Google Cloud IotCore with Raspberry PI

In my previous blog post, I have written about the integration of Google Cloud IoTCore using UDOO and how the temperature information is sent up to Pub/Sub. In the post, I will describe the integration of Raspberry PI to Google Cloud IoTCore. The primary communication protocol between the sensors and the IoTHub is mosquitto MQTT.

For this setup, I have a temperature sensor using ESP8266 flashed with ESP Easy firmware. The ESP and sensor are battery power which set to wake up every 60 minutes to take the measurement and transfer this to Raspberry Pi. The IOT bridge is written in Python which bridges the internal MQTT messages and Google Cloud IoTCore.

The sensor is battery power using a 3rd party Nokia BL-5C (1020 mah) rechargeable battery. This can be cheaply purchased from many battery shops or online. I have used 2 versions of the Wemos Mini charging shield version (1.1and 1.2). The details on how to modify the version 1.1 to be able to read the voltage level of the battery can be found at this blog post.

The diagram above shows the entire process flow. The telemetry data from the sensors are stored in the BigQuery database and the Device State information is stored in Cloud Firestore.

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