ESP32-PICO-V3 Pin28 SD2/IO9 appears to have pull-up

[TerryBarnaby]

Hi,

I am just testing a new ESP32-PICO-V3 board that I have designed. It is generally working, but I have an issue with the Pin28 SD2/IO9 line. According to the datasheet this pin is usable as a GPIO line. Indeed it looks like I can drive this as an output.

However, it looks like by default when the CPU powers up this line is pulled fairly strongly high (which turns on an LED I have connected to it via an NMOS driver).

Is this to be expected ?
It almost looks like the 10k pull-up resistor that is used in an ESP32-PICO-V3-02, the one with the PSRAM, is actually in circuit.

[boarchuz]

Pullup is enabled by default on this pin. See datasheet appendix 4 "IO MUX". These are typically around 40-50k iirc.

[TerryBarnaby]

Many thanks.
I will need to use a different pin
Is there any info on which pins have pull-ups/pull-downs by default ?

[TerryBarnaby]

Ah, I see the default pullup/pulldowns are defeined in the ESP32 datasheet, not the ESP32-PICO-V3 datasheet.

[TerryBarnaby]

Its a great shame so many ESP32 IO pins have weak pull-ups enabled by default. I am producing a low power, battery powered system and some of these lines are driving the gates of MOSFET's to turn on high current devices. It's not nice these power on after a reset. I will have to move those lines to other pins, but really all of my pins should be low/OC at reset, but that does mess up the PCB layout and reduces the flexibility of the ESP32's otherwise flexible IO multiplexor.

I assume there is no OTP fuse that can disable most of the weak pull-ups ?