Pull up does not work.

Saichander
Posts: 4
Joined: Tue Oct 17, 2023 11:53 am

Pull up does not work.

Postby Saichander » Fri Sep 20, 2024 10:36 am

The signal lines RWA_ALARM, NORMAL_BETRIEB are pulled up (at first internal pull up it did not worked and after that in the pcb I have externally pulled up as well) but the voltage level on those lines are around 1-1.5 volts.

If anyone knows the reason/solution please let me know. (if there are any mistakes which I did please let me know)

Thanks in advance.
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felmue
Posts: 70
Joined: Mon Nov 16, 2020 2:55 pm

Re: Pull up does not work.

Postby felmue » Fri Sep 20, 2024 12:49 pm

Hello @Saichander

have a look here: https://docs.espressif.com/projects/esp ... /gpio.html. GPIO34 to GPIO39 don't have internal pull-up (or pull-down) capabilities.

Excerpt from that page: GPI: GPIO34-39 can only be set as input mode and do not have software-enabled pullup or pulldown functions.

As for the external pull-ups - maybe they are too weak?

Thanks
Felix

ESP_Sprite
Posts: 9715
Joined: Thu Nov 26, 2015 4:08 am

Re: Pull up does not work.

Postby ESP_Sprite » Sat Sep 21, 2024 12:25 am

How is the schematic bit that derives those two signals supposed to work? If any, I don't see a way for the MOSFETs to stop conducting: as soon as they start conducting (and the gate capacitance is charged) there's no way for the gate capacitance to discharge again.

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