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

[Matthias]

Hello Jean Pierre,

>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). 

Thanks for the info.

>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.  

I understand:
switch => full-duplex
HUB => half-duplex

What happens when I use full-duplex with an half-duplex device/HUB ?
Get I any special error from the RTL8019AS, that I can reconfigure the NIC to 
half-duplex ?


When we connect the EDO line to VCC with a resistor, we get all bits to 1 in 
the CONFIG3 register.
Then we have the FUDUP bit at 1 => full duplex.

In the nictrl.c (Revision 1.8) we emulate the EEPROM and write 0x30 to the 
CONFIG3 register.
Then we have the FUDUP bit at 0 => half duplex.


Is that right ?


Thank you very much for your help !


Best regards

Matthias