Vibration alerts¶

The supported haptic setup is a Vybronics VG0832022D 8mm LRA with a DRV2605L breakout. The actuator measures 8 × 3.25mm. Firmware and simulator controls are implemented; physical wiring, calibration, alert strength and power consumption still need bench validation.

Use this exact actuator profile. Other 8mm parts can have different voltage and frequency requirements. The manufacturer specifies 1.8Vrms at 235Hz. Hound starts conservatively at approximately 0.997Vrms with a 1.485V peak clamp to limit power and strength during initial testing. These are calculated settings, not measured outputs.

Keep the build inexpensive¶

Vibration is optional: the base Hound works with the display board and USB power alone. No haptics shield, extra microcontroller, speaker, battery or custom PCB is required for this feature. The incremental parts are one LRA, one DRV2605L breakout and short wires. Use solder pads rather than buying connector adapters where practical.

As a sourcing reference checked October 1, 2026, DigiKey lists the actuator at US$3.47 in single quantities. The Adafruit driver reference is US$7.95: about US$11.42 before wiring, tax and shipping for that combination. A less expensive DRV2605L module can reduce this, but its actual IC, decoupling and 3.3V wiring must be checked; it has not been qualified. Compare the delivered cost before ordering. The default profile does not require a premium actuator brand or branded breakout.

Controls¶

Open Settings → More: Display → More: Alerts → Sound and Vibration.

Enabling vibration starts a brief calibration that can buzz for about one second. Wait for DRV2605L: READY before testing. Calibration repeats when vibration is re-enabled and after boot if enabled in saved settings. It runs without waiting in the radio task. During calibration, alerts continue visually but haptic requests are dropped rather than queued.

Ordinary alerts use one click, or two for Strong detections, with a shared five-second cooldown. Travel Watch uses three clicks and may repeat once per minute while an eligible warning remains unacknowledged. These indicate Hound's confidence and repeated-presence heuristic, not proof of a surveillance device or movement. The on-screen click window previews timing; it is not a measurement of actual actuator motion.

Detector and alert-category switches, the confidence threshold, Ignore and Snooze apply to automatic vibration. Stop sniffing silences automatic vibration; touch cancels the current pattern. An unacknowledged Watch warning may vibrate again after its cooldown. With the display awake, holding BOOT for one second and releasing turns both sound and vibration off. Settings persist internally without an SD card. Synthetic demo detections never drive the physical actuator. The browser lab previews the same controls without vibrating the computer or phone.

Wiring¶

Power off and disconnect USB before wiring. Use a DRV2605L breakout with its required supply/REG capacitors and 3.3V-compatible I²C connections. The Hosyond E32R40T expansion header provides the following signals:

Both actuator leads go to the driver's differential outputs. Neither lead goes to ground, a GPIO, the speaker connector or a direct DC supply. Do not fit a flyback diode across an LRA. The driver supplies its alternating excitation.

The board schematic shows 10kΩ pull-ups to 3.3V on SDA and SCL. Breakout pull-ups must also go to 3.3V. Keep wires short; verify rise time if combining pull-ups or adding cable length. Hound owns this I²C bus at 100kHz and the driver's fixed 7-bit address, 0x5A. Additional I²C accessories are not covered by this integration.

Verify the board's regulator/USB headroom with Wi-Fi, display and SD active. Use a separate regulated 3.3V driver supply with common ground if needed; do not join two regulator outputs. Retain the breakout's decoupling, and keep the actuator's current return away from sensitive signal wiring. Mount the actuator securely to the enclosure and give its fine leads strain relief.

Driver behavior¶

The implementation follows TI's DRV2605L datasheet, sections 8.5 and 9.3. It selects closed-loop LRA operation and library 6, calibrates without programming OTP, and uses one finite on-chip click per pulse. It never selects continuous real-time playback. The register profile uses rated voltage 39, peak clamp 70, 300µs sampling and a 2.1ms initial half-period. Calibration has a 1.5-second software deadline. The chip completes each click independently of the UI.

The settings page reports NOT FOUND or an error if initialization, calibration or communication fails. No automatic retry loop runs against missing hardware: check wiring, turn vibration Off, then select the desired mode again. A separately reset driver is rejected if its voltage/LRA profile has reverted. Turning vibration off requests stop and standby. If communication is physically broken, Hound cannot confirm that command arrived; the previously started on-chip effect is finite.

Bench check before use¶

Fit the specified actuator and breakout, then verify that power-on with vibration Off stays quiet. Enable it, wait for READY, and test a single click. Check ordinary alerts, Strong detections, Watch, Ignore, Snooze, pause, BOOT mute and reboot. Confirm the saved mode returns and calibration completes.

Measure the differential output with suitable isolated/differential equipment; do not attach a grounded oscilloscope clip to either output. Verify voltage, temperature and supply stability in the final mounting. Check radio/SD operation during repeated alerts. Disconnect power if there is unexpected continuous vibration, heating or resets. Record the breakout revision, measurements and mounting before treating this feature as hardware validated.