Wemos D32 Pro with Wemos TFT 2.4 shield, backlit issue

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sobolkz
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Wemos D32 Pro with Wemos TFT 2.4 shield, backlit issue

#1 Post by sobolkz » 26 Apr 2022, 05:34

Hi all!
Due to old discussions about GPIO states at deep sleep I'm searching way to control backlit as designed.
As we can see at board scheme and display shield there is additional pin, labeled as TFT_LED:
Shield.jpg
Shield.jpg (11.66 KiB) Viewed 4651 times
Wrover.jpg
Wrover.jpg (8.81 KiB) Viewed 4651 times
It can be used for brightness limitation by PWM at GPIO32 or backlit termination by changing GPIO32 to 0. All was checked and working perfect while board was running.
But then we want to turn board to deepsleep, GPIO32 goes to default state (which internally pulled up) and display backlit turning on again (without any information).
"Switch" config at GPIO32 with unchecked "Internal pull up" was checked without success. "Hardware" configuration for GPIO32 too - "Output low" can be applied only in running state.
External pull down 10K resistor also checked - GPIO32 state in deepsleep wasn't pulled to 0 with final voltage about 1.5V (which can't be recognised as LOW). Lowest resistanse will increase total scheme power consumption, which isn't good for me.
Is here any way, that can be used in this situation?

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ThomasB
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Re: Wemos D32 Pro with Wemos TFT 2.4 shield, backlit issue

#2 Post by ThomasB » 26 Apr 2022, 05:57

I suggest removing R2. Disable the GPIO32 pullup; Use GPIO32 pulldown feature or install an external 100K pulldown resistor.

- Thomas

sobolkz
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Re: Wemos D32 Pro with Wemos TFT 2.4 shield, backlit issue

#3 Post by sobolkz » 26 Apr 2022, 07:04

ThomasB wrote: 26 Apr 2022, 05:57 Disable the GPIO32 pullup; Use GPIO32 pulldown feature or install an external 100K pulldown resistor.

- Thomas
Hmm, as I wrote before -all already checked. I think 10K pulldown resistor better than 100K. "Hardware" page GPIO " Default pulldown" setting feature wasn't successful. ADC plugin "Pullup" feature also wasn't successful. Last both checked one by one, not at one time.
So, I can't find clarification of ESPEasy GPIO deep sleep states manipulation - is it right, that "Hardware" page GPIO " Default pulldown" and ADC plugin "Pullup" feature can be used in deepsleep state? and it should work for me?

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ThomasB
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Re: Wemos D32 Pro with Wemos TFT 2.4 shield, backlit issue

#4 Post by ThomasB » 26 Apr 2022, 07:24

Hmm, as I wrote before -all already checked.
But no mentioned that you remove R2. With it gone the off-state bias current will be reduced and the 100K pulldown should work. And maybe the internal pulldown will work in place of the external pulldown.

With R2 installed the off state current will be a few mA's. Remove it and it will probably be uA's.

- Thomas

sobolkz
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Posts: 37
Joined: 12 Sep 2019, 16:30

Re: Wemos D32 Pro with Wemos TFT 2.4 shield, backlit issue

#5 Post by sobolkz » 26 Apr 2022, 07:37

Ok, perfect, I'll try to remove R2.

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