ESP32-S3R8 PSRAM GPIOs

[MasterOfReality]

Hello there,

I have custom design based on ESP32-S3R8, and by mistake I connected two pins used by the in-package PSRAM, GPIO36 and GPIO37, to another component in the design, which can utilize the state of those two pins to enter low-power mode and reset.
Fortunately, the component can function properly even without those two pins, but they should be floating.
I need to use the PSRAM of the ESP.

My question is, when using the PSRAM, is there any activity on GPIO36 and GPIO37, or GPIO36 and GPIO37 pads are floating, in which case I don't need to make any modifications to the PCB design, but just ensure that I don't change the functionalities of GPIO36 and GPIO37 in firmware?
Or I mustn't connect anything to those pads?
I don't have access to scope currently to check, and I need confirmation if those physical pins are floating, and the SPI connections are just internal, in the package of the ESP.

Thank you in advance.

[ESP_Sprite]

No, GPIO36 and 37 are part of the data bus and clock system for the PSRAM - there'll always be some activity on those when using the PSRAM and they can't be floated.

[MasterOfReality]

Is it possible to utilize GPIOs Input Enabled and Output Enable control signals, to disconnect the GPIO from the physical pad?
Or this will cause issues with the PSRAM?

image (2).png (45.82 KiB) Viewed 1008 times

[ESP_Sprite]

Yes. These GPIOs need to carry signals in order to communicate with the PSRAM; if you float them, no PSRAM communication is possible.

[MasterOfReality]

Thank you very much for your responses!