[lowrisc-dev] lowrisc 0.5 release on custom Virtex 7 2000T

Dr Jonathan Kimmitt jrrk2 at cam.ac.uk
Mon Jan 29 10:02:34 GMT 2018


The clocks (on NexysDDR) are:

100MHz - incoming crystal oscillator

200MHz - mig_sys_clk to DDR controller (divided down to 25MHz for 
processor clk output)

60MHz - clk_io_uart to UART (divided down to 12MHz for trace debugger 
interface)

120MHz - clk_pixel to VGA monitor

50MHz (clk_rmii, clk_rmii_quad quadrature clocks) to Ethernet RMII

The mig_ui_clk is 50MHz corresponding to the 2:1 clock converter for AXI 
DDR memory.

On a different board you may well be able to go faster but these are the 
settings that we know work on the Artix-7.

Regards,

Jonathan


On 29/01/18 09:21, Anup Kini wrote:
> Hi All,
>
> I have gone through the code and need some clarification regarding the 
> clocks so that I can configure the mig correctly.
>
> - riscv processor clock - 50 MHz - from mig additonal clock - Is this 
> correct ?
> - mig - ui_clk - this returns 200 MHz, is this correct ?
> - uart16550 - is this clocked at 200 MHz or 50 MHz
>
> Looking forward for some help.
>
>
> Thanks & Regards,
> Anup Kini.
>
> On Tue, Jan 23, 2018 at 2:51 PM, Alex Bradbury <asb at lowrisc.org 
> <mailto:asb at lowrisc.org>> wrote:
>
>     On 23 January 2018 at 09:17, Anup Kini <anupkini at gmail.com
>     <mailto:anupkini at gmail.com>> wrote:
>     > Hi Jonathan,
>     >
>     > Thanks for pointing out the ethernet IP.
>     >
>     > Currently, I need to boot linux on a RISC-V based system and
>     found lowrisc
>     > to be simple and easy to follow.
>     > I can do without the ethernet IP for now, login through the UART
>     interface
>     > and work on building a open-emdedded layer for the filesystem.
>     > I did look at the v0.2, untethered version also, the main point
>     being easy
>     > to port to the Virtex 2000T boards that I have here.
>     >
>     > The end goal would be to integrate with REDEFINE, a massively
>     parallel many
>     > core architecture (this work was presented at the RISC V
>     Workshop 2016. Video
>     > @ 7:40 mins <https://www.youtube.com/watch?v=PCzAOYJa-xY
>     <https://www.youtube.com/watch?v=PCzAOYJa-xY>>)
>
>     Interesting, are there any published papers on REDEFINE?
>
>     Best,
>
>     Alex
>
>



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