Author Topic: Ethernet on K66 with kz8081 PHY  (Read 188 times)

Offline BrandonT

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Ethernet on K66 with kz8081 PHY
« on: March 06, 2020, 05:08:22 PM »
I am working on getting Ethernet up and running on our custom board (with a K66 MCU) using uTasker.

I am seemingly able to configure the PHY (kz8081RNA) and read its registers, but I am not able to successfully establish a link.

When I have an ethernet cable plugged in, bit 4 of register 0x1E indicates, as expected, that signal is present on the RX differential pair. However, bit 8 never indicates a 'link up' condition.

Once the PHY is configured, is there anything that my app must do to allow a link to be established (other than avoid putting the PHY in reset, of course)?

Thank you.

Offline mark

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Re: Ethernet on K66 with kz8081 PHY
« Reply #1 on: March 06, 2020, 09:02:02 PM »

Do you use the same circuit as the FRDM-K66F board?

I am assuming that you have DEVELOP_PHY_CONTROL enabled in debug.c, which adds the PHY register dump. This also allows changing the PHY settings to test the effects of modifying registers.

The PHY will usually be set to auto-negotiation mode during the configuration and nothing else is needed to get a link-up state. This means that it is not normal that there is no link up state after a second or two following connection of the cable. If possible I would do a comparison of the PHY register states after initialisation (without inserted cable, and then with inserted cable) between your board and the FRDM-K66F board to see whether there are any obvious differences in behavior (apart from the link-up state not being displayed).