ECE Capstone · Spring 2026
Pulse.
Proximity-based social navigation device.
A dedicated, single-purpose device for spontaneous human connection.
CMU ECE · 18-500 · Spring 2026
problem & requirements
Smartphones engineer engagement, not connection.
The friction of opening an app, typing, coordinating, it kills spontaneity. Pulse removes that surface area entirely, then has to earn its place against the phone with measurable engineering targets.
Four use-case requirements mapped to engineering specs with explicit justification, the traceability matrix that anchors every downstream design decision.
system architecture
System architecture: device · firmware · server.
Custom PCB, 3D-printed shell, GNSS + IMU + radio + 1000mAh LiPo.
Step detection, PDR, Kalman fusion, UI state machine on ESP32-C5.
Node.js server, WebSocket routing, SQLite store, proximity engine.
firmware & state machine
Sensor-to-display pipeline, 200ms budget.
The end-to-end pipeline runs inside a single 200ms budget, from accelerometer sample to rendered arrow on the opposite device.
- Sensor read
- ≤ 5 ms
- Filter + PDR
- ≤ 15 ms
- WiFi round-trip
- ≤ 150 ms
- Render
- ≤ 25 ms
State transitions · per-state current draw
UI state machine
- OFF → power on
- CONNECTING → handshake w/ server
- ACTIVE → idle home screen
- NAVIGATING → live arrow loop
- IDLE → low-power hold
UI walkthrough
UI flow: idle → request → navigate → meetup.
Welcome
Send request
Waiting for response
Navigating
Success
testing & validation
Targets vs. measured results.
Nine metrics across latency, accuracy, endurance, and usability. Every spec passed; navigation update latency landed at ~140ms against a 200ms target.
risk mitigations
Failure modes and mitigations.
GPS occlusion
PDR fusion bridges signal gaps; Kalman weighting drops GNSS as HDOP rises.
Connection loss
Reconnect flow with state replay; in-flight meetups survive transient drops.
Power budget
IDLE state aggressively reclaimed by the state machine to extend session life.
final iteration
A compass that asks to be put down.
Pulse is a device with a single job, and a screen that quietly bows out when that job is done. It earns its place in your pocket by refusing to compete for your attention, and then disappears until the next time a friend is nearby.