ESP32 Forum

Hello everyone!

I'm trying to read rfid-cards with rc522 and send info via ethernet on esp32wroom38pin. I have scheme to connect and it worsk well separately.

But scheme shows same pins for modules. I know I can change 18 and 32 pins for lan8720 and assign to others and it works. My problem is one common pin 19. Is it possible to change 19 pin for lan9720 or rc522? Or any other way to use both modules on my esp. I'm newbie any help appreciated.

You can remove my post and delete my acc since this forum gives nothing

Aorry for it dude, i pass throug the same, and i can't solve, did you find one way to that?

You cannot change GPIO for RMII EMAC. However, you can use whatever IO pin (via IO Matrix) for SPI if you don't need high speed SPI CLK (more than 26.6 MHz).

ESP_ondrej wrote: ↑

Mon Aug 14, 2023 11:09 am

You cannot change GPIO for RMII EMAC. However, you can use whatever IO pin (via IO Matrix) for SPI if you don't need high speed SPI CLK (more than 26.6 MHz).

so, how would you recommend me to connect all lan8720 with rfid? I didn't understand very well how all this would have to be done, if you could I would be grateful

Read documentation at https://docs.espressif.com/projects/esp ... ac-and-phy and get familiar with REF RMII CLK options. In case of LAN8720, I recommend to use GPIO17 as CLK source to avoid board reset and startup issues, see https://www.crowdsupply.com/silicogniti ... reset-saga. However note, that you need WROOM module to be able to use GPIO16/17 since WROVER modules use these pins for PSRAM. In addition make sure, there is no oscillator on your LAN8720 dev board.
Then connect the remaining LAN8720 pins to GPIO as described at https://github.com/espressif/esp-idf/tr ... s/ethernet

SPI device can be connected to whatever pins left unconnected. However, I recommend avoiding using ESP32 bootstrap pins. They can be handled but it requires extra care so it is better to not use them for simplicity. Check the modules datasheet to find which pins are bootstrap.