Beginer's FPGA with SERDES

[rickman]

Some hams want to work with FPGAs to generate high speed PN sequences in the
GHz range. LFSR designs are about as simple as you can get in an FPGA. The
only trick is getting the resulting signal out of the FPGA. Rather than
outputting a parallel word at some 100's of MHz into a shift register
clocked in the GHz range, it seems easier to use a SERDES to shift it out
directly from the FPGA.

But not all FPGAs have SERDES. Which are the lowest cost devices and the
easiest to use? By "easiest" I mean board level with a built in programming
interface so they just connect a USB cable and maybe power supply, no dongle
needed.

All the FPGAs I've worked with lately (by that I mean over the last 10
years) didn't include a SERDES.

--

Rick C

Viewed the eclipse at Wintercrest Farms,
on the centerline of totality since 1998

 

[Theo Markettos]

rickman <gnuarm@gmail.com> wrote:

But not all FPGAs have SERDES. Which are the lowest cost devices and the
easiest to use? By "easiest" I mean board level with a built in
programming interface so they just connect a USB cable and maybe power
supply, no dongle needed.

In Intel-land, the Cyclone IV GX and Cyclone V GX are the cheap transceiver
devices - or the SX version if you also want an ARM core.

There are boards like:
http://www.terasic.com.tw/cgi-bin/page/archive.pl?Language=English&CategoryNo=139&No=746
http://www.terasic.com.tw/cgi-bin/page/archive.pl?Language=English&CategoryNo=167&No=830
and with an ARM:
http://www.terasic.com.tw/cgi-bin/page/archive.pl?Language=English&CategoryNo=167&No=816

I think the Lattice ECP5 also has transceiver support, though I haven't used
it. For instance:
http://www.latticesemi.com/Products/FPGAandCPLD/ECP5ECP5GPromotion.aspx

(one thing to watch is any additional licences that may be needed)

The other question is: what do you want to connect it to?
It's a GHz frequency signal, so you'll need to take care of signal integrity
to get it anywhere. Therefore the connector format you intend to use may be
important.

Theo

 

[rickman]

Theo Markettos wrote on 10/21/2017 3:19 PM:

rickman <gnuarm@gmail.com> wrote:
But not all FPGAs have SERDES. Which are the lowest cost devices and the
easiest to use? By "easiest" I mean board level with a built in
programming interface so they just connect a USB cable and maybe power
supply, no dongle needed.

In Intel-land, the Cyclone IV GX and Cyclone V GX are the cheap transceiver
devices - or the SX version if you also want an ARM core.

There are boards like:
http://www.terasic.com.tw/cgi-bin/page/archive.pl?Language=English&CategoryNo=139&No=746
http://www.terasic.com.tw/cgi-bin/page/archive.pl?Language=English&CategoryNo=167&No=830
and with an ARM:
http://www.terasic.com.tw/cgi-bin/page/archive.pl?Language=English&CategoryNo=167&No=816

I think the Lattice ECP5 also has transceiver support, though I haven't used
it. For instance:
http://www.latticesemi.com/Products/FPGAandCPLD/ECP5ECP5GPromotion.aspx

(one thing to watch is any additional licences that may be needed)

The other question is: what do you want to connect it to?
It's a GHz frequency signal, so you'll need to take care of signal integrity
to get it anywhere. Therefore the connector format you intend to use may be
important.

The ham is using it as an analog signal, so he won't be caring about
harmonics. It is a noise source for test gear, uniform over a wide
bandwidth. I assume a ham can handle the analog aspects of the signal, lol.

Too bad that promo on the ECP5 board expired. I dug around a little and
didn't find a SERDES on any of the Flash based parts by Lattice. I don't
see any Altera boards with SERDES under $100. I guess if they are using the
chip with the SERDES they figure you are going to use it with PCIe or
similar, so the cost goes up.

--

Rick C

Viewed the eclipse at Wintercrest Farms,
on the centerline of totality since 1998

 

[rickman]

Theo Markettos wrote on 10/21/2017 3:19 PM:

rickman <gnuarm@gmail.com> wrote:
But not all FPGAs have SERDES. Which are the lowest cost devices and the
easiest to use? By "easiest" I mean board level with a built in
programming interface so they just connect a USB cable and maybe power
supply, no dongle needed.

In Intel-land, the Cyclone IV GX and Cyclone V GX are the cheap transceiver
devices - or the SX version if you also want an ARM core.

There are boards like:
http://www.terasic.com.tw/cgi-bin/page/archive.pl?Language=English&CategoryNo=139&No=746
http://www.terasic.com.tw/cgi-bin/page/archive.pl?Language=English&CategoryNo=167&No=830
and with an ARM:
http://www.terasic.com.tw/cgi-bin/page/archive.pl?Language=English&CategoryNo=167&No=816

I think the Lattice ECP5 also has transceiver support, though I haven't used
it. For instance:
http://www.latticesemi.com/Products/FPGAandCPLD/ECP5ECP5GPromotion.aspx

(one thing to watch is any additional licences that may be needed)

The other question is: what do you want to connect it to?
It's a GHz frequency signal, so you'll need to take care of signal integrity
to get it anywhere. Therefore the connector format you intend to use may be
important.

