ESP32 PoE IoT Board changed schematic

[Xyven]

Hey,
I recently purchased some of these dev boards, but my boards do not match the schematic or pictures online. The only difference I notice is that the bottom set of pins on the ESP32 chip have been exposed via surface mount contacts on the board, which includes GPIO 6-11.


Why would these pins be exposed if they cannot be used, as they are connected to the integrated SPI flash? The latest schematic on github states "GPIO6 to GPIO11 are connected to the SPI flash integrated on the module and are not led out!", but they clearly are. Is this a difference between esp32 chip versions (WROOM vs WROVER) or is there some other reason these pins are exposed? 
The crux of the question is: can I use these pins as GPIO (I have completely run out of GPIO that don't have weird side-effects like GPIO0), or are they actually connected the integrated flash?

[LubOlimex]

I am not sure if I understand the question. GPIO6-GPIO11 are unavailable and not lead out, and even if you solder directly to the WROOM chip legs you can't use these pins. They are used for the internal memory of the ESP32 module.

You should use the pins available at EXT1, EXT2, and UEXT connectors. Also if you are not using SD card, you can use the pins of the SD card (GPIO2, GPIO14, GPIO15). Also by default battery measurement and sense are disabled and if you don't use those you can also use GPI35 and GPI39. If that is insufficient consider adding some board that can multiply the GPIOs over I2C or SPI like MOD-IO2:

https://www.olimex.com/Products/Modules/IO/MOD-IO2/open-source-hardware

> Why would these pins be exposed if they cannot be used, as they are connected to the integrated SPI flash?

I believe they had never been exposed to GPIOs in ESP32-POE design. Like they had never been available on the EXT headers at all.

But one can lead them out for completeness and for hardware debugging purposes. They can be used to connect voltage and ampere meters or oscilloscopes and measure levels.

[JohnS]

"Led out" for a board design would mean "led out to pins/headers (or other connectors) and available for use".

They may still be connected somewhere else, but are not available for general use.

John

[Xyven]

Ah, ok, so those surface mount points are for debugging. That makes sense. I guess I am out of luck in terms of running out of pins. I am using all the pins you mentioned LubOlimex, except 39, but I don't think that one extra will cut it in my case.

IMHO, this documentation is not clear that pin 39 is free, as it simply states it is used.

[LubOlimex]

I believe it is leftover from older revisions, in older hardware revisions battery measurement was enabled by default but in latest revisions we decided to keep the jumpers open, so only people that need battery sense and measurement would close them. The rest of customers can use these pins as GPIOs. Speaking of which notice that GPI39 can't be output as per specification of the chip, it is not a typo "GPI39" can only be input regarding the ESP32 board.

[Xyven]

Ah, that makes some sense. It's a bummer the other 10 or so full GPIO pins that the esp32 has aren't exposed. Is there a reason for this? Are they being used for some other features on the board? Or is it just a question of real estate?

[LubOlimex]

We have lead all pins that are usable. Pins that had not been exposed are unusable. If you wish to study why take a look at the specification for the ESP32-WROOM-32E module

https://www.espressif.com/en/content/esp32-wroom-32e-esp32-wroom-32ue-datahseet

So if you explore the document stop on page 11 and 12 and notice the footnote:

"Pins GPIO6 to GPIO11 on the ESP32-D0WD-V3/ESP32-D0WDR2-V3 chip are connected to the SPI flash integrated on the module and are not led out."

[Xyven]

I understand that, I am talking about these pins:

Are these not exposed for some reason?

[LubOlimex]

These are all connected and routed.

GPIO # 12, 17, 18, 19, 21, 22, 23, 25, 26, 27 are used for the Ethernet chip. Here:





If you don't need wired Ethernet you can use a board without such and these will be free. Like ESP32-DevKit-LiPo.

https://www.olimex.com/Products/IoT/ESP32/ESP32-DevKit-LiPo/open-source-hardware

[Xyven]

Ah, thank you very much, that is what I figured, but I wasn't sure. I appreciate the help.