update check_connection()

per nRF24/RF24Mesh#250

circuitpython_nrf24l01/rf24_mesh.py

@@ -40,6 +40,7 @@
     NETWORK_DEFAULT_ADDR,
     NETWORK_MULTICAST_ADDR,
     NETWORK_POLL,
+    NETWORK_PING,
     MESH_ADDR_RELEASE,
     MESH_ADDR_LOOKUP,
     MESH_ID_LOOKUP,
@@ -162,14 +163,23 @@ def _lookup_2_master(self, number: int, lookup_type: int) -> int:
             return struct.unpack("<H", self.frame_buf.message[:2])[0]
         return self.frame_buf.message[0]
 
-    def check_connection(self, attempts: int = 3) -> bool:
+    def check_connection(self, attempts: int = 3, ping_master: bool = False) -> bool:
         """Check for network connectivity (not for use on master node)."""
+        if not self._parent:
+            return True
+        if self.node_address == NETWORK_DEFAULT_ADDR:
+            return False
         for _ in range(attempts):
-            result = self.lookup_address(self._id)
-            if result in (-2, 0):
-                return False
-            if result == self.node_address:
-                return True
+            if ping_master:
+                result = self.lookup_address(self._id)
+                if result == -2:
+                    return False
+                if result == self.node_address:
+                    return True
+            else:  # ping parent
+                result = self.write(self._parent, NETWORK_PING, b"")
+                if result:
+                    return True
         return False
 
     def update(self) -> int:

docs/network_docs/mesh_api.rst

@@ -175,6 +175,31 @@ Advanced API
 
 .. automethod:: circuitpython_nrf24l01.rf24_mesh.RF24Mesh.check_connection
 
+    :param attempts: The number of attempts to test for active connection to the mesh network.
+    :param ping_master: If this parameter is set to `True`, then this function will verify the
+        connectivity by using `lookup_address()` to transact with the master node. Setting this
+        parameter to `False` will simply ping the node's parent.
+
+        .. warning::
+            Setting this parameter to `True` can result in performance cost when used in
+            a large mesh network. The disadvantages in such a situation are:
+
+            - increased load on master node
+            - increased network congestion
+            - unreliable connectivity information when a parent or grandparent of the current
+              node briefly loses connection.
+
+    :returns:
+        - `True` if connected to the mesh network (or current node is the master node).
+        - `False` if not connected to the mesh network or mesh network is unresponsive.
+
+    .. versionchanged:: 2.2.0
+        Added ``attempts`` and ``ping_master`` parameters; changed return value for master nodes
+
+        Previously, this function would return `False` when called from a master node.
+        This was changed to return `True` to help avoid erroneous user code calling
+        `renew_address()` on a master node.
+
 .. automethod:: circuitpython_nrf24l01.rf24_mesh.RF24Mesh.release_address
 
 .. autoproperty:: circuitpython_nrf24l01.rf24_mesh.RF24Mesh.allow_children