ESP32 Forum

Hi all,
The espefuse output contains a line:
Flash voltage (VDD_SDIO) determined by GPIO12 on reset (High for 1.8V, Low/NC for 3.3V)
I read somewhere that the onboard flash of WROVER modules runs on 1.8V.
My question: is it possible to destroy the on-board flash by a low signal on GPIO12 during booting?
Thanks!

nkronert wrote: ↑

Sun Jul 09, 2023 11:09 pm

I read somewhere that the onboard flash of WROVER modules runs on 1.8V.

That depends on the particular type of WROVER boards. I think the first ones used 1.8V flash/psram exclusively, but later ones switched to 3.3V parts. Read the datasheet of your particular one to find out what it is.

My question: is it possible to destroy the on-board flash by a low signal on GPIO12 during booting?

Generally, a wrong signal on GPIO12 means the chips are ran out of their absolute maximum ratings, which could mean they get damaged in some way, shape or form, yes. (In practice, these chips do seem to survive for a fair while when you accidentally run them on the wrong voltage, however, although we obviously do not recommend this.)

Thank you kindly for the quick reply.
I was asking because I got a number of boards from a friend (I assume he got them from Aliexpress) and the programming fails on all of them right out of the antistatic bag with the infamous

Configuring flash size...
Warning: Could not auto-detect Flash size (FlashID=0x0, SizeID=0x0), defaulting to 4MB
...
A fatal error occurred: Timed out waiting for packet header

On serial monitor:
rst:0x10 (RTCWDT_RTC_RESET),boot:0x33 (SPI_FAST_FLASH_BOOT)
flash read err, 1000
ets_main.c 371

I have tried all the tricks suggested in the forums like connecting a capacitor between EN and GND and such, to no avail.

I would hope that the MCU bootloader knows that it has a 1.8V flash on board and not allow 3.3V to be applied to it when GPIO12 is low or NOT CONNECTED at reset, as the latter is the case when the module is powered through USB without anything attached.

I'm assuming there is no way to recover these boards if indeed the flash has died?

In my experience, having 3.3V on the 1.8V part doesn't really do damage that fast; I'd certainly do not expect a whole heap of them to have failed right out of the box. (Aside from that, if you tell me what module is on it, I can check if it has a 3.3V flash in there, if that's the case a wrong GPIO12 level is highly unlikely to damage them). I'd think that it's more likely that the design of the modules is faulty in some way, causing them all to be dead.

Thank you for your reply, ESP_Sprite.
I realize that moderators may flag this post as slightly off-topic with regards to the question in the thread title, but I'd like to share my further findings.
I decided to remove the metal shield from one of the faulty modules because I found a post on internet that someone had a faulty soldering of the flash chip on his module.
Lo and behold, after resoldering the flash chip, I was able to program the module!
So luckily the flash chip wasn't damaged.
4 More modules to go, hopefully with the same positive outcome.

Nah, your post is pretty on-topic and it may help others who run into parts from the same batch of seemingly faulty devboards. Thanks for updating!