[En-Nut-Discussion] Understanding the Ethernut 1.3G design(RTL8019AS)

[Jean Pierre Gauthier]

Matthias,
I use the $8400 -FFFF with the Ethernut 1.3.F for memory extension, around
60K memory at 0-FFFF (excluding ATMEGA128 and RTL8019)directly addressable
by the CPU and malloc() + banked 450K (addressed with IT masked). 

I don't think that Ethernut 1.3G is different for this usage. 
Harald sent a mail over this few months ago.  A story of RD/WR disabled when
the RTL is addressed. 
I hope that Harald is always OK....

Ethernet full-duplex is used when lines are connected to switchs or routers.
RX /TX can work simultaneously.  Ethernet half-duplex is the "old scheme"
when data are (were) carried over one shared Eth line or cross HUBs. You
talk an receive on the same line so that 4Mb/s (Eth10) is really usable with
collisions. Of course, full-duplex is better because the bitrate is really
2x10 Mb/s ( 2*X for EthX) without collisions.  

Jean Pierre



-----Message d'origine-----
De : en-nut-discussion-bounces at egnite.de
[mailto:en-nut-discussion-bounces at egnite.de] De la part de Matthias
Envoyé : dimanche 19 décembre 2004 16:49
À : en_nut_discussion at onlinehome.de; Ethernut User Chat
Objet : Re: [En-Nut-Discussion] Understanding the Ethernut 1.3G
design(RTL8019AS)

Hello,

can nobody help me at my questions ?


Best regards

Matthias


>Betreff : [En-Nut-Discussion] Understanding the Ethernut 1.3G design 
>(RTL8019AS)
>Gesendet: 17.12.2004 05:20:21
>An : "En-Nut <en-nut-discussion at egnite.de>"
>Von: "Matthias <en_nut_discussion at onlinehome.de>"

>----- Original Message -----
>Hello,

>I try to understand the ethernet part of the Ethernut 1.3G PCB.

>I have the following questions:

>1. Why is the complete address bus routed to the RTL8019AS, when he 
>only uses 0x8300-0x831F (0x300-0x31F)?
>   Or can I access the 16k SRAM via the other address lines ?
>   Can I use the adresses 0x8320-0xFFFF (and 0x8000-0x82FF) for an own 
>Add-On board ?

>2. What are the pros and cons of the EEPROM emulation ?
>   I readed something about half-/full-duplex. Can anyone explain me this ?


>(Until now I have no Ethernet knowledge besides socket programming.)


>Thank you very much for your help !


>Best regards

>Matthias
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