Let me take you on a tour of your Trinket! Each trinket is assembled here at Adafruit and comes chock-full of good design to make it a joy to use.

• Micro-B USB connector - We went with the ultra-common micro-B USB connector for power and/or USB bootloading. We use a special half SMT/half thru hole connector with extra big pads so the connector is very strong. It's also a proper USB connector, so you can use any length cable. Don't forget to use a data+power USB cable if you want to bootload! Some really inexpensive USB cables are 'power only'
• Green Power LED - you'll know that the board is powered up when this bright LED is lit
• Red #13 LED - this LED does double duty. Its connected with a series resistor to the digital #13 GPIO pin. It pulses or blinks nicely when the Pro Trinket is in bootloader mode, and its also handy for when you want an indicator LED.
• Battery + Input - take your Trinket anywhere and power it from an external battery. This pin can take up 16V DC input, and has reverse-polarity, over-curent and thermal protections. The circuitry inside will use either the battery or USB power, safely switching from one to the other. If both are connected, it will use whichever has the higher voltage
• USB Power Output - You can also snag the 5V power from the USB jack in case you need 500mA+ current from your computer or portable USB power pack.
• Breadboard friendly pins - You can easily plug this into a little breadboard and have plenty of space for working and plugging stuff in
• GPIO pins - 18 GPIO pins + 2 analog-only pins, at 3 or 5V logic, check the next section for a detailed pinout guide
• 3 or 5V output - an onboard regulator provides 3.3V or 5V output for powering LEDs, sensors, small motors, etc.
• Reset Button - an onboard reset button will launch the bootloader when pressed and the Trinket is plugged into a computer. If it is not connected to a computer, it's smart enough to go straight to the program.
• External Reset Pin - we bring out the reset pin so you can reset or restart your Trinket on the road. If the Trinket is in a box or otherwise hard to get to, you can wire up a button to this pin for an external reset button.
• Three mounting holes make it easy to attach with 2mm screws (M2 metric or #2 imperial) or even tiny zip-ties, string, etc.

On the bottom there's a spot for a 2-pin JST-PH connector. this is optional and can be soldered on by hand. It will let you use a lipoly or AAA battery pack or a JST cable for other power input. It's connected to the GND and VBAT pins