The center of the board is home to the ATSAMD21E18 microcontroller. It is a 32-bit Cortex M0+ processor at 48 MHz with 256KB Flash and 32 KB RAM. The SAMD21 has native USB supported by every OS. It can be used in Arduino or CircuitPython as USB serial console, MIDI, Keyboard/Mouse HID, even a little disk drive for storing Python scripts.

On one end of the Pixel Trinkey is the USB connector. Plug it into any USB A port on your laptop or computer, NeoPixel-and-terminal-block-side-up.

At the end of the board, across from the USB port, is the terminal block. This terminal block has connections for connecting NeoPixel or DotStar LEDs with no soldering, just a screwdriver.

• - - common ground
• D - The data pin for the LEDs. Accessed in CircuitPython with board.DATA and Arduino with PIN_DATA or 4.
• C - The clock pin for the LEDs, required for DotStar LEDs. Accessed in CircuitPython with board.CLOCK and Arduino with PIN_CLOCK or 5.
• + - 5V VBUS power output

On the top edge of the board, between the reset button and terminal block, is a 3-pin JST SH connector. This port is helpful if you want to add additional circuitry, such as an Infrared remote input, potentiometer, or a button. Use a JST SH 3-pin cable to access 3V, ground and GPIO pin D4. This pin can be accessed in CircuitPython with board.D4 and Arduino with 6, MISO or PIN_MISO.

On the edge of the board, behind the terminal block and across from the JST SH connector, is one RGB NeoPixel LED. This LED is controllable in CircuitPython using board.NeoPixel and Arduino using PIN_NEOPIXEL or 1. 

Towards the center of the board, above the microcontroller, is the reset button.

Tap once to reset the board. Tap twice to enter the bootloader (needed for installing CircuitPython).

On the back of the board are three pads that can be used for JTAG debugging. They are, from left to right:

• SWDIO - The data pin, farthest from the USB port.
• SWCLK - The clock pin, the middle pin.
• RESET - The reset pin, closest to the USB port.