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I'm trying to get a broad view of embedded stuff.

I got a series of (what I hope are not) 12 silly questions which I'm
hoping to clear up.  Here goes :


1) Are FPGAs essentially scaled up microcontrollers?  That is they
differ from microcontrollers in that they have more programmable gates
and more memory space (?)

2) Why would someone use an FPGA over say a minil ATX form factor
motherboard with a Pentium chip?  What advantage does an FPGA offer
over a regular mini motherboard with a microchip?  

3) I keep calling it "mini motherboards with pentium chips".  What is
the proper term for it?  PC/104 boards ??

4) How do FPGA differ from ASICS.  I'm thinking FPGA are for more
general purpose whie ASICS are for more specific purposes.  

5) Is the method of programming an ASICS and FPGA radiacally different
or similar?

6) Will FPGAs eventually drop in price and replace microcontrollers
for many functions?  (assuming size is not important)

7) Is DSP (digital signal processing) done on FPGAs or some other type
of board?

8) Is embedded linux mostly loaded onto those mini boards with Pentium
chips?  

9) When people talk about embedded systems, are they mostly talking
about microcontrollers, FPGAs, ASICS or mini motherboards with pentium
chips?

10) Are mini motherboards often used in conjunction with custom
designed boards with microcontrollers?  e.g. the microcontroller board
collects data and feeds that back to the mini motherboard.  The mini
motherboard processes data spits that info out to another board with a
microcontroller which moves a stepper motor.

11) What kind of board are they using in my cable modem, DVD player,
LCD screen?  

12) Once I get comfortable with using a microcontroller, what would be
the next step in learning?  I'm thinking of learning more about using
embedded linux on those mini mobos with pentium chips.  

Last but not least, thank you for your time!

Re: Questions from newbie

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Absolutely not. They are logic gates that are field programmable.
 
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No idea, since an FPGA isn't a motherboard or a Pentium chip. E.g. how do
you add your new PCI card to a FPGA?

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PC/104 are a particular form factor. So is mini and microATX. What "it"
are you talking about?
 
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ASICs are more like regular ICs. You cannot reprogram them like FPGAs. The
two can be used interchangeably in many cases.
 
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Yes, FPGAs you download you program into them and ASIC are manufactured by
silicon fabrication houses.

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Since they are a general solution, I don't see how they could be cheaper
than a mass-produced, cost optimized CPU.
 
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Sure I suppose.

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I guess since those "mini" motherboards are just like regulare PC
motherboards for the most part.
 
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All of them but I typically think of it as microcontrollers. After all
there's Windows XP Embedded (I kid you not).
 
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I have no idea.
 
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Probably a full custom board (e.g. not a PC mother board).
 
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Get a Linux vendor supported evaluation boards.

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Re: Questions from newbie


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I can't seem to get my head around fpga's.  Do microcontrollers not
have logic gates in them?  Can't see what the difference is between
programming a microprocessor/microcontroller and programming an FPGA.


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It isn't a motherboard, and it isn't a chip.  ........my mind has gone
blank trying to figure out what they are :)

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So then they are just like microcontrollers aren't they.  You load a
program in and they do whatever the program wants them to do.

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Yes I'm aware.

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Would it have a chip in there and if so what kind?

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Copy that.

Thanks!

Re: Questions from newbie

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Go read some documents at www.xilinx.com.

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Yes but *you* cannot change what the gates in the MCU do. You can in an
FPGA. The MCU will always fetch programs and do with them what they are
hardcoded to do. FPGAs can be "programmed" to provide a 32-bit latch,
"reprogrammed" to provide a bus interface between other devices, or
provide coprocessor-like computations.

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No. With FPGAs you actually "change" the hardware connections inside the
FPGA. With an MCU you just change the instruction stream that the
poor-fixed-function MCU must blindly execute.

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Re: Questions from newbie

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BTW, what is the difference between FPGAs, CPLDs, GALs and PALs?

regards, Bernd

Re: Questions from newbie
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Some practical definitions.

PAL means Programmable Array Logic and contains typically <= 10 of cells
that can be programmed using fuse logic.
PLA are more flexible than PALs but also slower, not so common..
GALs (Generic Array Logic) are PALs designed in an EEPROM technology and
thus have reprogrammability
All the things above are PLDs    - Programmable Logic Devices.
PLDs typically have a large number of inputs to an AND-OR array.Often the
output cannot handle every combination
of input-output due to restrictions.

