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The problem of logic synthesis   Message List  
Reply | Forward Message #15850 of 16506 |
Re: The problem of logic synthesis

--- In leon_sparc@yahoogroups.com, Jiri Gaisler <jiri@...> wrote:
>
>
> The best solution is to switch to leon3 (you are using leon2), which
> does not use the inverted clock.
>
> Jiri.
>
> gyuekjay wrote:
> > Hi,Gaisler Team,
> > In tech_map.vhd,entity regfile_iu include a dpram with two clks that named
clk and clkn(clkn=not clk).
> > When i did logic synthesis,the period of time path between clk and clkn is
half of the period of sysclk.So the time report have some violations.The tool is
DC 2002,and the library is slow of smic18.The period of sysclk is 7.6ns. I dont
know how to deal with this probrem, hope someone could give me some suggestions.
> > Thank you very much!
> >
> >
> >
> > ------------------------------------
> >
> > Yahoo! Groups Links
> >
> >
> >
> >
>
> The best solution is to switch to leon3 (you are using leon2), which
> does not use the inverted clock.
---
Hi,jiri,
Thank you for your reply,but i dont know why the leon2 does not use the
inverted clock,in fact ,i find the module of proc use clk and clkn in
mcore.vhd,the module of regfile_iu in leon2 and leon3 include the dpram which
has two clk port,the difference between the leon2 and leon3 is:

leon2->the two clk port connect to clk and clkn(mocre.proc.iu.regfile_iu ),and
if the two clk port both connect to clk,then the simulation will fail
/*proc0 : proc port map (
rst, clk, clkn, apbi(2), apbo(2), ahbmi(0), ahbmo(0),
ahbsi(0), iui, iuo);*/
------------------------------------------------------------------

leon3->the two clk port both connect to clk(leon3mp.leon3sh.regfile_3p),and the
simulation will pass
/*-- IU register file

rf0 : regfile_3p generic map (memtech, IRFBITS, 32,
syncram_2p_write_through(memtech), IREGNUM)
port map (clk, rfi.waddr(IRFBITS-1 downto 0), rfi.wdata, rfi.wren, clk,
rfi.raddr1(IRFBITS-1 downto 0), rfi.ren1, rfo.data1,
rfi.raddr2(IRFBITS-1 downto 0), rfi.ren2, rfo.data2, rfi.diag);*/
--------------------------------------------------------------------
The best solution is to switch to leon3 ,that is a good suggestion.
But now i must insit on using leon2, i can use the inverted clock,but the system
frequency will be lower than using the clock,
the leon3 only use a clock ,so the system frequency will be higher and the logic
synthesis will not have the problem which i have found in leon2,is right?

Thank you very much!






Mon Jul 13, 2009 8:10 am

gyuekjay
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Message #15850 of 16506 |
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Hi,Gaisler Team, In tech_map.vhd,entity regfile_iu include a dpram with two clks that named clk and clkn(clkn=not clk). When i did logic synthesis,the period...
gyuekjay
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Jun 23, 2009
9:30 am

The best solution is to switch to leon3 (you are using leon2), which does not use the inverted clock. Jiri....
Jiri Gaisler
jiri_gaisler
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Jun 23, 2009
12:06 pm

... Hi,jiri, Thank you for your reply,but i dont know why the leon2 does not use the inverted clock,in fact ,i find the module of proc use clk and clkn in...
gyuekjay
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Jul 13, 2009
8:11 am

The leon3 pipeline is deeper than leon2, to avoid using the negative edge on the clock. This will allow leon3 to reach higher frequencies compared to leon2. ...
Jiri Gaisler
jiri_gaisler
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Jul 13, 2009
4:06 pm
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