Hi Daniel!
(back to mailing list)
On 16.06.2017 06:04, Daniel Follesø wrote:
I have been doing some digging on the Nexys Video board, and have 3
separate plans that should make the board capable of fast communication
with the Host PC.
Awesome. Are you aware that we use a side project of mine for host
communication?
http://glip.io.
1) DPTI/ DSPI via prog port. See the Nexys Video reference manual for
a
quick overview( I can send you lots of links for docs and demo projects
from Digilent if you think this might be sufficient). I have done some
initial loop-back tests reaching 5 MB/s using DPTI. Requires drivers
from FTDI or libFTDI.
Cool, didn't have a look at this so far, but it is always preferable to
use something on-board.
2) Simple Ethernet link with host. Here is an example I would like
to
try out and maybe try to rewrite in SV/ Verilog:
*https://github.com/hamsternz/FPGA_GigabitTx*
A more long term solution might be to do something like
this:*https://github.com/hamsternz/FPGA_Webserver*
Excellent, I have also considered this and discussed with Wei and
Jonathan. The problem is more on the MAC side actually, there are plenty
of them available, but I couldn't figure out which one always works. The
Xilinx MAC is quite costy unfortunately..
Maybe it is worth creating a small Github repo to collect an overview of
open source ethernet cores and on which FPGAs they have been tested.
3) Use the FMC connector on the board with an FMC to USB 3 board
like
one of these( I think this might be the best long term solution):
*https://www.digikey.com/catalog/en/partgroup/ft600-and-ft601-evaluation-boards/55950*
*http://www.cypress.com/documentation/development-kitsboards/cyusb3acc-005-fmc-interconnect-board-ez-usb-fx3-superspeed
*
+
*http://www.cypress.com/documentation/development-kitsboards/cyusb3kit-003-ez-usb-fx3-superspeed-explorer-kit*
This is what we actually already did :) The FX3 is now part of the GLIP
project and Wei and I have experimented before with it on the KC705
board. Unfortunately, the trace lengths are messed up and we had issues
reaching the limit of 200 MBit/s, but it looks better on the VCU108,
that Max and Philipp at TUM develop on.
Apparently, not a hobbyist board. As I don't have a Nexys4 Video I was
not able to test it so far. I should get one..
I also have an FT600 evaluation board here, but never got at it, because
it only has the proprietary driver from FTDI. Also, I don't understand
why they didn't spent some logic on a single GPIO pin. GLIP standardizes
a FIFO interface plus a reset GPIO pin to better allow remote setups.
This reset pin is quite handy, and the FX3 is overall just the more
elegant (yet more costy) choice.
The Nexys Video have good student pricing and in my mind a good
alternative for the lowRISC project.
Yes, the academic pricing is great and it has plenty of user I/O. I
still don't own one, but will get one the next weeks I think. Do you
already have one?
Regarding alternatives with an Artix-7 200T FPGA, what do you think
of
the ZTEX "USB-FPGA Module 2.18b"?
*https://shop.ztex.de/product_info.php?cPath=25&products_id=99*
I love the ZTEX boards. At university we have used them for ages. They
just work and the FX3+Artix 200 is just a charme (despite its price).
For my other project (
optimsoc.org) it is the natural candidate, because
it really focuses on the manycore system-on-chip and I/O is not a
critical issue (can be emulated if needed). Anyways, for lowRISC the
ZTEX was also in discussion, but the I/O (and price) made the Nexys 4
DDR the more sensible choice.
GLIP should work out of the box on the ZTEX board. I will probably order
one soon and just test it out.
In the same class the micro modules (4x5 cm) from Trenz Electronics are
also quite neat, but I don't find a USB3 base board.
Cheers,
Stefan