modules: cloud: integrate nRF Cloud CoAP connectivity module

[nmpluta]

MR Description

This MR integrates the cloud module from Asset Tracker Template v1.1.1 into the fire detection system, providing seamless nRF Cloud connectivity for sensor data transmission.

🎯 Overview

The integration adapts Nordic's proven cloud connectivity architecture to work with our fire detection system, enabling real-time sensor data transmission to nRF Cloud via CoAP protocol.

📋 Features Implemented

Cloud Module Integration (modules: cloud: integrate nRF Cloud CoAP connectivity module)

• ✅ State Machine Architecture: Robust connection management with disconnected/connecting/connected states
• ✅ ZBUS Integration: Seamless communication with sensor and network modules
• ✅ Automatic Data Transmission: All fire detection sensors (BME280, CCS811, HM3301, SEN0466) data sent to cloud
• ✅ Connection Resilience: Configurable backoff strategies (exponential/linear/none) for reconnection
• ✅ Device Shadow Support: Configuration management via nRF Cloud device shadow
• ✅ Shell Commands: Interactive cloud commands for testing and debugging
• ✅ Comprehensive Error Handling: Watchdog integration and fatal error management
• ✅ Credentials Management: Automatic nRF Cloud credentials validation

Timestamp Enhancement (modules: sensor: add configurable UTC timestamps to sensor data)

• ✅ Configurable Timestamps: CONFIG_SENSOR_MODULE_TIMESTAMP enables UTC epoch timestamps
• ✅ Smart Fallback: Uses date_time_now() when available, k_uptime_get() otherwise
• ✅ Cloud Compatibility: Proper timestamp handling for nRF Cloud data correlation
• ✅ Enhanced Logging: Human-readable timestamp display in controller module

🔧 Key Adaptations from Original Asset Tracker Template

Architecture Integration

- Original: GPS, accelerometer, battery sensors
+ Fire Detection: BME280, CCS811, HM3301, SEN0466 sensors
- Original: Location-based tracking
+ Fire Detection: Environmental monitoring (temp, CO2, CO, PM, etc.)

ZBUS Channel Mapping

Original Channel	Fire Detection Equivalent	Purpose
SENSOR_CHAN	sensor_chan	Environmental sensor data
NETWORK_CHAN	network_chan	Connectivity status
LOCATION_CHAN	(removed)	Not applicable for fire detection

Sensor Data Transmission

// Original Asset Tracker
nrf_cloud_coap_sensor_send("GPS", lat_lng, timestamp, confirmable);

// Fire Detection System
nrf_cloud_coap_sensor_send("TEMP", temperature, timestamp, confirmable);
nrf_cloud_coap_sensor_send("CO2", co2_level, timestamp, confirmable);
nrf_cloud_coap_sensor_send("CO", co_level, timestamp, confirmable);
nrf_cloud_coap_sensor_send("PM2_5", pm2_5_level, timestamp, confirmable);

Smart Timestamp Handling

• With CONFIG_SENSOR_MODULE_TIMESTAMP=y: Real UTC timestamps for accurate cloud correlation
• With CONFIG_SENSOR_MODULE_TIMESTAMP=n: Uses NRF_CLOUD_NO_TIMESTAMP to let nRF Cloud assign server time

🏗️ System Architecture

Fire Detection Application
    ↓
┌─────────────────────────────────────────────────────────────┐
│                    ZBUS Message Bus                         │
├─────────────────────────────────────────────────────────────┤
│ Sensor Module → Cloud Module → nRF Cloud CoAP              │
│ Network Module ↗              ↘ Device Shadow              │
│ Controller Module              ↘ Sensor Data Streaming     │
└─────────────────────────────────────────────────────────────┘
    ↓
nRF Cloud Platform

📊 Configuration Options

Cloud Module Settings

Config	Default	Description
CLOUD_MODULE_CONFIRMABLE_MESSAGES	n	Use CoAP confirmable messages
CLOUD_MODULE_BACKOFF_INITIAL_SECONDS	60	Initial reconnection delay
CLOUD_MODULE_BACKOFF_TYPE	LINEAR	Backoff strategy
CLOUD_MODULE_THREAD_STACK_SIZE	6144	Cloud thread stack size

nRF Cloud Integration

CONFIG_NRF_CLOUD=y
CONFIG_NRF_CLOUD_COAP=y
CONFIG_NRF_CLOUD_CLIENT_ID_SRC_IMEI=y
CONFIG_NRF_CLOUD_CHECK_CREDENTIALS=y

🔍 Transmission Data Points

The system automatically transmits all fire detection sensor readings:

• Environmental: Temperature, humidity, air pressure
• Air Quality: CO2, VOC levels
• Particulate Matter: PM1.0, PM2.5, PM10
• Hazardous Gas: CO concentration
• Network Quality: RSRP, connection evaluation

The integration provides a robust foundation for cloud-connected fire detection systems.

Original Source: Asset Tracker Template - Cloud Module

Closes #21

Signed-off-by: Natalia Pluta pluta.natalia.m@gmail.com

[Copilot]

Pull Request Overview

This PR integrates nRF Cloud CoAP connectivity by adapting Nordic's cloud module from the Asset Tracker Template. The system now transmits sensor data (temperature, humidity, air pressure, CO2, VOC, particulate matter, and CO levels) to nRF Cloud using CoAP protocol with configurable timestamps.

• Adds a complete cloud connectivity module with state machine architecture and automatic reconnection handling
• Implements configurable UTC timestamps for sensor data with fallback mechanism
• Refactors error handling to use a common app_common.h header instead of app_fatal_error.h

Reviewed Changes

Copilot reviewed 16 out of 16 changed files in this pull request and generated 1 comment.

Show a summary per file

File	Description
app/src/modules/sensor/sensor_module.h	Adds conditional timestamp field to sensor messages
app/src/modules/sensor/sensor_module.c	Implements UTC timestamp generation with fallback logic
app/src/modules/sensor/Kconfig.sensor	Adds timestamp configuration option
app/src/modules/network/network_shell.c	Minor shell output enhancement for RSRP display
app/src/modules/network/network_module.c	Updates include to use common error handling
app/src/modules/controller/controller_module.c	Conditionally logs timestamps based on configuration
app/src/modules/cloud/	Complete cloud module implementation with CoAP connectivity
app/src/app_fatal_error.h	Removed in favor of common error handling
app/src/app_common.h	New common header with error handling and utility macros
app/prj.conf	Adds nRF Cloud and CoAP configuration
app/Kconfig	Includes cloud module configuration
app/CMakeLists.txt	Adds cloud module to build

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