ESP32 - I2S / I²S - Can I really use any pin?

[bastian.h.jaeger]

Hello,

I am trying to create a custom ESP32-wroom based PCB with an I²S microphone.
As the PCB has more tasks to fulfill, the GPIOs are becoming rare. So I can not use any pin anymore.

I read a lot in the [Technical Reference Manual][https://www.espressif.com/sites/default ... ual_en.pdf] but I do not understand everything 100%.

As far as I understand, ws_io_num and data_out_num can be any pin, but bck_io_num can only be some specific pins, but I do not understand which!

Can someone tell me, which pins I can use for I2S?

[bastian.h.jaeger]

Anyone can refer to anythine or anyone?

[ESP_Sprite]

Where specifically do you read that BCK_IO_NUM is limited wrt pins to choose from?