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diff --git a/pw_rpc/py/pw_rpc/console_tools/watchdog.py b/pw_rpc/py/pw_rpc/console_tools/watchdog.py
new file mode 100644
index 000000000..bcc9ffe8f
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+++ b/pw_rpc/py/pw_rpc/console_tools/watchdog.py
@@ -0,0 +1,83 @@
+# Copyright 2021 The Pigweed Authors
+#
+# Licensed under the Apache License, Version 2.0 (the "License"); you may not
+# use this file except in compliance with the License. You may obtain a copy of
+# the License at
+#
+#     https://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
+# WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
+# License for the specific language governing permissions and limitations under
+# the License.
+"""Simple watchdog class."""
+
+import threading
+from typing import Any, Callable
+
+
+class Watchdog:
+    """Simple class that times out unless reset.
+
+    This class could be used, for example, to track a device's connection state
+    for devices that send a periodic heartbeat packet.
+    """
+    def __init__(self,
+                 on_reset: Callable[[], Any],
+                 on_expiration: Callable[[], Any],
+                 while_expired: Callable[[], Any] = lambda: None,
+                 timeout_s: float = 1,
+                 expired_timeout_s: float = None):
+        """Creates a watchdog; start() must be called to start it.
+
+        Args:
+          on_reset: Function called when the watchdog is reset after having
+              expired.
+          on_expiration: Function called when the timeout expires.
+          while_expired: Function called repeatedly while the watchdog is
+              expired.
+          timeout_s: If reset() is not called for timeout_s, the watchdog
+              expires and calls the on_expiration callback.
+          expired_timeout_s: While expired, the watchdog calls the
+              while_expired callback every expired_timeout_s.
+        """
+        self._on_reset = on_reset
+        self._on_expiration = on_expiration
+        self._while_expired = while_expired
+
+        self.timeout_s = timeout_s
+
+        if expired_timeout_s is None:
+            self.expired_timeout_s = self.timeout_s * 10
+        else:
+            self.expired_timeout_s = expired_timeout_s
+
+        self.expired: bool = False
+        self._watchdog = threading.Timer(0, self._timeout_expired)
+
+    def start(self) -> None:
+        """Starts the watchdog; must be called for the watchdog to work."""
+        self._watchdog.cancel()
+        self._watchdog = threading.Timer(
+            self.expired_timeout_s if self.expired else self.timeout_s,
+            self._timeout_expired)
+        self._watchdog.daemon = True
+        self._watchdog.start()
+
+    def reset(self) -> None:
+        """Resets the timeout; calls the on_reset callback if expired."""
+        if self.expired:
+            self.expired = False
+            self._on_reset()
+
+        self.start()
+
+    def _timeout_expired(self) -> None:
+        if self.expired:
+            self._while_expired()
+        else:
+            self.expired = True
+            self._on_expiration()
+
+        self.start()