5:42 p.m.
Hi,
I want to get an FPGA board to use for lowrisc and I'm considering getting
a Nexys Video rather than an Nexys 4 DDR, partly for future proofing, since
I saw somewhere that untethered lowrisc already uses ~70% of the LUTs of
the Nexys 4 DDR. Would I be making it much harder for myself to get it
running if I go with a Nexys Video? Are there any other drawbacks?
Regards,
Per
5:45 p.m.
Hi Per,
We also use the Nexys Video board and have had lowRISC running
successfully on it. I've cc'd Jonathan and Wei who will be able to
outline the important hardware differences.
best,
- Robert.
On 28 August 2016 at 09:42, Per Fransson <per.fransson.ml(a)gmail.com> wrote:
Hi,
I want to get an FPGA board to use for lowrisc and I'm considering getting
a Nexys Video rather than an Nexys 4 DDR, partly for future proofing, since
I saw somewhere that untethered lowrisc already uses ~70% of the LUTs of
the Nexys 4 DDR. Would I be making it much harder for myself to get it
running if I go with a Nexys Video? Are there any other drawbacks?
Regards,
Per
8:14 p.m.
Hello Per,
Just in case if Jonathan has not replied this email.
Internally we begin to use the Nexys Video board. Jonathan has
successfully booted a RISC-V Linux using the standalone configuration.
However, currently there are several issues:
The trace debugger does not work. The host computer cannot set up a UART
connection with the trace UART emulator.
Also the recently added execution in place (XIP) flash does not work
properly.
If you do not need to use the trace debugger or the XIP flash, the Nexys
Video board is already ready for use.
The noticeable difference between Nexys Video and Nexys4 DDR is that the
UART on the Nexys Video has no hardware flow control.
For the Nexys4 DDR board, we can currently run trace debugger with a
12Mb/s UART connection, which potential can only reach to 3Mb/s on the
Nexys Video board.
To try the Nexys Video board, you can clone
https://github.com/lowrisc/lowrisc-chip.git branch dev
Then the support for Nexys Video board is located at fpga/board/nexys4_video
The Nexys Video board is not mentioned in our tutorial yet due to the
remaining issues but all instructions should run OK with minimal
revision related to the different fpga directory.
Best regards,
Wei
On 28/08/2016 09:45, Robert Mullins wrote:
Hi Per,
We also use the Nexys Video board and have had lowRISC running
successfully on it. I've cc'd Jonathan and Wei who will be able to
outline the important hardware differences.
best,
- Robert.
On 28 August 2016 at 09:42, Per Fransson <per.fransson.ml(a)gmail.com> wrote:
> Hi,
>
> I want to get an FPGA board to use for lowrisc and I'm considering getting
> a Nexys Video rather than an Nexys 4 DDR, partly for future proofing, since
> I saw somewhere that untethered lowrisc already uses ~70% of the LUTs of
> the Nexys 4 DDR. Would I be making it much harder for myself to get it
> running if I go with a Nexys Video? Are there any other drawbacks?
>
> Regards,
> Per
8:43 p.m.
On 31.08.2016 13:14, Wei Song wrote:
For the Nexys4 DDR board, we can currently run trace debugger with a
12Mb/s UART connection, which potential can only reach to 3Mb/s on the
Nexys Video board.
Its actually 9.6 Mb/s (12 MBaud with 8-1 scheme), but we will soon also
support software (XON/XOFF) flow control:
https://github.com/TUM-LIS/glip/issues/28
This should also allow for 12 MBaud on boards without RTS/CTS flow control.
Cheers,
Stefan
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3 comments
4 participants
participants (4)
-
Per Fransson -
Robert Mullins -
Stefan Wallentowitz -
Wei Song