Does GPIO17 use as a EMAC_Clock?

[yagnik.pokal]

Hello,
I m making an ESP32f custom board with ethernet.

in ESP32 GPIO0 is multiplexed with serial programming mode and Ethernet clock.

so I have a requirement to use Ethernet and Serial programming at the same time.

I am communicating LAN8720 PHY chip for EMAC.

I have found that GPIO17 also can be used as an Ethernet clock.so that I can use GPIO0 as a serial programming mode and GPIO17 as an EMAC_CLOCK.

I have a few questions.

1) should I use GPIO17 as an EMAC clock?
(As mentioned in the link:- https://github.com/espressif/esp-idf/tr ... t/ethernet )

2) does it required external ICs (inverter of the clock)?

3) If I configure GPIO17 as an EMAC_Clock should I need to do extra changes in Hardware or firmware?

[mikemoy]

I just tried this for you. It does work using GPIO17 as the EMAC_CLOCK.
Though it seems to take a few more seconds to get the DHCP, and a bit longer to serve a web site.
Something just feels a bit hankey using GPIO17 vs GPIO0, if you know what I mean.
I am attributing this to the long lead wires I am using from board to board, as its just not a good idea to push 50MHZ through a long wire like this. If this circuit was on a PCB it would be ok.

Update: I used 3 ribbon cable wires. The two outside wires are attached to GND, and the center was used for the clock.
This made it work just fine.

This is the board i have tried it with.
https://www.amazon.com/gp/product/B0150 ... UTF8&psc=1

Note, if using this board, you will need to mod it a bit.
Following the directions here.