ESP32 Forum

I have recently come across an issue where I ran out of GPIO pins on an ESP32-C3FN4, as per the datasheet says, VDD_SPI pin can be used as GPIO11, However I am unsure If it would effect the power supply for the built-in flash, as there is no diagram on how the internal 4Mb of flash is being powered.

My question is:
How is the built-in flash powered on ESP32-C3FN4? Is it powered by VDD_SPI or VDD3P3_CPU?
Would It be safe to use VDD_SPI as GPIO11 on ESP32-C3FN4/ ESP32-C3FN4 and not having power issue when interfacing with built-in flash?

That is a good question. I'll ask the docs team to look into this and add it to the datasheet. If you can't wait for this, you could test this simply by taking an example program that is moderately complex (more complex than 'hello world') and adding a line that makes GPIO11 a low output at the beginning of app_main. If the program crashes, you can't use that GPIO.

Thanks for the reply! I would like to wait for an response from the docs team, as configuring VDD_SPI into GPIO11 involves changing an efuse bit, and once it's changed it cannot be reverted.

Good point; cheap as they are, throwing away a C3 over this is a shame. Note that as it's the Chinese new year week, you probably won't get an answer for one or two weeks, though.

Hi,

Really sorry for the late reply. By default VDD_SPI is the power supply pin for in-package flash or external flash. It can only be used as
GPIO11 when the chip is connected to an external flash, and this flash is powered by an external power supply. So in your case, please do not use VDD_SPI as GPIO11.

I will add this explanation to ESP32-C3 chip datasheet. Sorry for the inconvenience brought!