Hi,
I am having a problem with an LPC2468 that is being used in conjunction with a
Micrel KS8999 Ethernet switch (using MII).
The problem is that any attempt to interrogate the PHY registers seems to comes
back with no response. The code is similar (if not identical) to the example
code supplied by NXP for the purpose and attempts to read the PHY ID registers 1
& 2 to determine the address of the device. But after the read the MIND and MRDD
registers are both 0x00.
I've also attempted to read the PHY BMSR with a similar(ish) result except
the MIND MII_LINK_FAIL bit is being set to 1.
The complication I have is that the hardware was designed without the MDIO/MDC
pins being connected to anything (don't ask me why the hardware team have
designed it this way, I'm just expect to get it working!). So my question
is, is it actually possible to interrogate the PHY registers without these pins
attached? Or is the request/response transmitted over the 7 wire MII interface
itself?
Any help gratefully received
Steve.
LPC2468 and PHY registers on a Micrel switch
Started by ●July 13, 2009
Reply by ●July 13, 20092009-07-13
>> without the MDIO/MDC pins being connected to
anything
There's your problem. The MII Management Communication happens across these lines. The data bus lines are used just for that, data.
>> I'm just expect to get it working
I don't see how without those lines hooked up.
Chris.
There's your problem. The MII Management Communication happens across these lines. The data bus lines are used just for that, data.
>> I'm just expect to get it working
I don't see how without those lines hooked up.
Chris.
Reply by ●July 16, 20092009-07-16
--- In l..., "Chris_S" wrote:
>
> >> without the MDIO/MDC pins being connected to anything
>
> There's your problem. The MII Management Communication happens across these lines. The data bus lines are used just for that, data.
>
> >> I'm just expect to get it working
>
> I don't see how without those lines hooked up.
>
> Chris.
>
>
>
Thanks Chris, that confirms my assessment which is good. Have handed it back to the Hardware team but they are currently still claiming it can be done without MDIO. Until they can prove that I'm not touching it again!
>
> >> without the MDIO/MDC pins being connected to anything
>
> There's your problem. The MII Management Communication happens across these lines. The data bus lines are used just for that, data.
>
> >> I'm just expect to get it working
>
> I don't see how without those lines hooked up.
>
> Chris.
>
>
>
Thanks Chris, that confirms my assessment which is good. Have handed it back to the Hardware team but they are currently still claiming it can be done without MDIO. Until they can prove that I'm not touching it again!
