This commit also introduces API change for disconnect(). disconnect() will
now return LORAWAN_STATUS_DEVICE_OFF for successfull disconnect.
* LoRaWANStack::handle_tx() can be called with NULL buffer when length is 0.
This commit fixes the case where user has provided NULL buffer and length
is > max_possible_size.
handle_tx() now always returns LORAWAN_STATUS_PARAMETER_INVALID if given
buffer is NULL pointer and length > 0.
General error checking is added and some asserts are added for events.
Instead of initiating own timer objects we can use EventQueue::call_in() method
as we already have handle to EventQueue object.
Also setting timeout and starting timer has been combined to TimerStart method.
Baseline is changed to use a single set of data structures that simplifies the
code in the LoRaWANStack and Mac layer. We are now following certian rules for naming
data structures.
- All structures visible outside their domain are prefixed as 'lorawan_'
- All mac structures are prefixed as 'loramac_'
- All subsystem or module strucutures carry their name in prefix, like 'mcps_'
PHY layer still have legacy camel case data structures which will be entertained
later while we will be simplifying PHY layer.
Test cases are also updated with the new data structure naming conventions.
One major difference from the previous baseline is the removal of static buffer
from mcps indication. And we do not copy data from stack buffer to rx_msg buffer.
This saves at least 512 bytes.
It may look like now that if we have received something but the user have not read
from the buffer, then the buffer will be overwritten and we will lose previous frame.
Yes, we will. But the same will happen even if we would have copied the buffer into rx_msg
because then the rx_msg gets overwritten. So we decide to abandon copying the buffer at
multiple locations. We inform the user about reception, if the user doesn't read and
the data gets overwritten, then so be it.
Ticker objects embeded in TimerEvent_t data structure were getting constructed
even for the non LORAWAN builds. And that's what was bloating the builds.
We now lazy initialize them using Mbed-OS utility clas SingletonPtr.
A central data structure has been created that carries all the protocol level
variables for the Mac layer. This is important as we are going to break down
MAC services into subsystems and we will pass around common data using that data structure.
Time handler class had a c style callback attached to it which
had been hampering us to be fully object oriented.
That particular callback is changed to Mbed Callback which is attatched
to a specific object hence allowing us to be fully object oriented.
LoRaWANTimer is now called as LoRaWANTimeHandler class as this class handles both
current time and timer functionalities.
Some refactoring on how LoRa objects are created was needed:
- LoRaWANTimeHandler object is created by LoRaWANStack and shares with LoRaMac and PHY.
- LoRaPHY object is now member of LoRaWANStack class instead of static variable in source file.
MAC layer is now a class rather than being a blob.
In addition to that Mac commands are now being handled in
a seperate subsystem (a class of its own). In future we
will do the same with othe sublayers of MAC like MLME, MCPS etc.
The drive behind this exercise is to make MAC and supporting layers
into an object oriented system.
Major bug fixes include:
- last join time inclusion in band parameters
- disabling rx2 window if we missed the slot already
- MLME uplink schdule hook
- nbRep according to spec
- maintaining datarate after successful joining
- suppressing MLME requests if MAC is in TX_DELAYED state
- Uplink dwell time verification
Some missing features are implemented. Details are as follows.
Support for LinkCheckRequet:
An application API is added, add_link_check_request() to delegate a
request for Link Check Request MAC command.
* Application provides a callback function that needs to be called on reception of
link check response.
* Mac command is piggybacked with data frames.
This API makes the sticky MAC command stick with the application payloads until/unless
the application un-sticks the said mac command using remove_link_check_request() API.
Handling fPending bit:
If in the Downlink, we get the fPending bit set in fctrl octet,
we attempt to send an empty message back to Network Server to
open additional Receive windows. This operation is independent
of the application. An RX_DONE event is queued bedore generating
the said empty message. Specification does not mention what can be the
type of that empty message. We have decided it to be of CONFIRMED
type as it gives us an added benefit of retries if the corresponding
RX slots are missed.
Radio event callbacks as Mbed callbacks:
radio_events_t structure has been carrying C-style callbacks which was
inherited from the legacy code. These callbacks has now been changed to
Mbed Callbacks that makes sure that we can be object oriented from now
on.
We had a lot of static objects which would get constructed and hence
pull in some of the LoRaWAN code into the builds for other technologies.
Such objects have been now lazily initialized using utility class
SingletonPtr.
Current implementation uses high resolution timers to calculate elapsed time.
This prevents for example deep sleep completely and causes unnecessary timer
events.
This commit changes implamentation to use EventQueue::tick() to get elapsed time.
All network interfaces for LoRaWAN protocol must implement this
class. In order to be compatible with Mbed-OS applications, any
implementation of this class must use the data structures and
Mbed-OS timers provided.
lorawan_data_structures may look repetitive but this is essential
as we have a plan to use a reference implementation for LoRaWAN mac
layer from Semtech. Some of the data structures provide seemless
transition from semtech implementation (as MAC layer) to the Mbed-OS
control layers above.
features/lorawan/lorastack is the placeholder for future items like mac and
phy layers. system/ will contain all the common bits.
Antti Kauppila
Hasnain Virk
Kimmo Vaisanen