are big enough to implement your
own microprocessor core inside. Some give
you LOTS of I/O in a small package.

Parallax sells 3 development boards supporting
the Altera FPGA's. If your need for signal
processing speed is not met by the 50 MIPS
SX processor line, FPGA's give you a higher
speed alternative.

--- In basicstamps@yahoogroups.com, "basicstampede"
<basicstampede@y...> wrote:
> Guys,
>
> I know this is not the site for FPGA, but I don't know where else
to
> turn.
>
> I would like a short introduction to what FPGA is. How does it
> differ from PLD or PAL?
>
> Is it suitable for combinatorial logic or sequential logic or both?
>
> Which of the offerings by Parallax do you recommend for a FPGA
> beginner whose basic goal is to learn and get some hands on
> experience?
>
> Can anyone give me an example of how to use an FPGA?
>
> I think I "know" what it is, but I want to make sure before I buy
one.
>
>
> Thanks for help.