On Sat, 8 Mar 2008 10:18:21 -0000, "Andrew Holme" <ah@nospam.co.uk>
wrote:
>
><sky465nm@trline5.org> wrote in message news:fqtcpv$c88$1@aioe.org...
>> When using a gigabit ethernet PHY. Does it matter if one wires the
>> magnetics
>> with the "wrong" polarity like below ..?
>> (reason being pcb routing, and the ethernet transformer isn't
>> straightforward)
>>
>> From this: To this:
>>
>> RJ45 pin1 --- MX1+ ** TD1+ --- MDIA_P RJ45 pin1 --- MX1- ** TD1- ---
>> MDIA_P
>> RJ45 pin2 --- MX1- ** TD1- --- MDIA_N RJ45 pin2 --- MX1+ ** TD1+ ---
>> MDIA_N
>>
>> RJ45 pin3 --- MX2+ ** TD2+ --- MDIB_P RJ45 pin3 --- MX2- ** TD2- ---
>> MDIB_P
>> RJ45 pin6 --- MX2- ** TD2- --- MDIB_N RJ45 pin6 --- MX2+ ** TD2+ ---
>> MDIB_N
>>
>> RJ45 pin4 --- MX3+ ** TD3+ --- MDIC_P RJ45 pin4 --- MX3- ** TD3- ---
>> MDIC_P
>> RJ45 pin5 --- MX3- ** TD3- --- MDIC_N RJ45 pin5 --- MX3+ ** TD3+ ---
>> MDIC_N
>>
>> RJ45 pin7 --- MX4+ ** TD4+ --- MDID_P RJ45 pin7 --- MX4- ** TD4- ---
>> MDID_P
>> RJ45 pin8 --- MX4- ** TD4- --- MDID_N RJ45 pin8 --- MX4+ ** TD4+ ---
>> MDID_N
>>
>>
>> Magnetics schematic:
>> http://www.freeimagehosting.net/uploads/1b29a64249.jpg
>>
>
>No, it doesn't matter, not if you reverse both TD and MX pairs as you have.
>
This is part of the reason auto MDI and auto MDIX have become common
in routers and switches.
<sky465nm@trline5.org> wrote in message news:fqtcpv$c88$1@aioe.org...
> When using a gigabit ethernet PHY. Does it matter if one wires the
> magnetics
> with the "wrong" polarity like below ..?
> (reason being pcb routing, and the ethernet transformer isn't
> straightforward)
>
> From this: To this:
>
> RJ45 pin1 --- MX1+ ** TD1+ --- MDIA_P RJ45 pin1 --- MX1- ** TD1- ---
> MDIA_P
> RJ45 pin2 --- MX1- ** TD1- --- MDIA_N RJ45 pin2 --- MX1+ ** TD1+ ---
> MDIA_N
>
> RJ45 pin3 --- MX2+ ** TD2+ --- MDIB_P RJ45 pin3 --- MX2- ** TD2- ---
> MDIB_P
> RJ45 pin6 --- MX2- ** TD2- --- MDIB_N RJ45 pin6 --- MX2+ ** TD2+ ---
> MDIB_N
>
> RJ45 pin4 --- MX3+ ** TD3+ --- MDIC_P RJ45 pin4 --- MX3- ** TD3- ---
> MDIC_P
> RJ45 pin5 --- MX3- ** TD3- --- MDIC_N RJ45 pin5 --- MX3+ ** TD3+ ---
> MDIC_N
>
> RJ45 pin7 --- MX4+ ** TD4+ --- MDID_P RJ45 pin7 --- MX4- ** TD4- ---
> MDID_P
> RJ45 pin8 --- MX4- ** TD4- --- MDID_N RJ45 pin8 --- MX4+ ** TD4+ ---
> MDID_N
>
>
> Magnetics schematic:
> http://www.freeimagehosting.net/uploads/1b29a64249.jpg
>
No, it doesn't matter, not if you reverse both TD and MX pairs as you have.
When using a gigabit ethernet PHY. Does it matter if one wires the magnetics
with the "wrong" polarity like below ..?
(reason being pcb routing, and the ethernet transformer isn't straightforward)
From this: To this:
RJ45 pin1 --- MX1+ ** TD1+ --- MDIA_P RJ45 pin1 --- MX1- ** TD1- --- MDIA_P
RJ45 pin2 --- MX1- ** TD1- --- MDIA_N RJ45 pin2 --- MX1+ ** TD1+ --- MDIA_N
RJ45 pin3 --- MX2+ ** TD2+ --- MDIB_P RJ45 pin3 --- MX2- ** TD2- --- MDIB_P
RJ45 pin6 --- MX2- ** TD2- --- MDIB_N RJ45 pin6 --- MX2+ ** TD2+ --- MDIB_N
RJ45 pin4 --- MX3+ ** TD3+ --- MDIC_P RJ45 pin4 --- MX3- ** TD3- --- MDIC_P
RJ45 pin5 --- MX3- ** TD3- --- MDIC_N RJ45 pin5 --- MX3+ ** TD3+ --- MDIC_N
RJ45 pin7 --- MX4+ ** TD4+ --- MDID_P RJ45 pin7 --- MX4- ** TD4- --- MDID_P
RJ45 pin8 --- MX4- ** TD4- --- MDID_N RJ45 pin8 --- MX4+ ** TD4+ --- MDID_N
Magnetics schematic:
http://www.freeimagehosting.net/uploads/1b29a64249.jpg