While trying to dig through the Altera/Intel datasheets it seems they don't
have the same sort of documents they used to have. Everything is broken up
into many smaller manuals and most don't even have lead in information like
a table of contents or intro page, it just starts with data! Is this an
Intel thing?

--

Rick C

Viewed the eclipse at Wintercrest Farms,
on the centerline of totality since 1998

 

[Theo Markettos]

rickman <gnuarm@gmail.com> wrote:

While trying to dig through the Altera/Intel datasheets it seems they don't
have the same sort of documents they used to have. Everything is broken up
into many smaller manuals and most don't even have lead in information like
a table of contents or intro page, it just starts with data! Is this an
Intel thing?

No, the Altera site is pretty much the same as before the rebrand.
They do two versions of documentation: one is the whole manual for the chip,
sometimes split into a couple of volumes (eg vol1 internals, vol2
transceivers). Then the individual chapters are also available separately.
When googling, the individual bits tend to rank higher - but when you want
the whole document to read it's useful to know you can go to the device page
and get the full PDF. Also worth bearing in mind there's lots of sharing -
lots of features are the same across families, so no point duplicating info.

My point about connectors is that often transceivers come off on FMC or HSMC
connectors - can your ham deal with those? You'll need a PCB, probably a 4
layer one if you're going more than a few mm.

Theo

 

[rickman]

Theo Markettos wrote on 10/21/2017 6:24 PM:

rickman <gnuarm@gmail.com> wrote:
While trying to dig through the Altera/Intel datasheets it seems they don't
have the same sort of documents they used to have. Everything is broken up
into many smaller manuals and most don't even have lead in information like
a table of contents or intro page, it just starts with data! Is this an
Intel thing?

No, the Altera site is pretty much the same as before the rebrand.
They do two versions of documentation: one is the whole manual for the chip,
sometimes split into a couple of volumes (eg vol1 internals, vol2
transceivers). Then the individual chapters are also available separately.
When googling, the individual bits tend to rank higher - but when you want
the whole document to read it's useful to know you can go to the device page
and get the full PDF. Also worth bearing in mind there's lots of sharing -
lots of features are the same across families, so no point duplicating info.

I wasn't able to find the usual info that is easily available on other
makers' sites. They typically have a basic family manual that starts with
the overview and a summary of the devices in the family and the available
packages. This is followed by a high level description of the various
aspects of the workings of the chip and finally electrical and mechanical
data. Usually the fine points are covered in other manuals or tech notes.
When I typed in "cyclone V datasheet" I got some hundreds of hits ranked by
I assume relevance. Electrical specs came up first. I never found what I
was looking for. I had to rely on the brief info on the web pages.

My point about connectors is that often transceivers come off on FMC or HSMC
connectors - can your ham deal with those? You'll need a PCB, probably a 4
layer one if you're going more than a few mm.

Yeah, the guy seems to be thinking of putting a 20 pin device on his own
circuit board. I found a $30 Lattice FPGA board without SERDES for him, and
they also have some parts in QFN and there's always the ever present 144 pin
QFP. But he is talking about using ECL now. Whatever. Horse - water...

--

Rick C

Viewed the eclipse at Wintercrest Farms,
on the centerline of totality since 1998

 

[Theo Markettos]

rickman <gnuarm@gmail.com> wrote:

I wasn't able to find the usual info that is easily available on other
makers' sites. They typically have a basic family manual that starts with
the overview and a summary of the devices in the family and the available
packages. This is followed by a high level description of the various
aspects of the workings of the chip and finally electrical and mechanical
data. Usually the fine points are covered in other manuals or tech notes.
When I typed in "cyclone V datasheet" I got some hundreds of hits ranked by
I assume relevance. Electrical specs came up first. I never found what I
was looking for. I had to rely on the brief info on the web pages.

The starting point for Cyclone V docs is here:
https://www.altera.com/products/fpga/cyclone-series/cyclone-v/support.html
That seems to have what you suggest, just split over several manuals.

Yeah, the guy seems to be thinking of putting a 20 pin device on his own
circuit board. I found a $30 Lattice FPGA board without SERDES for him,
and they also have some parts in QFN and there's always the ever present
144 pin QFP. But he is talking about using ECL now. Whatever. Horse -
water...

I haven't seen a device with transceivers that wasn't a BGA, so you might be
in for trouble...

One option beyond the dev board is systems-on-module, where the FPGA is on a
carrier board and all signals are pinned out to connectors. That converts
the problem into interfacing with an FMC or similar connector. It isn't
impossible to do that with careful design on a 2 layer PCB (and the cheap
devices are max 3Gbps which isn't that fast), but do understand it won't be
a case of just plugging in.

