Weird behaviour on GPIO17 on WROOM32 module

RichPiano
Posts: 123
Joined: Mon May 18, 2020 2:51 pm

Weird behaviour on GPIO17 on WROOM32 module

Postby RichPiano » Wed Apr 28, 2021 9:20 pm

I have an application that uses PWM to drive 8 LEDs. Everything is working as expected and the LEDs lighten up as expected with the exception of GPIO17. The LED on this pin is only "glowing" lightly although it has the same voltage output as all the other pins (~3.2V). I figured it must have something to do with the inherent characteristics of that pin.

Things I tried:
- As the pin is listed in the GPIO layout of WROOM32 as TX pin () I tried disconnecting the EPS32 from my USB (which I thought could interfere with TX/RX capabilities of the chip) and supply voltage over VIN, but even then the GPIO only shows the above described behaviour.
- Tried using a different ESP32

But nothing helped. So what is up with GPIO17?

ESP_Sprite
Posts: 9746
Joined: Thu Nov 26, 2015 4:08 am

Re: Weird behaviour on GPIO17 on WROOM32 module

Postby ESP_Sprite » Thu Apr 29, 2021 12:46 am

You're sure you're using a WROOM module? In a WROVER, this pin is taken up by the PSRAM. Also, what SDK are you using?

RichPiano
Posts: 123
Joined: Mon May 18, 2020 2:51 pm

Re: Weird behaviour on GPIO17 on WROOM32 module

Postby RichPiano » Thu Apr 29, 2021 5:52 am

Thanks for your reply! I'm using NodeMCU dev modules from JoyIT which all have WROOM32 modules attached. Also I'm using esp-idf. But the problem also appers when tested with Arduino IDE, so it doesn't seem to be specific to the platform.

ESP_Sprite
Posts: 9746
Joined: Thu Nov 26, 2015 4:08 am

Re: Weird behaviour on GPIO17 on WROOM32 module

Postby ESP_Sprite » Fri Apr 30, 2021 1:50 am

No idea... Can you perhaps try it on a different development board? It almost sounds like a bad solder joint or something.

RichPiano
Posts: 123
Joined: Mon May 18, 2020 2:51 pm

Re: Weird behaviour on GPIO17 on WROOM32 module

Postby RichPiano » Fri Apr 30, 2021 10:04 am

Hmm in essence we have already done that. We have soldered the standalone module to our own PCB but the problem persists even then.

I think we will just have to use different pins then :/

ESP_Sprite
Posts: 9746
Joined: Thu Nov 26, 2015 4:08 am

Re: Weird behaviour on GPIO17 on WROOM32 module

Postby ESP_Sprite » Thu May 06, 2021 3:14 am

Well, it could be a bad module somehow, hence me asking. Better to try with all-new hardware just to be sure, especially as there is no real known 'weird' behaviour for that IO pin on a Wrover32.

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