How to Use GEMMA v1: Examples, Pinouts, and Specs

The GEMMA v1 is a miniature wearable electronic platform powered by the ATtiny85 microcontroller. It is designed by Adafruit for small-scale projects where size and power efficiency are crucial. The GEMMA v1 is ideal for wearables, e-textiles, and IoT applications due to its tiny footprint and versatile I/O options.

• Wearable electronics (e.g., smart clothing, accessories)
• Interactive textile projects
• Small robotics
• Educational purposes for learning electronics and programming
• Prototyping IoT devices

• Microcontroller: ATtiny85
• Operating Voltage: 3.3V
• Input Voltage: 4-16V (via battery port)
• Digital I/O Pins: 3 (of which 2 are PWM capable)
• Analog Input Pins: 1 (shared with digital I/O)
• Flash Memory: 8 KB (ATtiny85) of which 2.75 KB used by bootloader
• SRAM: 512 bytes
• EEPROM: 512 bytes
• Clock Speed: 8 MHz
• Dimensions: 28mm diameter

1. Powering the GEMMA v1:

   • Connect a battery to the BAT and GND pins for portable applications.
   • Ensure the battery voltage is within the 4-16V range.

2. Programming the GEMMA v1:

   • Use the USB interface and a compatible IDE (e.g., Arduino IDE) to upload sketches.
   • Select the board type as "Adafruit GEMMA" in the IDE.

3. Connecting I/O:

   • Use the digital I/O pins to connect LEDs, sensors, and other components.
   • For analog input, use the A1/D2 pin.

4. Using PWM:

   • Pins A2/D0 and A3/D1 support Pulse Width Modulation (PWM) for controlling devices like servo motors or dimming LEDs.

• Always disconnect the battery or power source before making or altering connections.
• Be mindful of the power requirements of connected peripherals to avoid overloading the GEMMA v1.
• Use appropriate resistors when connecting LEDs to limit current and prevent damage.
• Avoid exposing the board to conductive materials that could cause shorts.

• GEMMA v1 not recognized by computer:

  • Ensure the USB cable is properly connected and the computer's USB port is functioning.
  • Try using a different USB cable or port.

• Sketch upload fails:

  • Check that the correct board and port are selected in the IDE.
  • Press the reset button on the GEMMA v1 just before uploading.

• Connected peripherals not working:

  • Verify connections and ensure that the peripherals are compatible with the GEMMA v1's voltage and current specifications.
  • Check for any loose connections or solder joints.

• If the GEMMA v1 is not functioning as expected, double-check all connections and ensure that the power supply is within the specified range.
• Consult the Adafruit forums and guides for additional support and community-driven solutions.

// Blink an LED connected to pin D1 of the GEMMA v1

#define LED_PIN 1 // Define the pin the LED is connected to

void setup() {
  pinMode(LED_PIN, OUTPUT); // Set the LED pin as an output
}

void loop() {
  digitalWrite(LED_PIN, HIGH); // Turn the LED on
  delay(1000);                // Wait for a second
  digitalWrite(LED_PIN, LOW);  // Turn the LED off
  delay(1000);                // Wait for a second
}

Note: This code is for demonstration purposes and assumes an LED with an appropriate resistor is connected to pin D1 of the GEMMA v1. Always ensure that your circuit is designed according to the component's specifications.