ESP32 Forum

I have my esp32_Devkitc_v4 working with the LAN8720. I followed this wiring diagram https://sautter.com/blog/ethernet-on-es ... g-lan8720/ like many before me I'm sure. The issue is that the article talks about "GPIO0 is pulled LOW during the bootup sequence the bootloader awaits serial programming.". So since I am using GPIO0 for the LAN8720 and pulling it HIGH, how can I wire it to do both. So for normal running pull the pin HIGH but for flashing keep it LOW. I am fairly new to this but am wondering if I just need a button to pull it LOW when I want to flash the board and pull HIGH during normal operation. So push button to flash sort of thing. I have no idea how to wire something like this up and am not even sure if I am on the correct path. Any help would be appreciated.

The problem is the 50MHz oscillator on the LAN8720 board: it changes IO0 between high and low, so 50% chance the ESP32 will boot.
As Sautter explains: he disables the oscillator during booting.
It's not only a problem with flashing, but every time the ESP starts up.
You can interrupt the wiring between IO0 (ESP) and REFCLK (LAN8720) with a switch, but you have to do that every time ESP starts up.

I've done this interruption with an optocoupler: not the most elegant way, but it's working
(+3.3V is any output port)