Let me take you on a tour of your Gemma M0! Each Gemma M0 is assembled here at Adafruit and comes chock-full of good design to make it a joy to use.

  • Micro B USB connector - We went with the tried and true micro-B USB connector for power and/or USB communication (bootloader, serial, HID, etc). Use with any computer with a standard data/sync cable.
  • RGB DotStar LED - Instead of an always-on green LED we provide a full RGB LED. You can set it to any color in the rainbow. It will also help you know when the bootloader is running (it will turn green) or if it failed to initialize USB when connected to a computer (it will turn red). By default after you boot up the Gemma M0 it will turn a lovely violet color.
  • Red #13 LED - this LED does double duty. Its connected with a series resistor to the digital #13 GPIO pin. It pulses nicely when the Gemma is in bootloader mode, and its also handy for when you want an indicator LED.
  • JST Battery Input - take your Gemma anywhere and power it from an external battery. This pin can take up 6V DC input, and has reverse-polarity, over-current and thermal protections. The circuitry inside will use either the battery or USB power, safely switching from one to the other. If both are connected, it will use whichever has the higher voltage. Works great with a Lithium Polymer battery or our 3xAAA battery packs with a JST connector on the end. There is no built in battery charging (so that you can use Alkaline or Lithium batteries safely)
  • Vout (Voltage Output) - This pin will give you either the battery power or USB power, whichever has a higher voltage. Its great when you want to power something like NeoPixels, that might use more than the 500mA available from the onboard regulator
  • 3V Regulator - The on-board voltage regulator can supply up to 500mA at a steady 3.3V from up to 6VDC
  • Sewing and Alligator clip friendly pads - You can easily sew to these pads, and they're gold plated so they wont corrode (oxidize). You can also use alligator clips or solder directly to them.
  • 3 General Purpose I/O (GPIO) Pads! - 3 GPIO pins, at 3V logic, check the next section for a detailed pinout guide
  • Reset Button - an onboard reset button will launch the bootloader when pressed and the Gemma is plugged into a computer. If it is not connected to a computer, it's smart enough to go straight to the program.
  • On/Off switch - Lets you turn on/off your project, it will control both the Gemma and the Vout pad. This switch can switch up to about 500mA of current, so if you are driving a huge number of servos or NeoPixels, connect power to those power-greedy parts externally.

This guide was first published on Jul 26, 2017. It was last updated on Jun 11, 2024.

This page (Guided Tour) was last updated on Jul 26, 2017.

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