DIY Home Lab Sensors: Build, Integrate, and Monitor with ESP32 & Raspberry Pi

Project 3 — PIR Security Alarm with Raspberry Pi

Parts list

• Raspberry Pi with Raspbian or similar OS
• Passive infrared (PIR) motion sensor
• Optional buzzer, relay for alarm siren, and battery-backed power supply

Alarm logic and Home Assistant link

Connect the PIR output to a GPIO pin on the Raspberry Pi with a simple pull-down resistor. Implement a small process or use Home Assistant’s GPIO integration to react to motion events. Use local notifications or Home Assistant automations to notify on motion and optionally pair with camera snapshots while keeping privacy in mind.

Placement tips

Mount PIR sensors on an interior wall or ceiling about 2–2.5 meters off the floor for optimal coverage. Avoid pointing at heat sources, vents, or windows to reduce false triggers.

Expected cost and build time

• Estimated cost: $20–60 depending on Pi model and accessories
• Build time: 30–60 minutes

Security considerations

• Keep the Pi and network services updated and avoid exposing management ports to the internet
• Use local automations and encrypted MQTT to reduce attack surface

Data ingestion and logging

High-level pipeline choices

• MQTT → Home Assistant: Lightweight and widely supported; devices publish to MQTT topics and Home Assistant creates sensor entities
• MQTT → Graylog: For lab-grade logging and analytics, send sensor messages to a Graylog input for parsing, dashboards, and retention controls
• Direct HTTP → Local database: Push sensor data directly to a local time-series database for complex analytics

Design tips for reliable logging

• Use retained messages or QoS 1 for critical MQTT measurements to reduce data loss
• Tag messages with node IDs, sensor types, and timestamps to simplify parsing in Graylog
• Store raw data locally and use periodic backups to avoid surprises when cloud services fail

Storage and visualization

Use Home Assistant for dashboards, automations, and quick history views. Use Graylog or a time-series DB for long-term retention, aggregation, and forensic analysis. Keep retention policies reasonable to manage storage costs and performance.

Deployment tips (placement, power, enclosure, reliability)

• Place sensors away from doors and windows for stable readings; for freezer monitoring, put sensors near items you care about rather than on the door
• Power: choose wired power for critical nodes and battery for flexible placement
• Enclosures: use vented holes for air sensors and gasketed enclosures for damp environments
• Reliability: schedule watchdog restarts, monitor uptime with pings or heartbeat messages, and store a small health log locally

Troubleshooting & FAQs

• My readings are noisy: try averaging or filtering measurements and check wiring length for I2C; replace cheap sensor modules if noise persists
• Wireless range is poor: add a Wi‑Fi extender, use MQTT over Ethernet for gateway devices, or switch to LoRa for long-range needs
• CO2 drifts slowly: follow manufacturer calibration guidance and log baselines in well-ventilated environments to detect drift
• How often to calibrate: for most indoor sensors, a few times a year or when readings deviate from expected values

Privacy & alternative sensing

If privacy is a concern, avoid cameras and opt for anonymous thermal or heat-based sensing for occupancy. These sensors detect presence and movement patterns without capturing images, making them suitable for privacy-conscious environments.

Benefits of anonymous thermal sensing

• Preserves privacy while enabling occupancy-based automation
• Lower data sensitivity reduces compliance burdens in shared spaces
• Good fit for offices, meeting rooms, and rental properties where cameras are undesirable

Resources, community, and next steps

• Explore community forums and Reddit homelab threads for real-world examples and troubleshooting
• Try a small starter kit: one temp/humidity node and one CO2 node to learn the pipeline from sensor → MQTT → Home Assistant
• For privacy-first occupancy analytics, consider anonymous thermal sensing solutions from specialized vendors

Next steps

• Build one temp/humidity node and connect it to your local MQTT broker
• Add a CO2 sensor in a frequently used room and log trends for two weeks to set thresholds
• Deploy a Raspberry Pi with a PIR sensor for a basic alarm and integrate it into Home Assistant automations

Want a printable parts list or wiring diagram for each project? Create a simple checklist from the parts lists above and iterate — small, reliable builds scale best in a homelab.

Conclusion

Start small: build one temp/humidity node, connect it locally via MQTT, then add CO2 and a PIR alarm as needed. Focus on local processing, privacy-preserving sensors where appropriate, and reliable logging to scale a trusted homelab sensor network.