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
disabled.
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
other micro:bits.
Previously, to light sense a user would have to configure a
MicroBitLightSensor instance themselves, and flip the display mode
manually. This is difficult in languages that target our API.
This commit resolves that by adding a new method readLightLevel which
flips the display mode, and instantiates a light sensor.
When changing the mode, the tickSpeed is also modified to reduce
artefacts on the display.
Added a new class called MicroBitLightSensor which interleaves sensing
with the display.
This class takes advantage of the previous commits which add a dynamic
system tick, and a new display mode for the display.
A future optimisation would be for the display to handle the instantion
of a light sensor when the display mode is changed!
This commit adds a mutator that dynamically reconfigures the
systemTicker to call systemTick at a different period to the default.
The accessor returns the current tick speed in milliseconds.
The accessor is now also used in scheduler_tick to keep timing as
accurate as possible.
MICROBIT_DISPLAY_REFRESH_PERIOD has now been removed, and replaced with
MICROBIT_DEFAULT_TICK_PERIOD.
This commit introduces a new display mode,
DISPLAY_MODE_BLACK_AND_WHITE_LIGHT_SENSE, where the 4th render in
every “frame” is dropped allowing for other components that use the
display to use this dropped frame for processing. This is in
preparation for Light Sensing on the 5x5 LED matrix.
An accessor has also been added to MicroBitDisplay to check the current
display mode!
BLE maintains metadata on its characterisitics, some of which record whether
or not a central device (phone/tablet) wishes to receive notifications when a
given BLE characteristic changes value. One such characterisitic is used as
part of a core BLE service to indicate of the BLE profile of a device has
changed.
IOS is heavily reliant on this feature, and expects the state of this metadata
to be persistent across device reboots. This patch ensures that this metadata
is always set to allow Service Changed indications to be propagated to central
devices.
calibration
MicroBitCompass initiates a calibration procedure on demand if a heading is
requested from an uncalibrated device. The BLE MagnetometerService also
attempts to retrieve a heading periodically, but it is not good behaviour to
initiate calibration as a response to this.
This patch introduces a check such that the BLE MagnetometerService will only
attempt to read heading data from a previously calibrated compass.
BLE central devices (such as mobile phones/tablets) are permitted to cache the
list of services and characteristics provided by a BLE peripheral such as the
micro:bit. This was causing compatibility problems with IOS during FOTA
flashing, as the the list of BLE services may change after flashing.
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.
Added MicroBitConfig.h option to enable/disable whitelisting
Added MicroBitConfig.h option to enable/disable limited period advertising
Added support for limited period advertising
Minor code cleanups
See bbc/microbit-extras/issues/#1100 or lancaster-university/microbit-dal/issues/5 for full details.
Summary:
A stride of 0 would lock the calling fiber indefinitely, which was not the expected behaviour
for many people.
This update fixes this issue in both animate and scroll, returning immediately when there is
a stride of zero.
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.
Replaced newer struct-style initialisation of CompassSample in MicroBit.cpp
with the more traditional constructor-style initialisation, to enfore
C98 compliance.
Closes#74
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
channel.
Based on the previous commit, the api for MicroBitPin
has two new accessor methods:
* getAnalogPeriodUs
* getAnalogPeriod
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.
Dynamic pwm previously didn't round robin transient pwm channels,
and would therefore bias towards the first transient channel it found.
This update ensures that there is now an equal opportunity for all
channels to be considered for redirection.
Previously there would be the possibility of the period being reset
each time a new DynamicPwm was instantiated. This has now been
removed from the constructor, and the comments have been updated
All internal uses of accelerometer sample values now updated to access the
data via accessor methods. This now ensures consistent use irrespective of
the coordinate system used.
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
micro:bit.
An e-compass solution requires knowwlede two pieces of data to provide an
accurate heading:
- 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
Squares implementation.
- 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
device heading.
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.
