Re: [oc] I2C noise filtering

["kinysh asdf" <kinysh@hotmail.com>]

I do not think you need extra pins for this in xilinx.

Xilinx have BUFG, the input of it is a internal net, the output is to the 
global clock tree, you can use this cell to connect the internal generated 
signal to the clock tree.

Bests
kinysh


>From: Richard Herveille <richard@asics.ws>
>Reply-To: cores@opencores.org
>To: cores@opencores.org
>Subject: Re: [oc] I2C noise filtering
>Date: Tue, 26 Nov 2002 07:33:32 +0100
>
>
>
>IMHO an expensive suggestion.
>Is this a Xilinx topic?? I know Altera doesn't really care wether you put 
>scl
>on a GPIO or a dedicated clock pin. It automatically reroutes the signal to
>the dedicated hi-speed clock lines in the device. Timing might be affected
>though; caused by the additional delay, and the rerouting uncertainty 
>(added
>clock jitter).
>
>Richard
>
> >    Hi,
> >
> >          Or use two pin the Gclk for input and a general IO to streach 
>and
> > connect both to the external SCL line thus "enjoying from both world"
> > meaning easier routing as well as capable to streach the clock.
> >
> > Of course you "pay" for this in extra pin but I would assume in most 
>cases
> > you have this extra pin and the gain might even allow you to use smaller
> > device.
> >
> > have a nice day
> >
> >    Illan
> >
> > -----Original Message-----
> > From: Richard Herveille [mailto:richard@asics.ws]
> > Sent: Monday, November 25, 2002 10:50 AM
> > To: cores@opencores.org
> > Subject: Re: [oc] I2C noise filtering
> >
> >
> >
> > You are talking about the i2c slave again right??
> > Both SCL and SDA are bidirectional signals (inout). So you probably do 
>want
> > to
> > use general purpose IOs for SCL and SDA. Unless you do not support clock
> > stretching (wait state generation), in that case you can use a global 
>clock
> > pin for the SCL line. Although I2C is so slow it shouldn't matter (might
> > ease
> > up routing in you FPGA though).
> >
> > > my clock is 10mhz (xilinx) and both sda and scl is tied to general IO.
> > >  So, like you said,  I have to output po_scl_cln to another general IO
> > > and and tie it to Global clk pin?  Is there any way to avoid it
> > > because it's too difficult to solder such a small and close pin chip.
> > >  And also, I thought start and stop condition will reset all, but why
> > > there is another reset for it?  Since I don't have choice for reset on
> > > the board, will that be an issue?
> > >
> > >
> > >
> > > Ken
> > >
> > > ----- Original Message -----
> > > From: Illan Glasner <IGlasner@m... >
> > > To: "'cores@o... '" <cores@o... >
> > > Date: Wed, 6 Nov 2002 19:14:54 -0800
> > > Subject: RE: [oc] I2C noise filtering
> > >
> > > > Hi,
> > > >
> > > >    You can try something like :
> > > >
> > > > reg     [2:0]   scnt;
> > > > always @(posedge pi_clk or negedge rstn)
> > > > if (~rstn)
> > > >    scnt <= #1 0;
> > > > else if (scl)
> > > >    scnt <= #1 (scnt==7) ? 7 : scnt + 1 ;
> > > > else
> > > >    scnt <= #1 (scnt==0) ? 0 : scnt - 1 ;
> > > >
> > > > reg     po_scl_cln   ;
> > > > always @(posedge pi_clk)
> > > > if (~rstn)
> > > >    po_scl_cln <= #1 0;
> > > > else
> > > >    po_scl_cln <= #1 scnt[2] ;
> > > >
> > > >
> > > > keep in mind that if you use Xilinx you probably will need to send
> > > > po_scl_cln to a general IO make an external connection on the board
> > > > to GCLK
> > > > IO in order to use the clock resource.
> > > >
> > > > if you are using altera in this matter it should be easier as you
> > > > can use
> > > > directly the po_scl_cln.
> > > >
> > > > where pi_clk is a high frequncy clock much faster than the scl
> > > > something
> > > > like 10M.
> > > >
> > > > if you don;t have high frequnacy you can make another "loop" of
> > > > geenral IO
> > > > to GCLK input and simple generate internaly a free runing ring osc
> > > > using let
> > > > say 6 buffer and invertor and this should do the job.
> > > >
> > > > have a nice day
> > > >
> > > >    Illan
> > > >
> > > >
> > > >
> > > > -----Original Message-----
> > > > From: ckh827@h...  [mailto:ckh827@h... ]
> > > > Sent: Wednesday, November 06, 2002 8:01 PM
> > > > To: cores@o...
> > > > Subject: [oc] I2C noise filtering
> > > >
> > > >
> > > >
> > > >
> > > > When I try to synthesize the I2C verilog from Richard (Opencores),
> > > > It
> > > > said unable to open timescale.v. But I already added the source in
> > > > the
> > > > project.  Anybody has any idea?
> > > >
> > > > And also, how can I filter out the noise from scl and sda lines?
> > > >
> > > > I'm urgently need a working I2C slave model because I already
> > > > worked
> > > > for more than 3 weeks but still not able to ping correctly.
> > > >
> > > > Any help is appreciated.
> > > >
> > > > Ken
>
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