Theo

 

[Evgeny Filatov]

On 22.10.2017 0:04, rickman wrote:

Theo Markettos wrote on 10/21/2017 3:19 PM:
rickman <gnuarm@gmail.com> wrote:
But not all FPGAs have SERDES. Which are the lowest cost devices and
the
easiest to use? By "easiest" I mean board level with a built in
programming interface so they just connect a USB cable and maybe power
supply, no dongle needed.

In Intel-land, the Cyclone IV GX and Cyclone V GX are the cheap
transceiver
devices - or the SX version if you also want an ARM core.

There are boards like:
http://www.terasic.com.tw/cgi-bin/page/archive.pl?Language=English&CategoryNo=139&No=746

http://www.terasic.com.tw/cgi-bin/page/archive.pl?Language=English&CategoryNo=167&No=830

and with an ARM:
http://www.terasic.com.tw/cgi-bin/page/archive.pl?Language=English&CategoryNo=167&No=816


I think the Lattice ECP5 also has transceiver support, though I
haven't used
it. For instance:
http://www.latticesemi.com/Products/FPGAandCPLD/ECP5ECP5GPromotion.aspx

(one thing to watch is any additional licences that may be needed)

The other question is: what do you want to connect it to?
It's a GHz frequency signal, so you'll need to take care of signal
integrity
to get it anywhere. Therefore the connector format you intend to use
may be
important.

The ham is using it as an analog signal, so he won't be caring about
harmonics. It is a noise source for test gear, uniform over a wide
bandwidth. I assume a ham can handle the analog aspects of the signal,
lol.

Besides, it's an interesting type of a DSP problem. A case for which an
m-sequence transform at the receiver side is an efficient solution.

Gene

 

[rickman]

Evgeny Filatov wrote on 10/22/2017 6:02 AM:

Besides, it's an interesting type of a DSP problem. A case for which an
m-sequence transform at the receiver side is an efficient solution.

I'm not sure what you are describing.

I remember learning about a photoacoustic spectrometer my professor was
working on. It used a disk with slots to shutter the optical beam from a
monochromator and self interfered by the disk making noise and vibrations.
I wondered if that could be mitigated by making the slots in the disk
different widths and detecting the acoustic signal in a synchronized manner.
I wasn't schooled in electronics yet and didn't realize that is the basis
of DSP techniques.

Is that the sort of thing you are talking about?

--

Rick C

Viewed the eclipse at Wintercrest Farms,
on the centerline of totality since 1998

 

[rickman]

Theo Markettos wrote on 10/22/2017 5:55 AM:

rickman <gnuarm@gmail.com> wrote:
I wasn't able to find the usual info that is easily available on other
makers' sites. They typically have a basic family manual that starts with
the overview and a summary of the devices in the family and the available
packages. This is followed by a high level description of the various
aspects of the workings of the chip and finally electrical and mechanical
data. Usually the fine points are covered in other manuals or tech notes.
When I typed in "cyclone V datasheet" I got some hundreds of hits ranked by
I assume relevance. Electrical specs came up first. I never found what I
was looking for. I had to rely on the brief info on the web pages.

The starting point for Cyclone V docs is here:
https://www.altera.com/products/fpga/cyclone-series/cyclone-v/support.html
That seems to have what you suggest, just split over several manuals.

Yeah, the guy seems to be thinking of putting a 20 pin device on his own
circuit board. I found a $30 Lattice FPGA board without SERDES for him,
and they also have some parts in QFN and there's always the ever present
144 pin QFP. But he is talking about using ECL now. Whatever. Horse -
water...

I haven't seen a device with transceivers that wasn't a BGA, so you might be
in for trouble...

One option beyond the dev board is systems-on-module, where the FPGA is on a
carrier board and all signals are pinned out to connectors. That converts
the problem into interfacing with an FMC or similar connector. It isn't
impossible to do that with careful design on a 2 layer PCB (and the cheap
devices are max 3Gbps which isn't that fast), but do understand it won't be
a case of just plugging in.

I don't believe he was serious about using an FPGA. He seems to be just
talking about things and not so interested in anything that he can't build
himself.

--

Rick C

Viewed the eclipse at Wintercrest Farms,
on the centerline of totality since 1998

 

[Evgeny Filatov]

On 23.10.2017 2:00, rickman wrote:

Evgeny Filatov wrote on 10/22/2017 6:02 AM:

Besides, it's an interesting type of a DSP problem. A case for which an
m-sequence transform at the receiver side is an efficient solution.

I'm not sure what you are describing.

I remember learning about a photoacoustic spectrometer my professor was
working on. It used a disk with slots to shutter the optical beam from
a monochromator and self interfered by the disk making noise and
vibrations. I wondered if that could be mitigated by making the slots in
the disk different widths and detecting the acoustic signal in a
synchronized manner. I wasn't schooled in electronics yet and didn't
realize that is the basis of DSP techniques.

Is that the sort of thing you are talking about?

Not really. The type of setup you described can be used to measure
impulse response of a system:

http://www.commsp.ee.ic.ac.uk/~mrt102/projects/mls/MLS%20Theory.pdf

Perhaps it's not what the ham is trying to achieve. Thought it's worth
mentioning, though.

Gene