Unused pins on PCB

[morsisko]

Hello,

I'm designing PCB for my device, it will use ESP-WROVER module as main MCU. I can't find answer to my question in the datasheet nor on the forum. I'm using only half of the GPIOs, what should I do with unused pins? Is it ok to leave them float? Maybe I should connect them to VCC via pull-up resistor? This device will be powered from battery, so I want to avoid unnecessary power consumption. I'm aware that some of the GPIOs are the bootstrapping ones and need to be in certain state during boot, but what with the "normal" ones?
Thanks for answers

[ESP_Minatel]

Hi,

Since you can use the integrated pull-up and pull-down resistors, you can leave the pin unconnected and be sure to configure/initialize them in your software.

You can see the reference here for GPIO pull-up and pull-down: https://docs.espressif.com/projects/esp ... /gpio.html

Attention for this also:

Only pins that support both input & output have integrated pull-up and pull-down resistors. Input-only GPIOs 34-39 do not.

[morsisko]

Thanks for reply.

So just to clarify things, as for the GPIs in range 34-39 I'm using only GPI 34 and 35, so I assume I should connect external pull-ups to GPIs 36-39, because those pins don't have internal pull ups, is that correct?

[ESP_Minatel]

Hi,

I don't think it's necessary in your case, but there are some applications, like automotive, which recommend you to tie the pin to the ground using a resistor (pull-down).

[morsisko]

Thanks for you answers. I think it is clear now.
My application will operate in typical environment so I think I will let those GPI float.

[ESP_Minatel]

No problem!

The only reason for that is to keep all pins in a known state. Critical applications must be as safe as possible!