Datasheet

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!

Analog Pins

There is also a single analog input pin called A. This pin has a ~1.0V maximum voltage, so if you have an analog

voltage you want to read that is higher, it will have to be divided down to 0 - 1.0V range