GPIO2 Anomaly

[Airhead]

I have found that a sketch (Arduino IDE) will not Upload with an LED between +3V and GPIO2.
It's OK with an LED between +3 and GPIO4 though.

"A fatal error occurred: Failed to connect to ESP32: Timed out waiting for packet header

If it's a red LED then it bombs; if it's a yellow LED then it's OK.

(Red has a 240Ω resistor, Yellow has 270Ω resistor).

[Airhead]

OK, I found the answer - in the Espressif datasheet.
GPIO2 is a "strapping pin" and its condition determines the boot state.
(GPIO5 is a "strapping pin", too.)

It's all there in 2.4
https://www.espressif.com/sites/default ... eet_en.pdf