Adafruit Feather HUZZAH ESP8266, Руководство пользователя

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GPIO pins
This breakout has 9 GPIO: #0, #2, #4, #5, #12, #13, #14, #15, #16 arranged at the top
edge of the Feather PCB
All GPIO are 3.3V logic level in and out, and are not 5V compatible. Read the full
spec sheet (https://adafru.it/f1E) to learn more about the GPIO pin limits, but be aware
the maximum current drawn per pin is 12mA.
These pins are general purpose and can be used for any sort of input or output. Most
also have the ability to turn on an internal pullup. Many have special functionality:
GPIO #0, which does not have an internal pullup, and is also connected a red LED.
This pin is used by the ESP8266 to determine when to boot into the bootloader. If the
pin is held low during power-up it will start bootloading! That said, you can always use
it as an output, and blink the red LED - note the LED is reverse wired so setting the
pin LOW will turn the LED on.
GPIO #2, is also used to detect boot-mode. It also is connected to the blue LED that is
near the WiFi antenna. It has a pullup resistor connected to it, and you can use it as
any output (like #0) and blink the blue LED.
GPIO #15, is also used to detect boot-mode. It has a pulldown resistor connected to it,
make sure this pin isn't pulled high on startup. You can always just use it as an output
GPIO #16 can be used to wake up out of deep-sleep mode, you'll need to connect it
to the RESET pin
Also note that GPIO #12/13/14 are the same as the SCK/MOSI/MISO 'SPI' pins!
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