ESP8266 Community Forum

I'm not intimately familiar with the Xtensa architecture. Might there be some way in the future to have additional ADC inputs with the appropriate SDK and firmware changes? I was thinking about designing a small board which would accept an ESP-12 and would also have an analog mux like a 74LV4051 (8 inputs) or a TI TS5A3357 (3 inputs). I won't bother if there's a chance we might be able to reconfigure GPIO through firmware soon...

Of course, that should be simple ! But that doesn't require anything to be added to current SDK, it is purely on the side of user_app.
If the sampling rate is not an issue, I would suggest to put the 4051 addressing on a GPIO extender such as MCP23017, it is an I2C chip that can be controlled from the ESP8266 using only 2 of its GPIOs, providing new 16 GPIOs, where only 3 is needed to be hoookup to the 4051, the remaining can be used for any other ideas we can have ...

If you add an i2c device i would add an ii2c adc with multiple inputs. That would possible solve thr issue of sampling only when the wifi is down.

Dunno if rf interfere with all adc though.