Re: [lwip-users] Ethernet package through SPI interface

[Noam Weissman]

Hi,

Thanks that gives some interesting ideas.

BR,
Noam.

-----Original Message-----
From: address@hidden [mailto:address@hidden On Behalf Of SergeV
Sent: Monday, March 14, 2016 1:25 PM
To: Mailing list for lwIP users
Subject: Re: [lwip-users] Ethernet package through SPI interface


Hi Noam ,
You are right, LwIP doesn't interface to RMII (direct).
I does however in most cases, through driver. 

RMII is still a "too many wires" port, and therefore folks often talk about 
options to reduce this set. 
I'm happy that my 2cents resulted in a friutful discission (and even we now 
know the way to use SPI for that).

On my side, I happened to write a NC-SI LwIP driver (NXP LPC1768 platform) 
which requires no MDIO for PHY configuration, and therefore is 2 wires less 
wide than RMII is.
While not many chips support NC-SI, maybe this my $1 addition will be helpful 
to somebody (attached is a NC-SI driver for LwIP source).

Sorry, I'm not that fluent with LwIP internals to store the code to the sorces, 
therefore I'm attaching it here. Feel free to do whatever you like with it, or 
to ask questions.

rgds,
SergeV

> Noam,
>
> I'll have to add some more here:
>
> Noam Weissman wrote:
>>  [..]
>>  The ETH PHY is connected from one side to the magnetics and from the other 
>> side it has a MAC interface.
>>  [..]
>>  LwIP or any other TCP stack need to read/or data to/from the MAC 
>> interface. This is the hardware driver that connects
>>  the LwIP with the hardware.
>
> These words might imply lwIP connects to RMII, but it doesn't. The 
> interface between lwIP and the MAC can be a parallel bus (e.g. MAC 
> included in the micro or external MAC connected to a memory-mapped 
> bus), or a serial interface (e.g. SPI) or anything else.
> The MAC then converts to (R/G/whatever)-MII, followed by the PHY 
> converting to the media.
>
> I wrote this only to make it clear that lwIP does not in any way 
> interface MII.
>
> Simon
>
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