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Re: IO0 Internal Pullup Disabled?
Posted: Mon Mar 04, 2019 5:36 pm
by DurandA
This solved my issue, thanks. Out of curiosity, what is happening when the capacitor connected to the ENABLE pin is missing?
Re: IO0 Internal Pullup Disabled?
Posted: Mon Mar 04, 2019 11:45 pm
by Angus
As I understand it, the capacitor is intended to slow the rise of EN when power is applied. This means the chip boots slightly later after power is applied. This can be helpful in cases where VCC may be "soft start" or initially unstable.
Re: IO0 Internal Pullup Disabled?
Posted: Tue Mar 05, 2019 4:39 am
by Angus
If anyone has an ESP32 which doesn't work without an external IO0 pullup and is prepared to send their hardware back to us to investigate, please Private Message me here on the forum. We can compensate with replacement module(s).
Re: IO0 Internal Pullup Disabled?
Posted: Wed Dec 09, 2020 1:22 pm
by DrKnow65
If anyone has an ESP32 which doesn't work without an external IO0 pullup and is prepared to send their hardware back to us to investigate, please Private Message me here on the forum. We can compensate with replacement module(s).
I have a V3 ESP-WROVER-KIT that I have been getting the HSPI 0x1000 error with and have determined that the IO0 is not being pulled up internally, it is actually sinking at 365ohms. If I externally pull up with a 220ohm resistor the board boots properly. I would be happy to send this one back in trade for a working unit

I cannot PM yet as I only registered in order to respond to this post...
If you can contact me I will be happy to make arrangements.
Re: IO0 Internal Pullup Disabled?
Posted: Mon Dec 14, 2020 2:35 am
by Angus
Hi DrKnow65,
Thanks for the offer of exchanging this one. Just to confirm - did this WROVER-KIT have this problem from new, or is this something that appeared over time? This kind of internal short to ground can be caused by damage from ESD.
However if it came like this then we'd be very happy to exchange it in order to take a look.
Angus
Re: IO0 Internal Pullup Disabled?
Posted: Sun Dec 27, 2020 3:05 pm
by DrKnow65
The board has always had the fault, I added a resistor to R2 as a pull-up. The board seems to work well but the current draw is incorrect because there is essentially a pull-up fighting a pull-down perpetually.
Glad to trade it out with a fully functional dev board if it will do you some good. How do I coordinate getting this to you? I don't mind having it out of hand for a bit as I have several other wrover based dev boards to work with, they just lack the resources this board supplies but the project that uses a display is currently on a back burner...
If you are just being kind to offer to replace the board as a warranty offer I am not too put off by the power issue as the final product will be unique in layout anyway. If it's a curiosity for the quality control department I'm happy to send it in on my dime and wait for you to have it in hand before sending out the replacement. If it is convenient to send the S2 version I wouldn't be upset

Re: IO0 Internal Pullup Disabled?
Posted: Mon Dec 28, 2020 11:52 pm
by Angus
Hi DrKnow,
Thanks for the update. We're keen to take a look at this module.
I've passed your forum email address to a colleague in the Shanghai office, someone should be in touch soon to arrange return and replacement.
Angus
EDIT: Have edited first post to place our internal ID for tracking.
Re: IO0 Internal Pullup Disabled? [IDFGH-4504]
Posted: Fri Jan 02, 2026 8:48 am
by giulioto
Hi, I had the same problem with the ESP32-WROOM-32UE-N8 in two projects. In the first prototypes, I managed to add a 10kΩ pullup resistor to IO0, but in subsequent projects I added the same resistor directly into the project, since I have no way of knowing if the ESP32 uP has the problem or not. Is this the right approach?
Thanks
giulio