add example script

Signed-off-by: YoungSoo Shin <shinys000114@gmail.com>

example/logger/README.md

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+# Power Consumption Logger Example
+
+Based on this script, you can monitor power consumption and implement graph plotting.
+
+## How to Run the Script
+
+### Install Python Virtual Environment
+
+```shell
+sudo apt install virtualenv
+virtualenv venv
+. venv/bin/activate
+```
+
+### Install require package
+
+```shell
+pip install grpcio-tools requests websockets protobuf
+```
+
+### `status_pb2.py` 빌드
+
+```shell
+python -m grpc_tools.protoc -I ../../proto --python_out=. status.proto
+```
+
+### Execute script
+
+```shell
+# python3 logger.py -u <username> -p <password> <address>
+python3 logger.py -u admin -p password 192.168.30.5
+```

example/logger/logger.py

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+import argparse
+import asyncio
+import requests
+# Import the status_pb2.py file generated by `protoc`.
+# This file must be in the same directory as logger.py.
+import status_pb2
+import websockets
+from datetime import datetime
+
+
+class OdroidPowerLogger:
+    """
+    A class to connect to the Odroid Smart Power monitoring server and log power data.
+    1. Logs into the server via an HTTP POST request to obtain an authentication token.
+    2. Connects to the WebSocket using the obtained token.
+    3. Receives and decodes binary data in Protobuf format, then prints it.
+    """
+
+    def __init__(self, host, username, password):
+        self.host = host
+        self.username = username
+        self.password = password
+        self.base_url = f"http://{self.host}"
+        self.ws_url = f"ws://{self.host}/ws"
+        self.token = None
+
+    def login(self):
+        """Logs into the server to retrieve an authentication token."""
+        login_url = f"{self.base_url}/login"
+        payload = {"username": self.username, "password": self.password}
+        try:
+            print(f"Attempting to log in to '{login_url}'...")
+            response = requests.post(login_url, json=payload, timeout=5)
+            response.raise_for_status()
+
+            response_json = response.json()
+            if "token" in response_json:
+                self.token = response_json["token"]
+                print("Login successful! Token received.")
+                return True
+            else:
+                print("Login failed: No token in response.")
+                return False
+        except requests.exceptions.RequestException as e:
+            print(f"Error during login: {e}")
+            return False
+
+    async def listen_power_data(self):
+        """Connects to the WebSocket to receive and log power data."""
+        if not self.token:
+            print("Cannot connect to WebSocket without an authentication token.")
+            return
+
+        # Add the authentication token as a query parameter
+        uri = f"{self.ws_url}?token={self.token}"
+
+        try:
+            async with websockets.connect(uri) as websocket:
+                print(f"Connected to WebSocket: {uri}")
+                while True:
+                    # Receive binary message from the server
+                    message_bytes = await websocket.recv()
+
+                    # Decode the Protobuf message
+                    status_message = status_pb2.StatusMessage()
+                    status_message.ParseFromString(message_bytes)
+
+                    # Process only if the payload type is 'sensor_data'
+                    if status_message.WhichOneof('payload') == 'sensor_data':
+                        sensor_data = status_message.sensor_data
+                        ts = datetime.fromtimestamp(sensor_data.timestamp).strftime('%Y-%m-%d %H:%M:%S')
+
+                        print(f"--- {ts} (Uptime: {sensor_data.uptime_sec}s) ---")
+
+                        # Print data for each channel
+                        for name, channel in [('VIN', sensor_data.vin), ('MAIN', sensor_data.main),
+                                              ('USB', sensor_data.usb)]:
+                            print(
+                                f"  {name:<4}: {channel.voltage:5.2f} V | {channel.current:5.3f} A | {channel.power:5.2f} W")
+
+        except websockets.exceptions.ConnectionClosed as e:
+            print(f"WebSocket connection closed: {e}")
+        except Exception as e:
+            print(f"Error during WebSocket processing: {e}")
+
+    async def run(self):
+        """Runs the logger."""
+        if self.login():
+            await self.listen_power_data()
+
+
+async def main():
+    parser = argparse.ArgumentParser(description="Odroid Smart Power Data Logger")
+    parser.add_argument("host", help="Server's host address or IP (e.g., 192.168.1.10)")
+    parser.add_argument("-u", "--username", required=True, help="Login username")
+    parser.add_argument("-p", "--password", required=True, help="Login password")
+    args = parser.parse_args()
+
+    logger = OdroidPowerLogger(host=args.host, username=args.username, password=args.password)
+    await logger.run()
+
+
+if __name__ == "__main__":
+    try:
+        asyncio.run(main())
+    except KeyboardInterrupt:
+        print("\nExiting program.")