Integration of new radio mode that permits simple local area multicast communication
directly between micro:bits using the device's on board radio hardware.
It should be noted that this implementation build directly on the nrf51822
hardware. It is not a BLE protocol, and must (currently) be operated with BLE
A standard on the wire configuration is defined, to promote future
interoperability between projects and languages. A lightweight
packet format is also defined and adhered to, so as to promote future
extensibility without sacrificing compatibility. The notion of groups is also
introduced, that enable multiple groups of children to work in the same area
without compromising each other's projects.
In adition to a low level packet radio driver, two higher level protocols are
defined that allow simple user datagram communication between micro:bits and
an EventBus protocol that allows the micro:bit's MessageBus to be extended to
The Nordic BLE stack contains a fixed size bond table - a list of devices that
have paired with our device (in the case the micro:bit). The default mbed
wrapper around the nordic stack does not account for the case where the bond
table is full.
This patch implements basic bounds checking within the MicroBitBLEManager so
that this table cannot overrun. If a new device attempts to pair when the bond
table is full, the table is emptied prior to completing bonding.
Added configuration option in MicroBitConfig to allow the default power level
to be defined. Based on experiments undertaken by the BBC and subsequent policies defined by
the BBC's child protection panel, to is set by default it's lowest level (0),
in order to protect children's privacy.
It should be noted that this is 30dB below the device's default setting, so will
inevitably leave the device more susceptible to interference, and therefore
significantly reduce the reliability of the device. This will likely present
itself through increased packet loss, reduced thorughout, lost data and
connection drop outs. The normal BLE power level on commercial devices
translates to power level of 6.
The author has witnessed an inability to connect to a micro:bit from a
distance of 40cm under domestic conditions using a Samsung S5 mini
running Android 4.4.2.
issue #73 highlighted an issue whereby the destruction of an instance
registered as an idle or system component, would result in a hardfault.
This was due to not deregistering idle or system callbacks.
This patch has been applied to all components currently in use by the
idle or system callbacks.
The destructor for MicroBitButton didn't take into account the fact that
an instance can be destructed after registering a callback. This would then
result in a HardFault if an instance was destructed.
A clear repro case was registering a Touch input on a pin (abstracted as a button)
and swapping to a DigitalIn.
* Added a number of #defines to MicroBitPin.h which ultimately lead to retabulation of the #defines
* Added two new instance methods:
- setServoValue() which sets the default servo period (20ms) and accepts a value in the range
0 - 180, which maps to a duty cycle between 5% and 10% respectively. This
mapping is also configurable.
- setServoPulseUs() which accepts a pulse width in microseconds, and maps it onto the PWM
Based on the previous commit, the api for MicroBitPin
has two new accessor methods:
There are also whitespace changes in the MicroBitPin head file
as well as some minor textual changes.
This commit introduces an initial draft fix
for a bug where it would take two "setPeriods" for the
PWM class to update to the expected value.
This commit also adds three new methods to a DynamicPwm instance:
* write() - which is a lightweight wrapper around PwmOut write,
so that the value can be trapped. The trapping of the value
is necessary for the bug fix.
* getPeriod() - which returns the value of a static variable,
containing the current period shared across the pwm bus.
* getValue() - which returns a scaled value in the range 0-1024
representing the current duty cycle.
Events listed recorded in MESEvents.h were enumerated from zero.
This is not ideal, as MicroBitMessageBus uses a code of zero for
MICROBIT_EVT_ANY - a wildcard mechanism to register interest in all events
from a given ID.
All event values recorded in MESEvents.h have therefore incremented.
Added missing operator new wrapper in MicroBitHeapAllocator.h
Ammended defualt microBitConfig.h to allocate 90% of available heap, rather
than 95%. this is to leave a little more heap for external libraries.
native printf() call.
The Matrix4::print() function is useful, but non essential for most
applications, and the underlying printf() call required cost an
additional 1K of RAM on first use, which is currently above the budget for
An e-compass solution requires knowwlede two pieces of data to provide an
- Accurate calibration of the magnetometer hardware so that reliable
measurements can be taken.
- Knowledge of the pitch and roll of of device, so that the correct
components of the X/Y and Z axis sensors of the magnetomer can be used
to sense the magnetic field in a horizontal plane regardless of the tilt
of the device.
This commit represent changes to the MicroBitAccelerometer and MicroBitCompass
classes to implemen tthese goals. More specifically, this commit provides:
- The introduciton of an interactive calibration 'game', that can rapidly
gather all the data required to calibrate the compass.
- An improved calibration algorithm based on a Least Mean Squares approach of
compass samples, as documened in Freescale Application Note AN4248.
- The inclusion of a simple Matrix4 class to enable efficient Least Mean
- A change from asynchronous to synchronous calibration of the compass when
first used. This is in repsonse to a feature request for this from users
and high level languages using microbit-dal.
- Support for detemrining tilt and roll angle in MicroBitAccelerometer
- Support for multiple co-ordinate spaces in MicroBitAccelerometer and
MicroBitCompass. Data can now be read in either RAW (unaltered) data.
MICORBIT_SIMPLE_CARTESIAN (as used previously) or NORTH_EAST_DOWN
(the industry convention in mobile phones, tablets and aviation)
- Implementation of a tilt compensated algorithm, used when determining
Freefall now detected when the net force on the device drops below 0.4g,
rather than 0.2g as previously defined. This improves sensitivity, without
generating false positives under common use.
Also correction of minor typos / layout errors.
- updated acceleration threshold event names to reflect numeric values e.g.
GESTURE_3G, GESTURE_6G, GESTURE_8G.
- Add scoping to elements of SimpleGesture enum.
- Code scrub of code layout caused by editor with incorrect configuration.
- rename of internal state variables and functions to better reflect use.
- added clarification to some comments.
- BLUEZONE mode renamed to PairingMode (by popular request).
- Added timeout of 90 seconds before automatic device reboot.
- Move from a scroll to a print based algorithm to improve the amount of time key is displayed fully.
- Added compulsory 'click to bond' button press.
- Improved response time of tick/cross being displayed.
The following postures of the device are now detected:
In addition, the following gestures are inferred:
- WHEEE (>=3g)
- SICK (>=5g)
- UNCONSCIOUS (>=8g)
Events are now triggered on the MessageBus upon the transition from one posture/gesture to another,
and a synchronous getGesture() method is now also provided to interogate the last gesture recognised.
I should be noted that the default accelerator range of +/-2g will be insufficient to detect some of
the events noted above, and MicroBitAccelerometer::setRange() should be used to increase the range