Calibration evidence stored
Readiness can be presented with the relevant state and calibration evidence before the instructor begins training.
System architecture
Local-first from sensor to session review
A verified view of how ResQ turns physical chest compressions into live, understandable training feedback.
Architecture layers
One system, seven clear responsibilities
Each layer can be inspected and tested independently while participating in a single local training workflow.
Mechanical & sensing
Soft chest overlay, pneumatic bladder concept, pressure channels, Hall-effect displacement sensing, physical controls.
Pressure + magnetic sensingEmbedded firmware
Sensor acquisition, calibration, CPR metrics, persistent configuration, state transitions, telemetry, fault recovery.
ESP32-C3 · ESP-IDF · FreeRTOSLocal messaging
Status, heartbeat, telemetry, events, calibration evidence, and commands use the canonical resq/{deviceId}/... namespace.
Backend
Device registration, readiness, session lifecycle, telemetry processing, scoring, user access, streaming, and exports.
Java · Spring BootPersistence
Local device, calibration, user, session, score, and synchronization-queue records.
SQLiteDesktop & dashboards
Windows service orchestration plus responsive instructor and trainee experiences delivered through REST and SSE.
Tauri · Rust · React · TypeScriptOptional cloud
Queued synchronization is isolated from live training so internet or cloud failure does not interrupt a local session.
Under Active DevelopmentData path
Physical action becomes local feedback
Real-time data stays close to the training station; only optional synchronization crosses the local boundary.
InputCPR compression
→
SensingPressure + displacement
→
EmbeddedMetrics + state
→
MessagingLocal MQTT
→
ApplicationProcess + persist
→
ExperienceLive SSE dashboard
Firmware state machine
Explicit states for a recoverable device
State names below are taken from the production firmware. Error, interruption, reset, and shutdown paths are part of the implementation—not decorative diagram branches.
BOOT
CONFIG_CHECK
PROVISIONING
WIFI_CONNECTING
BACKEND_REGISTERING
MQTT_CONNECTING
PAIRED_IDLE
CALIBRATING
CALIBRATION_FAIL
READY_FOR_SESSION
SESSION_ACTIVE
SESSION_INTERRUPTED
ERROR
RESETTING
TURN_OFF
Normal operation progresses through configuration and connectivity into idle, calibration, readiness, and active-session states. Failure and recovery transitions depend on the triggering condition.
Calibration & readiness
Evidence before assessment
ResQ does not treat “connected” as automatically ready. The device and sensors must pass the supported calibration workflow before a scored session starts.
01Device connected
→
02Sensor check
→
03Rest baseline
→
04Compression reference
→
05Pressure validation
→
PassReady for session
Reason and recovery action shown
Correct the physical setup or sensor condition, then retry. A failed readiness check does not silently continue into scoring.
CPR metrics
Focused measurements, understandable coaching
Institution-specific target ranges remain configurable. The website does not claim universal clinical thresholds or certification.
Compression depth
Displacement estimates derived from calibrated sensor input.
Compression rate
Timing-derived cadence calculated throughout an active session.
Full recoil
Per-cycle detection of whether the chest returns sufficiently between compressions.
Pause time
Interruptions and periods without valid compressions are tracked.
Hand placement & balance
Pressure distribution supports coaching around left/right loading.
Session summary
Completed sessions combine metric performance into reviewable results.
MQTT contract
A single canonical topic namespace
Historical documentation used two patterns. Production firmware uses resq/{deviceId}/...; the LocalHub retains compatibility parsing for older topics but does not make them canonical.
status
Retained device state and readiness information.
heartbeat
Connectivity and health cadence for live device presence.
telemetry
Active sensor and CPR metric samples.
events
Session, calibration, and error events.
cmd/...
Backend-to-firmware actions with request correlation.
debug
Diagnostic information for controlled development workflows.
Local-first resilience
The physical prototype stays connected to a local training loop
The instructor machine hosts every time-sensitive component: broker, backend, database, and dashboards. Internet or cloud failure cannot interrupt a local session.
Implemented
Local sessions, scoring, history, and LAN dashboard access.
Under Active Development
Optional long-term cloud synchronization and remote aggregation.
Continue exploring
Development statusSee how the architecture became a working product
Follow the implementation, test evidence, releases, and remaining roadmap.