I would like to use an 10/100/1000Mbps Ethernet transceiver for
switching between 1000Mbps Ethernet and 100Mbps Ethernet.
I am planning a redesign of an i.MX6 board which offers various
interfaces (I2C, SPI, USB, 100Mbps Ethernet, ...) over a 40-pin
connector to another board which has the magnetics and the connector for
During the redesign process Gigabit Ethernet shall be added (because the
processor can deliver it). However, I don't have enough lines left on
the connector to add this.
But on the new version the same 40-pin connector will get assembled a
second time (as an assembly variant) for optional additional interfaces.
This way the new version stays compatible to older boards. My idea was
that I will route the 4 differential pairs for Gigabit-Ethernet to the
new connector and the 2 already used pairs also to the old existing
connector. So these 2 pairs will get routed to both connectors. My idea
was to use 0 Ohm resistors to switch between the variants.
On the boards with the connector I would also use 0 Ohm resistors to
select the right mode and then route the differential pairs to the
magnetics and the RJ45 jack (maybe I will choose a RJ45 jack with
This way I could stay compatible to already existing boards by using the
And if 1000Mbps are wanted, I could assemble the new connector and
switch the 0 Ohm resistors to get Gigabit-Ethernet.
Do you understand my question or would a small sketch be helpful?
Do you think it could work this way? Do you think the 0 Ohm resistors
are a good idea or that this idea could work?
I am thankful for all input!