Are you looking for a microcontroller for your project and just need a few IO pins? Adafruit's Trinket Mini Microcontroller is the board for you. This tiny little board runs powerful ATTiny85 micro controller and has 8K of flash and 5 IO Pins. Just connect it to a computer via USB and use it as a mini Arduino board. Perfect for when you don't want to give up your expensive dev-board and you aren't willing to take apart the project you worked so hard to design. It's Adafruit's lowest-cost arduino-IDE programmable board!
The Adafruit Trinket comes in 2 variations, 5V and 3V logic. Both work the same, but have different operating logic voltages. Use the 3V one to interface with sensors and devices that need 3V logic, or when you want to power it off of a LiPo battery. The 3V version should only run at 8 MHz.
Use 5V Trinket for sensors and components that can use or require 5V logic. The 5V version can run at 8 MHz or at 16MHz by setting the software-set clock frequency.
Even though you can program Trinket using the Arduino IDE, it's not a fully 100% Arduino-compatible. There are some things you trade off for such a small and low cost microcontroller!
|Operating Voltage||3.3V DC|
|Input Voltage (Limits)||3 to 16V DC|
|Digital I/O Pins||4 (of which 2 provide PWM output)|
|Analog Input Pins||1|
|Flash Memory||8 KB (2.75 KB used by boot loader)|
|Clock Speed||8 MHz|
|USB||Mini USB for power or USB uploading|
|Power Supply||USB or external output (battery or power supply) - automatic switching|
|Dimensions||31 x 15.5 x 5 mm|