Having some issue on Ethernet Phy clock on K60 Tower kit

[vallinaths]

Board:K60 , TWR SER

The Ethernet on TWR SER is working fine in the below clock configuration :

On TWR_SER

Jumper 3: CLOCKIN0 Driver Select (2-3) Route 50MHz clock to CLOCKIN0

Jumper 2 : Ethernet Phy Clock selct(3-4) 50 MHz

On K60 board

Jumper 10: Clock select (2-3) Connect EXTAL to the CLKIN0 signal on the elevator connector

In this configuration the Ethernet is working fine .

Tried another configuration where K60 board is working with clock from the external oscillator and ethernet Phy clock is Clockout and in this case the Ethernet is not working and not able ping the static iP.

Clock configuration in this case

On TWR_SER

Jumper 3: CLOCKIN0 Driver Select (2-3) Route 50MHz clock to CLOCKIN0

Jumper 2 : Ethernet Phy Clock selct(5-6) CLOCKOUT0

On K60 board

Jumper 10:Clock Input Source Selection (1-2) Connect main EXTAL to on-board 50 MHz oscillator

Please let me know anybody tried this configuration and any changes need to made to make it work .

[melissa_hunter]

Unfortunately, we have several types of TWR-K60 boards and of those types of boards there are several revisions. So the information you've provided doesn't tell me exactly what you are doing.

I can tell you that if you want to use the ethernet in RMII mode, then you need to use the 50MHz clock from the TWR-SER as the EXTAL (or EXTAL0) clock input to the processor. In RMII mode the ethernet controller uses the main clock input as the timing reference for the ethernet signals. If you use a 50Mhz clock, but from a different source, it can skew the signals and cause timing problems on the ethernet interface.

Based on your description it sounds like the second configuration you are using is using the clock source on the TWR-K60 board instead of the one from the TWR-SER. If so, then timing skew is most likely the cause of the ethernet issues.

Hope this helps,

Melissa

[vallinaths]

Hi Melissa ,

  Thanks for the reply !!!

Will post you the K60 board revision details tomorrow .

yes  the Second configuration mentioned above is not working ,

K60 chip is source to external clock source and the Ethernet Phy is getting the same clock from the clock out pin of the K60 processor .

In this configuration on the TWR-SER board measured  the clock output (Jumper 2 : Ethernet Phy Clock selct(5-6) CLOCKOUT0) and it is having 50Mhz frequency but the peak to peak voltage is very less around 200mvolts .is there any particular reason why  clockout0 cannot be used  or any other work around we have to use clockout0  as clock for Phy chip.

Thanks for the suggestion will use other way configuration of syncing  the clock source given to the Phy to the K60 controller .

Regards

vallinath

[melissa_hunter]

The ethernet controller in the K60 always using the EXTAL clock input as the reference for the RMII. So you can't use an output clock from the processor as the reference for the PHY (unless you also route that output clock to the processor on EXTAL0).

To put it another way, the RMII PHY clock must always be the same as the EXTAL (EXTAL0 for parts with two).

As I mentioned above you could theoretically route a clock that is output from the K60 back in on the EXTAL pin, but this is going to limit the clock modes available to you. You won't be able to use EXTAL to generate the output clock that creates EXTAL, so you'd need to use one of the internal refernces with the FLL (the internal referneces cannot be used to clock the PLL) or if you are using a part with two oscillators inputs you could clock the PLL from EXTAL1 (this method would require a clock on RTC_EXTAL though).

So it is going to add some compilications to your clock setup if you absolutely have to use an output clock for the RMII clock.  Overall I wouldn't recommend going this route particularly if you aren't using one of the parts with two crystal inputs.

-Melissa

[vallinaths]

Please anybody can suggest on the above discussion