initial

.gitignore

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+ENV
+*.pyc
+src/.venv/*
+

docs/notes.txt

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+Sending messages downlink via MQTT: https://www.thethingsindustries.com/docs/integrations/mqtt/#publishing-downlink-traffic
+
+Topics for messages at TTN: https://www.thethingsindustries.com/docs/integrations/mqtt/#publishing-downlink-traffic
+

src/preprocess.py

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+from loguru import logger
+import paho.mqtt.client as mqtt
+import os
+import sys
+import ssl
+import json
+import base64
+import struct
+
+def mqttOnConnectCallback(client, userdata, flags, rc):
+    logger.info("mqtt connected")
+    client.subscribe(config['MQTT_IN_TOPIC'])
+    logger.info(f"subscribed to {config['MQTT_IN_TOPIC']}")
+
+def mqttOnMessageCallback(client, userdata, message):
+    try:
+        topic = message.topic
+        payload = message.payload
+        logger.debug(f"mqtt message received: {topic} -> {payload}")
+        parse_payload = json.loads(payload)
+        frame = base64.b64decode(parse_payload['uplink_message']['frm_payload'])
+        logger.info(f"{frame=}")
+        status = struct.unpack('<H', frame[0:2])[0]
+        logger.info(f"{status=}")
+
+        if (status == 4):
+            logger.info("Start up message received")
+            # send downlink message with labels
+            sensor_addrs = []
+            for i in range(0, 4):
+                start_index = 2 + (i * 8)
+                end_index = start_index + 8
+                sensor_addrs.append(struct.unpack('<Q', frame[start_index:end_index])[0])
+                logger.debug(f"sensor {i}: 0x{sensor_addrs[i]:016x}")
+
+        else:
+            logger.info("Regular message received")
+            # continue to parse and process message
+            sensor_addrs = []
+            sensor_values = []
+            for i in range(0, 4):
+                addr_start_index = 2 + (i * (8 + 4))
+                addr_end_index = addr_start_index + 8
+                sensor_addrs.append(struct.unpack('<Q', frame[addr_start_index:addr_end_index])[0])
+                value_start_index = addr_end_index
+                value_end_index = value_start_index + 4
+                sensor_values.append(struct.unpack('<i', frame[value_start_index:value_end_index])[0] / 128)
+                logger.debug(f"sensor {i}: 0x{sensor_addrs[i]:016x} = {sensor_values[i]:.2f} °C")
+
+    except Exception as e:
+        logger.error(f"unable to parse message {payload}, {e}")
+
+def mqttOnDisconnectCallback(client, userdata, rc):
+    pass
+
+logger.info("preprocess starting")
+
+
+
+REQUIRED_CONFIG_OPTIONS = [ 
+    'MQTT_LOGIN',
+    'MQTT_PASSWORD',
+    'MQTT_BROKER',
+    'MQTT_PORT',
+    'MQTT_CA',
+    'MQTT_IN_TOPIC'
+]
+
+config = {}
+for rco in REQUIRED_CONFIG_OPTIONS:
+    try:
+        config[rco] = os.environ[rco]
+    except KeyError:
+        logger.error(f"{rco} is a required config option, not available in environment")
+        sys.exit(-1)
+
+
+
+client = mqtt.Client()
+client.on_message = mqttOnMessageCallback
+client.on_connect = mqttOnConnectCallback
+client.on_disconnect = mqttOnDisconnectCallback
+client.username_pw_set(config['MQTT_LOGIN'], config['MQTT_PASSWORD'])
+client.tls_set(
+    cert_reqs=ssl.CERT_REQUIRED,
+    ciphers=None
+)
+client.connect(config["MQTT_BROKER"], int(config["MQTT_PORT"]))
+logger.info("mqtt loop starting")
+client.loop_forever()
+
+
+
+

src/requirements.txt

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+loguru==0.6.0
+paho-mqtt==1.6.1