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.
Application should be able to add some optional callbacks if it needs to.
Ofcourse there is a penalty of 8-12 bytes per callback, but there can be
certain needs of the application that needs to be met for example setting
up a link check request etc.
We have introduced a structure that contains callbacks for the application use.
- 'events' callback is mandatory, user must assign it. Because this callback brings
state changes for the application. We cannot segregate this into individual handlers
because of RAM penalty.
- Other calbacks (none of them are implemented yet are optional).
Example of using the API is provided with doxygen
All Mbed-OS drivers for LoRa radio devices must implement
this pure virtual class in order to be compliant with Mbed-OS
applications.
This class comes loaded with all necessary data structures.
The implementations of this class can come out of tree.
Hasnain Virk