Datasheet

This is the general purpose I/O pin set for the microcontroller. All logic is 3.3V

#0 / RX - GPIO #0, also receive (input) pin for Serial1 and Interrupt #2

#1 / TX - GPIO #1, also transmit (output) pin for Serial1 and Interrupt #3

#2 / SDA - GPIO #2, also the I2C (Wire) data pin. There's no pull up on this pin by default so when using with I2C,

you may need a 2.2K-10K pullup. Also Interrupt #1

#3 / SCL - GPIO #3, also the I2C (Wire) clock pin. There's no pull up on this pin by default so when using with I2C,

you may need a 2.2K-10K pullup. Can also do PWM output and act as Interrupt #0.

#5 - GPIO #5, can also do PWM output

#6 - GPIO #6, can also do PWM output and analog input A7

#9 - GPIO #9, also analog input A9 and can do PWM output. This analog input is connected to a voltage divider

for the lipoly battery so be aware that this pin naturally 'sits' at around 2VDC due to the resistor divider

#10 - GPIO #10, also analog input A10 and can do PWM output.

#11 - GPIO #11, can do PWM output.

#12 - GPIO #12, also analog input A11 and can do PWM output.

#13 - GPIO #13, can do PWM output and is connected to the red LED next to the USB jack

A0 thru A5 - These are each analog input as well as digital I/O pins.

SCK/MOSI/MISO - These are the hardware SPI pins, used by the RFM radio module too! You can use them as

everyday GPIO pins if you don't activate the radio and keep the RFM CS pin high. However, we really

recommend keeping them free as they should be kept available for the radio module. If they are used, make sure

its with a device that will kindly share the SPI bus! Also used to reprogram the chip with an AVR programmer if

you need.

RFM/SemTech Radio Module

https://learn.adafruit.com/adafruit-feather-32u4-radio-with-rfm69hcw-

module

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