Innovative iBIT RACER, Активити-буклет

Страница: 35 / 92

Programmable robot with micro:bit 

35
3.1.7 Compass
The compass detects the earth’s magnetic
field, allowing you to detect which direction the
micro:bit is facing. The compass has to be calibrated
before it can be used.
‘Calibrating’ the compass ensures the
compass results are accurate. When the calibration
begins, the micro:bit will scroll an instruction on the
display for you - either “Draw a circle” or “Tilt to fill
screen”. To calibrate the compass, just follow these
instructions and tilt the micro:bit to move the dot in
the centre of the screen around until you have
either drawn the outline of a circle, or filled up the
whole screen.
The on-board compass sensor is NXP/Freescale
MAG3110 . Max update rate is 80Hz, Full scale range
is 1000  T and sensitivity is 0.10  T
Protocol : Nordic Gazell
Frequency band : 2.4GHz
Channel rate : 1Mbps or 2Mbps
Encryption : None
Channels : 101 (0..100)
Group codes : 255
Tx power : 8 user configurable settings
from 0 (-30dbm) to 7 (+4dbm)
Payload size : 32 (standard) to 255
3.1.8 Radio
The radio feature allows user to communicate
wirelessly between micro:bits. Use the radio to send
messages to other micro:bits, build multiplayer
games, and much more!
The on board 2.4GHz transciever supports a
number of other radio communications standards,
including the proprietary Nordic Gazell protocol. This
protocol provides a very simple small-packet
broadcast radio interface between other devices
that support this proprietary protocol, such as other
micro:bit devices. The ‘radio’ interface that appears
in a number of the languages on the micro:bit is built
on top of this Gazell protocol. Additionally, the
micro:bit runtime software adds a ‘group code’ to
each data payload, allowing for simple user
managed device addressing and filtering to take
place.