CPLDs means Complex Programmable Logic Devices and are GALs with more
registers/ - I/O.

FPGA = Field Programmable Gate Arrays.
They are normally SRAM based, and often have very few inputs, but the output
can use every combination of the inputs.

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Re: Questions from newbie
Are PLDs all obsolete now?  Or getting obsolete?

Are PLDs all superseeded by microcontrollers/mobos with
microchips/FPGA boards?



Re: Questions from newbie

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I think many of the early simple PLDs are obsolete, and have been
replaced with more versatile versions.
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No.  A PLD is just a bunch of logic gates and flip-flops that the user
can interconnect as needed.  It would replace a bunch of simple TTL
logic chips.  A microcontroller would not replace a PLD/PLA/PAL.

A PLD/PAL/PLA/FPGA might serve as "glue logic" around a
microcontroller or microprocessor.

The "programmable" in these device names may be a bit misleading - I
think a better term would be "configurable", and Altera uses that term
with their FPGA parts.

FPGAs are configured at power-up (or before, for the EPROM types), and
keep the same configuration all the time the system is operating.

A microcontroller or microprocessor continually reads and processes
program instructions in normal operations.
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Re: Questions from newbie

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He said it isn't "a Pentium chip". Pentium isn't the whole world you know,
in fact it's a very small percentage of the total CPU market.

An FPGA is a chip, in which you can reprogram the interconnections between
the logic gates. In a CPU you can load a program which performs logical
operations, but you can't change the actual interconnections between the
internal gates.

In the embedded Linux world, you'll find many X86 [i.e. pentium family]
systems, but there is a large amount of stuff done on ARM and PPC as well.

When you simply need something that a PC can do in an embedded package, you
might use an off the shelf X86 board[1], but when something special purpose
is needed and you're designing your own board, there's often no advantage in
sticking with X86, and processors more suited to embedded systems will have
considerable benefits.

For example a project I recently worked on needed an embedded Linux system
for which a new board was designed using the PPC 855T CPU. Because this chip
has on-board ethernet, UARTs and hardware HDLC the board design was much
simpler than if we'd used an X86 family chip.

[1] There is a wide range of ARM & PPC boards available too.

Re: Questions from newbie
Hello zalster,
    Let's get some acronyms down first:
            FPGA = Field Programmable Gate Array
            ASIC = Application Specific Integrated Circuit
     Judging from your questions, it wasn't obvious that you knew what these
acronyms meant.  FPGAs are reprogrammable logic devices that allow you to
place a chip on a board, then adjust the logic that the board performs by
designing new logic that gets loaded, usually at powerup, into the FPGA.
The programming for the FPGA logic usually resides in a seperate memory
device, usually a serial EEPROM.  I've never worked with ASICs, but I have
the impression that they are exclusively used in high-volume applications.

    FPGAs aren't microcontrollers.  Microcontrollers execute a program and
usually an FPGA is placed between a microcontroller and peripheral devices
like RAM, EEPROM, or other devices like MPEG encoders.  Microcontrollers
have internal RAM, ROM, clock generators, and lots of registers that work in
a certain, pre-ordained fashion.  FPGAs might have some of these components,
but not usually.  Although there are some FPGAs that will allow you to load,
for example, an 8051 core into them and then they look like an 8051
microcontroller.  Is this confusing enough for you?

   PC/104 is a form factor, an industry standard board size, something like
3" x 3" with standardized pinouts on their interfacing connectors.  Some
have Pentium processors, some have Power PC, or different processors.  There
are lots of PC/104 boards that don't have processors, but perform some other
functions like digital or analog I/O, multiple RS-232 interfaces, LCD
interfaces, and others.  You can control PC/104 boards with embedded Linux
or other operating systems like DOS, QNX, Nucleus, or others.  PC/104 boards
are usually used in industrial or military applications, so these boards are
usually more pricy than other standardized form factors, but they can take
more abuse from temperature variations, humidity, vibration, and other
factors.

   Most likely the boards in your cable modem and other consumer electronics
are totally non-standard form factors.  Open them up and take a look, just
turn the power off beforehand.

