RE: [ethmac] New host interface (without DMA)

["Igor Mohor" <igorm@opencores.org>]

CPU stores data somewhere in the memory and writes this address as source
address to the DMA descriptor. For destination address ethernet MAC address
is used (see ethernet.top file):

If you look at this file you'll find this lines:
assign RegCs = wb_stb_i & wb_cyc_i & DWord & ~wb_adr_i[11] & ~wb_adr_i[10];
assign BDCs  = wb_stb_i & wb_cyc_i & DWord & ~wb_adr_i[11] &  wb_adr_i[10];

So wb_adr_i[11] & wb_adr_i[10] must be both one for the data to come to the
right place and not to registers or buffer descriptors.

When ethernet MAC will start to work, it will assert the DMA_REQ and DMA
engine will provide the appropriate data to the ethernet mac.

Regards,
	Igor

PS.
I want to use ethernet MAC without DMA block and that is the reason I'm
cutting it out and adding wishbone master interface to it. In this version
without DMA, ethernet MAC will go and access data from the memory by itself.
The destination of the frame in the memory will be also written in the tx
and rx buffer descriptors within the ethernet MAC.

> -----Original Message-----
> From: owner-ethmac@opencores.org [mailto:owner-ethmac@opencores.org]On
> Behalf Of satya
> Sent: 3. januar 2002 12:23
> To: ethmac@opencores.org
> Subject: Re: [ethmac] New host interface (without DMA)
>
>
>
> Hi Igor,
> thanks for your kind reply.You said that u r not using DMA descriptors
> anywhere in the core.If so,in case of trnasmitting a frame,how the
> descriptors will be loaded with source address and destination
> address which
> are stored only in DMA descriptors.I want to know how you are
> accessing  the
> DMA?
> Pls do reply me immly.
>
> Thanks and Regards
> - satya
>
>
> > I use only tx descriptors in my core. DMA descriptors are not used
> anywhere
> > in the ethernet MAC core. At the moment host interface only supports DMA
> > accesses and for that reason DMA core needs to be used.
> > http://www.opencores.org/projects/wb_dma/
> > How to use DMA descriptors, read the DMA documentation.
> >
> > I'm working on the host that doesn't need DMA and has wishbone master
> > interface for that purpose. It will take me few more days to finish.
> >
> > So, there are three possibilities:
> > - use DMA core
> > - wait for few days until I finish the new host interface
> > - write your own interface
> >
> > Regards,
> > Igor
> >
> >
> >
> > > -----Original Message-----
> > > From: owner-ethmac@opencores.org [mailto:owner-ethmac@opencores.org]On
> > > Behalf Of satya
> > > Sent: 3. januar 2002 9:52
> > > To: ethmac@opencores.org
> > > Subject: Re: [ethmac] art_hsdp_256x40.v
> > >
> > >
> > > Hi Igor,
> > > If we consider the trnasmitting frame direction,u have defined
> > > two types of
> > > descriptors Tx buffer descriptors and DMA descriptors.But while going
> > > through the core,I found nowhere those descriptors
> used.Please point me
> to
> > > the descriptors in the core.I am waiting for ur reply.
> > >
> > > Thanks and Regards
> > > - satya
> > >
> > > --
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