This describes the micro:bit V2, which is distinguished from the V1 by a distinct set of notches in the bottom long edge. Components are described relative to the locations of other parts.


Orientation and front face of the micro:bit

The micro:bit is held in landscape orientation, with five notches along the bottom edge and some connectors (USB and power) mounted along the top edge. The front face forms the main user interface of the micro:bit. It has two push-buttons mounted on the face, on the left hand side (button A) and the right hand side (button B). Programs can be written to perform different actions when these buttons are pressed.  

Between the 2 buttons is a uniform grid of small LEDs, which forms the 5x5 pixel display. These form a regular grid about 1.5cm square.
In the middle of the front face, just above the LED grid there is a touch sensor, which is surface printed and hard to detect. This can be used by programs as an additional input. The microphone hole and microphone LED are just to the right of the touch sensor, above the rightmost column of LEDs.
Along the bottom edge of the board, each notch locates a ring pin, where you can connect accessories using a crocodile clip. From left to right (facing the front of the board) the pins are: pin 0, pin 1, pin 2, 3V power and ground. About 0.5cm above each notch there is a hole, which can be used for banana plug connections. You can find the holes by poking with a cocktail stick, or by squeezing the front and back faces between a finger and thumb.
In addition to the main ring pins, there are intermediate pins available which are only useable by adding an edge connector to break out each additional pin. These can be identified as thin surface mounted strips between each main ring pin and are described in more detail further down this page.


Rear face of the micro:bit + connectors

The rear face of the micro:bit is where most of the components are mounted.  Along the top edge there are two connectors. Right in the centre is a micro-USB port, for connecting to a computer. Either side of it are two small status LEDs. On the left a red LED shows the power status and on the right a yellow LED indicates USB activity.
To the right of the USB connector is a push button which is the reset button, and then a JST connector for plugging in a battery. To remove a JST cable, use your fingernails and some gentle wiggling.
Other components of interest are generally smooth rectangles, either plastic or metal. The most obvious component is the speaker, which is the largest smooth plastic component approximately in the centre of the board. It is shaped like a diamond, with corners cut off slightly. To the right of the speaker is the USB interface chip.
To the left of the speaker, and slightly up is a the processor (Nordic nRF52833), which is a much flatter plastic diamond shape. The processor is the brains of the micro:bit, and is where user programs are run. Diagonally up and right of the processor, the microphone is a small smooth metal component with rounded edges, half way between the processor and the microUSB port. Up and left from the processor is a surface-printed antenna for bluetooth connectivity. This is hard to detect, but takes up the smooth space 1.5 cm in from the corner on each edge.
The compass and accelerometer are housed in a very small square component at about 7 o'clock from the processor, forming a triangle with the holes for the leftmost 2 pins.


Edge connector

The edge connector along the bottom edge of the micro:bit is used to connect to external circuits and components.

There are 25 strips/pins including 5 rings for using with 4mm banana plugs or crocodile clips. The rings can be identified by a notch along the bottom edge, and a corresponding hole in the board about 0.5cm in from the edge. The first 3 rings from the left (while looking at the front of the board) are for general purpose input and output (GPIO) and are also capable of analog, PWM and touch sensing. The last two pins are connected to the micro:bit power supply, 3 volt and ground.

The smaller strips spaced at 1.27mm on the edge connector have additional signals, some of which are used by the micro:bit, and others that are free for you to use. There are a number of external PCB connectors for purchase with an 80w 1.27mm pitch that can be used to easily access these extra pins.

Only the pins on the front are connected to signals. The back rings are connected to the front rings, but the back small strips are unconnected.

From left to right (looking at the front of the micro:bit where buttons A, B and the LED display are), the pins are as follows. Note that the pin numbering is based on the main accessible rings being P0 to P2 before interleaving higher pin numbers starting from the left hand side:

  • Pin 3 | LED Column  3 | ANALOG IN
  • Pin 0 (ring) | ANALOG IN
  • Pin 4 | LED Column 1 | ANALOG IN
  • Pin 5 | Button A
  • Pin 6 | LED Column 4
  • Pin 7 | LED Column 2
  • Pin 1 (ring) | ANALOG IN
  • Pin 8 
  • Pin 9 
  • Pin 10 | LED Column 5 | ANALOG IN
  • Pin 10 | Button B
  • Pin 12 | Reserved for accessibility
  • Pin 2 (ring) | ANALOG IN
  • Pin 13 | SPI1 SCK
  • Pin 14 | SPI1 MISO
  • Pin 15 | SPI1 MOSI
  • Pin 16
  • 3v3+
  • 3v3+ (ring)
  • 3v3+
  • Pin 19 | I2C1 SCL
  • Pin 20 | I2C1 SDA
  • GND
  • GND (ring)
  • GND

For even more technical details in various formats, see pins and signals on tech.microbit.org