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

Project 3 — PIR Security Alarm with Raspberry Pi

Parts list

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

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 (push, SMS gateway, or a push service) or Home Assistant automations to notify on motion; pair with camera snapshots if desired but keep 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 any network services updated and avoid exposing device management ports directly to the internet
• Use local automations and encrypted MQTT to reduce attack surface

Data ingestion and logging

High-level choices for ingesting, storing, and analyzing sensor data in a homelab.

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 MQTT critical measurements to reduce data loss
• Tag messages with node IDs, sensor types, and timestamps to simplify parsing in Graylog or other log managers
• 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 place sensors near the items you care about rather than on the door
• Power: choose wired power for critical nodes (freezer alerts, CO2) and battery for flexible placement (bedrooms, closets)
• 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 low-bandwidth 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.

Start small: build one temp/humidity node, connect it to your local MQTT broker, then add a CO2 sensor and a PIR alarm. Iterate on placement, power, and logging, prioritize reliability and privacy, and scale gradually.