GEMMA is a tiny wearable platform board with a lot of might in a 1″ diameter package. Powered by an Attiny85 and programmable with an Arduino IDE over USB, you’ll be able to realise any wearable project!
The Attiny85 is a fun processor because despite being so small, it has 8K of flash, and 5 I/O pins, including analog inputs and PWM ‘analog’ outputs. Adafruit have designed a USB bootloader so you can plug it into any computer and reprogram it over a USB port just like an Arduino (it uses 2 of the 5 I/O pins, leaving you with 3). In fact they even made some simple modifications to the Arduino IDE so that it works like a mini-Flora.
Even though you can program GEMMA using the Arduino IDE, it’s not a fully 100% Arduino-compatible board. There are some things you trade off for such a small and low cost microcontroller!
- GEMMA does not have a Serial port connection for debugging so the serial port monitor will not be able to send/receive data
- Some computers’ USB v3 ports don’t recognise the GEMMAs bootloader. Simply use a USB v2 port or a USB hub in between
- We do not have full Windows 8 driver compatibility tested. At this time we only have it working with Mac, Linux or Windows 7/XP
Here are some useful specifications!
- Super small, only 1.1″ / 28mm diameter and 0.28″ / 7mm thick.
- Easy-to-sew or solder pads for embedding in your wearable project
- Low cost enough, you can use one for every weekend project
- ATtiny85 on-board, 8K of flash, 512 byte of SRAM, 512 bytes of EEPROM
- Internal oscillator runs at 8MHz
- Ultra low power, draws only 9 mA while running
- USB bootloader with a nice LED indicator looks just like a USBtinyISP so you can program it with the Arduino IDE (with a few simple config modifications)
- Mini-USB jack for power and/or USB uploading, you can put it in a box or tape it up and use any USB cable for when you want to reprogram.
- We really worked hard on the bootloader process to make it rugged and foolproof
- ~5.25K bytes available for use (2.75K taken for the bootloader)
- On-board 3.3V or 5.0V power regulator with 150mA output capability and ultra-low dropout. Up to 16V input, reverse-polarity protection, thermal and current-limit protection.
- Power with either USB or external output (such as a battery) – it’ll automatically switch over
- On-board green power LED and red pin #1 LED
- Reset button for entering the bootloader or restarting the program.
- 3 GPIO – The 3 independent IO pins have 1 analog input and 2 PWM output as well.
- Hardware I2C capability for breakout & sensor interfacing.
For more information about GEMMA, check out Adafruit’s Learn guide.