Inside the Micro:bit¶
Microcontroller¶
The micro:bit contains an ARM 32-bit microcontroller with 128kB flash memory and 16kB RAM memory; While this is a fraction of what is available in computers and smartphones, it is enough for most of the tasks the micro:bit has been designed for, such as reading from sensors or controlling digital outputs.
Power¶
The micro:bit works internally at 3.3v. It can be powered with the USB cable thanks to an on-board regulator, and in alternative two AA Batteries can be used.
Lipo 3.7v batteries require a step-down circuit, or you risk to burn the Micro:bit when the battery is fully charged.
LEDs¶
Micro:bit LEDs are red color only. The form a 5 × 5 matrix. The brightness of the set of LEDs as a whole can also be controlled.
Coordinates start at (0,0) in top left-hand corner. In computing, displays start at the top left-hand corner so, in coding terms, this is (0,0). This is different from mathematics and graphs where (0,0) is the bottom left corner. It is important to note this is also relative, so if the screen rotates (0,0) is still the top left corner of the screen.
Buttons¶
The board includes two push-buttons, named A and B.
The micro:bit detects when these button are being pressed. This is a push-to-make switch (pressing it completes an electrical circuit).
There’s also a Reset Button, allowing us to program the micro:bit wirelessly and to restart the program execution.
Accelerometer¶
Converts analogue information about how quickly the micro:bit’s speed changes to a digital form that can be used in programs. Output from the accelerometer is in milli-g. The accelerometer allows the micro:bit to be used to control movement of on-screen characters, etc.
Compass (Magnetometer)¶
A sensor to detect magnetic fields, like the Earth’s, allowing the direction of the micro:bit to be determined and converted to a digital form that can be used in programs. Output from the compass is degrees.
Radio¶
The micro:bit includes a Bluetooth Low Energy (BLE 4.0) radio, that can be used to communicate to any device supporting such protocol (smartphones, tables, PCs).
The Bluetooth Low Energy protocol allows to send small data packages (i.e. 32bits) at a low speed, but with very little power consumption. This protocol has been designed to transmit sensor data or to perform simple communication of small bits of data.
The same hardware can be also used to have many micro:bits communicating with each other using broadcast messages. In this case the protocol used is proprietary and limited to micro:bits.
It’s possible to select different channels and to limit communication to groups of devices.
USB port¶
The USB port on the micro:bit can be used for different purposes.
The first is to connect the PC and use the USB to transfer the firmware hex files.
The second is to use it as a Serial port, so that you can write your code on a serial console or interact with the Micro:bit sketches.