WROVER module with LAN8720A

[zliudr]

I'm trying to put together a design with WROVER and LAN8720A. Based on existing designs such as the one with WROOM and LAN8720A, GPIO17 is used as EMAC_CLK_OUT. I wonder if there are any alternative pins for EMAC_CLK_OUT. Since WROVER uses GPIO17 for SPIRAM, if I can't use a different pin, then I'm stuck with WROOM only. It's good to know what my options are. Thanks.

[username]

You can use GPIO0

[zliudr]

OK thanks. GPIO0 has CLK_OUT1 feature. I'll do some tests once I have WROOM+LAN8720A dev boards in hand. Does the trace have to have some impedance matching due to 50MHz frequency?

[username]

I did this many years ago, so I am not sure what has changes in the software. But back then you could configure to use GPIO0 as the clk.
The problem with this was that it did not allow uploading the firmware automatically. You had to manually keep GPIO0 low then reset to put it in bootloader mode for downloading. I didn't like this approach so I did it this way instead.

ESP32-WROVER v0.6.jpg (2.33 MiB) Viewed 2699 times

I dont use that design anymore, mainly because I only use the ESP32-S3, and there is no stock of the LAN8720A. When I need Ethernet I use the KSZ8851SNL Ethernet Controller. Works great. There is even an example to get you going here:
https://github.com/espressif/esp-idf/tr ... rnet/basic

[zliudr]

Thanks for sharing. I didn't check stock of LAN8720A. I guess that's another reason to not use it, besides having to rig some mechanism on GPIO0 for uploading. I'm using micropython so my support is very limited, either the LAN8720A (and a few other PHY chips I can look for stock) or wiznet W5500, which I'm struggling to make work.