How to Program Adafruit Gemma V2

Introduction: How to Program Adafruit Gemma V2

About: My name is Bay Yolal, hello everybody!

Today, I am going to show you a very quick method to upload the blinking LED program to Adafruit Gemma v2(This has got micro USB slot). I wanted to write this instruction because I think we as a new developers need a very quick and express coding expressions to understand what is going on :)

The Need List:

1. Adafruit Gemma v2 (v2 has got micro USB slot to differ from v1. Gemma v1 has mini USB slot and without on/off button which is attached on v2) (I focused on Adafruit Gemma v2 on this instruction.)

2. Micro USB cable

3. Your PC (loaded Arduino IDE)

Step 1: Connections

Adafruit Gemma v2's micro USB slot is attached directly to your computer's USB slot via micro USB cable.

Step 2: The Blink Code

Copy these codes and paste it to your Arduino IDE program. These codes are blinking your onboard red LED working for 2 seconds, rest for 1 second.

void setup() {

	pinMode(1, OUTPUT);  

void loop() {     

digitalWrite(1, HIGH);     delay(2000);     

digitalWrite(1, LOW);      delay(1000); 


Note: If you need a driver of Adafruit Gemma, please download .rar file below. Than update your driver. (By the way, when you plug in Gemma to your PC you will see this board is called Trinket! Surprise! I repeat, don't care. :)

Step 3: Arduino IDE Settings

  1. Download and/or update your Arduino code uploading program which is newly announced as arduino.exe for Windows from here
  2. Tools >> Board >> Arduino Gemma
  3. Tools >> Programmer >> USBtinyISP

Don't care: COM port is don't care statement for us while we use Gemma because Gemma's Serial Port structure is not defined. So, don't need to select Port with COM numbers. If you see any COM name, just don't care and ignore.

Note: You may deactivate your Bluetooth while you are working with Arduinos or whatever.

Now, you are ready to upload codes.

  1. On Arduino IDE, write your codes
  2. On Adafruit Gemma, press the button which is located between green LED and red LED on the board.
  3. You will see 25-times red LED blinking this means that Gemma is now listening your code uploading session, and you must pressed upload icon on Arduino IDE in between this duration.
  4. That's it!

Step 4: Frequently Asked Questions

Q1: If there is an error you faced liked that:

avrdude: error: usbtiny_transmit:

A1: You forgot to press the black button on Adafruit Gemma v2 board. the board must be listen you with this button. The button is on between red smd LED and green smd LED.

Q2: If there is an error you faced liked that:

avrdude: initialization failed, rc=-1 Double check connections and try again, or use -F to override this check.

avrdude: error: usbtiny_transmit:

A2: (Check answer 1)This means, don't forget to press code uploading button.


That's all !

Step 5: BONUS: Reading This Instructable

NOTE: This instructable's step is aimed for visually impaired people to hear the sentences to learn what's going on here. Watch the video, it explains all steps.

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