Whilst Android devices permit explicit initiation of the BLE pairing process,
IOS based devices are only capable of implicit initiation of pairing based
on accessing a protected characteristic. Adding read capability to the
ControlPoint characteristic provides a safe and convenient way for IOS devices
to initiate pairing.
Minor amends:
- bleDisconnectionCallback signature change
- bleSetAdvertisingInterval now takes milliseconds as a parameter
- event based invocation of DFU bootloader
More specifically:
- 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.
Changes to default BLE name. During normal operation, all micro:bits now have the same name: BBC micro:bit
When pairing mode (AKA BLUEZONE) is entered, device name details re appended as before, to give BBC micro:bit [<name>]
This is to provide a degree of anonymity to users, to make tracking of kids more difficult.
This option is now configured when the BLE stack is initialised. This ensures that SoftDevice is never
starved of CPU during periods of criticality. This does lock out the CPU for application use, but prevents
MIC failures caused by __disable_irq() operations (as found in the mbed Ticker API for example).
Minor amends:
- bleDisconnectionCallback signature change
- bleSetAdvertisingInterval now takes milliseconds as a parameter
- event based invocation of DFU bootloader
The following postures of the device are now detected:
- TILT_UP
- TILT_DOWN
- TILT_LEFT
- TILT_RIGHT
- FACE_UP
- FACE_DOWN
In addition, the following gestures are inferred:
- NONE
- SHAKE
- FREEFALL
- 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
if required.
- LFSR generated values in a subset of the range requested (rounded to the nearest lower power of 2).
Corrected by increasing the number of bits usedby one, such that it now generated st least the power of 2 greater.
- replaced enable/disable of interrupts with a local snapshot of randomValue. Much of the nordic software is sensitive to interrupt timings,
so best avoided where possible. Chance of race condition is low, and effect is minimal (duplicate number returned).
- Removed flashcode base authorization
- silenced unused parameter in MicroBitHeapAllocator
- bugfixed BLUEZONE mode so that sensor data is still available via BLE
The serial baud rate is set duing construction of the uBit object. We
don't need to do it again, and especially with fixed values that can't
be overridden.
Uisng libc's implementation is likely to be safer than rolling our own. At least
the failure modes are well documented. (glibc's implementation of rand() is
actually not bad).
The LFSR used only provides 1 bit of random data each time it is cycled.
This implementation generates the minimum number of bits needed. Further
it discards numbers that are bigger than required and re-calculates -
this keeps the distribution flat.
If BLE is connected when performing a hard reset, attempt to disconnect
first to allow the remote peer to handle the disconnect gracefully
without haing to wait for a supervision timeout.
- refactored BLE funcitonality into BLEManager class.
- added security requirements standard BLE profile services.
- updated bluezone pairing process to use BLE passkey exchange.
Also recalibrated loop timers in MicroBitDisplay::Error(), as used by panic()...
strange these now seem off by several orders of magnitude.
TODO: Ensure CPU is running at correct internal frequency with an oscilloscope test...
Whilst a little more invasive change than the previous warnings
supression this is more correct and more obvious as to what's being done,
and what warnigns will remain in place for the rest of the comilation
unit.
Unfortunately we can't turn it off just while nrf_soc.h is being included
as the way the defines are used the compiler can't tell the parameters
are unused until the end of the compilation unit. So we can't use the
more normal
as that pops the supression too early.
WARNING: including nrf_soc.h will turn off unused-function warnings for
the rest of the compilation unit - see included nrf_svc.h
- Enures an event listener is not deleted whilst a fiber is activiely processing a queue
- Added support for resurrection of event listeners in cases where identical listeners are removed/added repetitively.
- Add maximum depth for event queues, to prevent buggy scripts causing total memory exhaustion.
- Suppress generation of A/B click events when A+B click is generated
- preservation of event ordering on messagebus for resursive event generation cases.
- bugfix of message bus processing to prevent occasional dual processing of events
- bugfix MicroBitDisplay to behave correctly when delay parameter is zero.