    If you are interested in learning about microcontrollers, I'd purchase
an evaluation kit and test it out.  I would start with an 8-bit or 16-bit
architecture to keep things simpler.  Believe me, an 8-bit microcontroller
will keep you busy for a long time.  Evaluation kits from Zilog or Phytec
will cost you from $50 to $170.







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Re: Questions from newbie

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woah woah woah! slow down kid  :)  

Between a microcontroller and peripheral devices?  What could possibly
be going on between a microcontroller an peripheral device?  ]

What would you say are FPGA's used for?  I mean could you give me an
example of when a peron might consider using an FPGA.    

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Very much thank you :)

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Ah I see.  Power PCs.. aren't those macintosh chips?  How is it mac
gets to be so popular?  In desktop terms at least, PCs control almost
all of the market.


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never knew a board could run without a processor...

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Copy that.  QNX and stuff are for real time isn't it?

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Though i wanted to start with AVR microcontrollers, some PIC fanatics
influenced me into starting with Pics.  I hope i made the right choice
though looking at the message below of a newbie praising AVRs, my
heart sinks a little.  I have already ordered the PIC programmer.
Avrfreaks sure looks like a great place for newbies.


Re: Questions from newbie

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and
devices

Here's an example:  You have a microcontroller with 32 address and 32 data
lines, but various Chip Selects, and you also have an audio encoder chip
with address/data lines, plus output enable, chip select, etc. lines.  You
will need some type of handshaking logic between the two devices in order to
transfer data between them.  You put the FPGA between the two devices and
now you have an intermediary device that can flexibly be programmed to set
up and maintain logic between the two devices.  Now you can digitize your
voice into an internet phone or whatever application you wanted.



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like

Don't be deceived into thinking that PCs are the biggest market.  The
biggest market for microcontrollers is in the 4, 8, and 16-bit
microcontrollers that go into automobiles, tools, consumer electronics.  PCs
and 32-bit microprocessors are something like 8% of the overall market.
Most video game modules have more processing capability than the average
desktop PC, plus they usually have 2,3, or 4 micros where a desktop PC has
1.



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boards
are
take

Yes, real time is another topic for another day.


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purchase
microcontroller

I've never worked with AVRs or PICs.  I know that there are a lot of
hobbyists that use them, but my OJT was with Intel 8051 microcontrollers.  I
like to have different sources and there are a lot of derivatives of the
8051 uC out there now.



Re: Questions from newbie
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PC/104 is a form factor. It's like saying PCI or ISA. What he means is that
there are lots of PC/104 cards with I/O devices on them that you can attach to
a PC/104 CPU card.



Re: Questions from newbie
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You have a lot to learn...

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No... they are mainly used in high end comms.... most of the telephone
and internet runs on them.

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Because they work.... MACs tend to have them majority of the
professional graphics, film and music markets.

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Any ISC or PCI card?


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This is comp.arch.embedded....


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AVR, PIC or 8051 are OK for beginners because they are inexpensive and
there is a lot of information about for them.



Let's start again..


1 what is your background?

2 What to you want to do?

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Re: Questions from newbie

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Internet routers would be MIPS, not PowerPC right?

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Re: Questions from newbie
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The SDH stuiff I worked on for two of the worlds major comms compaines
used PPC.

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Re: Questions from newbie

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You did not. JTAG programmable and debuggable 8051's from Cygnal or
MSP430's from Texas Instruments would have made your life much easier.

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Re: Questions from newbie
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Actually any of the 8051's would be a good idea.


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Re: Questions from newbie

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I agree, of course. I just love JTAG debug.

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Re: Questions from newbie

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An FPGA ic an IC containing a large number of logic gates and
flip-flops that the user can "wire up" as required for his
application.  An FPGA can be used to replace a number of "normal"
logic chips, greatly reducing the PC Board space required to perform a
particular task.

An FPGA may be programmed by drawing schematic diagrams, just as you
would design a circuit with normal TTL logic chips.

An ASIC (Application Specific Integrated Circuit) may start out as an
FPGA.  Once the equipment manufacturer decides he has the design
correct, and will need a large number of identical parts, he may
convert the FPGA design to ASIC, as the ASIC part will be much cheaper
than the FPGA in large quantities.

Just to confuse you further, some large FPGAs can be "programmed" to
emulate a processor.

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As I understand it, to make a working PC/104 system you would stack
several PC/104 boards together - one would have the processor, others
would have I/O devices of various sorts.


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