OpenThread network-wide time synchronization service is an experimental feature, not part of the standard Thread protocol.
Feature Overview:
* All the nodes in the same Thread partition sync to the same Thread network-wide time;
* Microsecond level time synchronization precision;
* Flexible time accuracy and time sync period configuration;
* APIs for application layer use case, support both CLI and NCP version.
The feature is wrapped by OPENTHREAD_CONFIG_ENABLE_TIME_SYNC, there's no change to current Thread 1.1
implementation if OPENTHREAD_CONFIG_ENABLE_TIME_SYNC is not enabled.
If OPENTHREAD_CONFIG_ENABLE_TIME_SYNC is enabled, the node could:
* Attach to a time sync enabled network, otherwise
* Attach to a standard Thread 1.1 network, otherwise
* Form a new time sync enabled network
In addition, if OPENTHREAD_CONFIG_TIME_SYNC_REQUIRED is also enable, the node could only:
* Attach to a time sync enabled network, otherwise
* Form a new time sync enabled network
Note:
Currently, the feature is only supported on nRF52840 and posix platforms. And the network time
is only synced among Routers and REEDs, the SEDs will be supported later as an optional feature.
This commit adds a new template class `ot::String<size>` which
implements a fixed-length character string. This class is then used as
return value of `ToString()` methods from different classes. This
simplifies the `ToString()` implementation and its use. This commit
also adds a unit test for `String`.
This commit adds a new feature/class namely `AnnounceSender` which
enables periodic transmission of MLE Announce messages on all
channels. The feature can be enabled using the config option
`OPENTHREAD_CONFIG_ENABLE_ANNOUNCE_SENDER` (disabled by default).
This commit also adds some new helper methods in `Mac::ChannelMask`
to get number of channels in a given mask, and operator overloads
to compare two masks.
This commit adds a `Mac::ChannelMask` class to define a channel (a
`uint32_t` bit-vector specifying a set of channels). The `ChannelMask`
class provides methods to add/remove channel to the mask, intersect
two masks, and iterate through the channels in the mask. A unit test
for the new class is also added.
This commit new configuration option `enable-multiple-instances` and
its corresponding option `OPENTHREAD_ENABLE_MULTIPLE_INSTANCES`. When
enabled OpenThread supports handling of multiple instances. By default
this is disabled.
This commit also adds two optimizations for single instance case to
simplify the code and also help reduce memory/RAM usage:
(1) OpenThread objects/classes typically keep a reference to a higher
level object (e.g., many classes keep track of owning `ThreadNetif`)
to be able to access other objects/methods within OpenThread class
hierarchy. In single instance mode, the reference member variables are
removed and instead global functions are used to access the singleton
objects from one class to the other. To implement this, a group of
`<Object>Locator` classes are defined (e.g., `ThreadNetifLocator`,
etc.) which are then used as base class of other OpenThread classes.
(2) OpenThread objects which provide a callback/handler (e.g.,
`Timer`, `Tasklet`, etc.) have `void *mContext` member variable which
is used to keep track of the owner of the object. In single instance
mode the `mConext` member variables are removed since the owner is
expected to be a singleton and can be uniquely determined from the
callback function.
To implement this, two changes are made: First the handler methods are
modified to provide a reference to the object (e.g., `Timer` handler
will provide a `Timer &aTimer` as a parameter of its handler
callback). Second, a new base class `Context` is introduced which
hides the implementation providing an arbitrary context information. A
new static method `GetOwner(aContext)` is added to classes which own a
callback providing objects. This method help convert a `Context` to
the reference of the owner class object.
Some radio chips have memory-mapped regions for transmit and receive buffers.
This change allows the radio driver to pass those buffers, when available,
directly to upper layers and avoid unnecessary copies.
Zhanglong Xia