Adafruit Pro Trinket - 5V 16MHz
➤ ATmega328P onboad chip in QFN package
➤ 16MHz clock rate, 28K FLASH available
➤ USB bootloader with a nice LED indicator looks just like a USBtinyISP so you can program it with AVRdude and/or the Arduino IDE (with a few simple config modifications).
➤ Also has headers for an FTDI port for reprogramming
➤ Micro-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.
➤ On-board 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 #13 LED
➤ Reset button for entering the bootloader or restarting the program.
➤ Works with 99% of existing Arduino sketches (anything that doesn't use more than 28K, and doesn't require pins #2 and #7)
➤ Mounting holes
➤ 38mm x 18mm x 2mm / 1.5" x 0.7" x 0.08"
➤ Height with MicroUSB: 4mm / 0.16"
➤ Weight: 2.6g