Implementation: MQTT Publisher/Subscriber on MXChip IoT DevKit

[Hugofslopes]

1 - Short description

Implement and verify MQTT publisher and subscriber functionality on the MXChip IoT DevKit. This issue focuses on utilizing the device's integrated Wi-Fi and existing SDKs to interact with the Mosquitto broker, establishing a baseline for device-to-cloud telemetry.

2 - Tasks

• Set up the development environment for MXChip (Azure IoT / Arduino IDE).
• Develop a firmware module to act as an MQTT Publisher (sending sensor data).
• Develop a firmware module to act as an MQTT Subscriber (listening for command topics).
• Validate message round-trip between the DevKit and the Mosquitto broker.

3 - Acceptance Criteria

• A Markdown document detailing the implementation steps is provided.
• Verified source code for both Publisher and Subscriber roles is committed.
• Documentation includes setup instructions for the MXChip Wi-Fi connection.

4 - Notes / Implementation details

• Use the PubSubClient library for MQTT support.
• Ensure the code includes logic to handle reconnects if the Wi-Fi or MQTT connection drops.
• Code Reference: Provide snippets for mqtt_connect(), publish_data(), and callback() (for subscription).