ESP32 - added pull-up to 3.3V but measuring 1.6V

[velmurugan7kmvs]

Hi,

I have 3.3V pullup on all ESP32 GPIO pins.
The pull-up resistor value is 1Mohm.
However, I am measuring only 1.6V on the MCU IO pin.
I measured using multimeter.

What could be the reason?

The pull-ups are added on the following IO lines and readin 1.6V on all IOs.
GPIO36
GPIO39
GPIO34
GPIO35
GPIO32
GPIO33
GPIO25
GPIO26
GPIO15

[tommeyers]

on the esp32 datasheet pg 28, it says "each digital gpio can be configd with pullups or pulldowns"
There are several kinds of GPIOs: digital only GPIOs, analog enabled GPIOs, capacitive touch enabled GPIOs, etc.
Analog enabled GPIOs can be configured as digital GPIOs. Capacitive touch enabled GPIOs can be configured
as digital GPIOs.
Each digital enabled GPIO can be configured to internal pull-up or pull-down, or set to high impedan


Did you configure the pull up/down in code?

It looks like you don't need pu resistors with this available in code.

1M?

[velmurugan7kmvs]

Hi @tommeyers,

Thanks for your response.
I enabled pull-up and still measuring the same 1.6V.
Code screedhot attached

[velmurugan7kmvs]

I removed 1Mohm pull-up resistor on one of the GPIO and read 0V.
As we enabled the pullup resistor, the pin voltage is expected to be 3.3V. I am not sure what would be an issue.

[velmurugan7kmvs]

Even if i configure the pin as output and make it is HIGH or low, I am reading 1.6V only. Totally weird to me.


void setup() {
// put your setup code here, to run once:
Serial.begin (115200);
Serial.print("Serial Init Success");
pinMode(39, OUTPUT);
}

void loop() {
// put your main code here, to run repeatedly:

Serial.println("Start");
delay (500);
digitalWrite(39, LOW);
}

[ESP_Sprite]

Note that pins >34 do not have output or pullup/pulldown capability.

[velmurugan7kmvs]

Hi ESP_Sprite,

I configured it as general input GPIO and i have an external pull-up resistor 1Mohm, but still measuring 1,6V only?
I added pullup to 3.3V.

Regards.
Velmurugan

[velmurugan7kmvs]

Hello All,

It was my multimeter loading the IO lines and reading it as 1.6V instead of 3.3V.
Thanks to all members who commented.