🌸 BLOOMING 80085 SPEC — HUSHBELL

1. What: A doorbell that rings at frequencies only humans can hear, completely silent to dogs.
2. Who: Every dog owner who has lost their mind watching their dog lose its mind every time someone rings the doorbell.
3. Why: Because the UPS driver shouldn't trigger a Code Red in your living room.

1. Input: Visitor presses doorbell button.
2. Parse: Circuit activates tone generator with frequency-filtered output.
3. Process: Speaker emits tone in the 2,000-3,000 Hz sweet spot - peak human hearing sensitivity, within the range dogs find least alerting. Alternatively: modulated low-frequency tone below 100 Hz that humans perceive as a hum/vibration but falls below the dog startle threshold.
4. Output: Human hears doorbell. Dog does not react.
5. Feedback: Did the dog bark? No? Ship it. Yes? Adjust frequency.

HUMAN HEARING:    20 Hz – 20,000 Hz
DOG HEARING:      67 Hz – 45,000 Hz

OVERLAP:          67 Hz – 20,000 Hz (both hear this)
HUMAN ONLY:       20 Hz – 67 Hz (below dog range)

STRATEGY A — GO LOW:
  Tone at 30-50 Hz.
  Humans hear/feel it as a low hum or vibration.
  Dogs can't hear below ~67 Hz.
  Problem: low frequencies need big speakers
  and don't "sound like a doorbell."
  Solution: pair with LED flash or phone notification.
  The sound is the alert. The light confirms.

STRATEGY B — PSYCHOACOUSTIC:
  Dogs don't just HEAR differently.
  They REACT differently.
  Dog startle response is triggered by:
    - sudden onset (sharp attack)
    - high frequency (>3,000 Hz)
    - high amplitude (loud)

  A tone that is:
    - gradual onset (slow fade-in over 500ms)
    - mid frequency (1,500-2,500 Hz)
    - moderate amplitude (60 dB, conversational)

  ...is AUDIBLE to dogs but does NOT trigger
  the startle/bark response.

  The dog hears it. The dog doesn't care.

  This is the more practical approach:
  not INAUDIBLE to dogs, but UNREMARKABLE to dogs.

STRATEGY C — HYBRID:
  Primary: 40 Hz sub-bass pulse (below dog range)
  Secondary: phone push notification via WiFi
  Tertiary: LED strip flash at front door
  No audible mid-range tone at all.
  Dog hears nothing. Sees a light. Doesn't care.
  Human feels the hum + gets phone buzz + sees light.

"This doorbell alerts humans but refuses to alert dogs, and that refusal is the product."

Every other doorbell is designed for maximum human attention. Maximum attention = maximum startle = maximum dog response. HUSHBELL is designed for minimum startle that still gets a human to the door. The constraint is the innovation.

"If this disappeared, every dog owner goes back to the daily ritual of: doorbell rings → dog explodes → owner screams at dog → visitor stands awkwardly → dog keeps barking → owner opens door while restraining 70 lbs of pure acoustic fury → visitor says 'oh he's friendly!' → owner contemplates the void."

HUSHBELL gives that family peace. The dog stays calm. The owner stays calm. The visitor doesn't get tackled. The marriage survives one more delivery.

OPTION A — DUMB VERSION ($15):
  ESP32                        $3.50
  Tactile transducer (bass)    $8.00  (makes surface vibrate at 40 Hz)
  Momentary push button        $0.50  (the doorbell button)
  3.7V LiPo + charger         $4.50
  Enclosure (3D printed)       $1.00
  TOTAL:                       $17.50

  Mount tactile transducer on door frame.
  Press button → ESP32 drives transducer at 40 Hz.
  Human feels the door frame hum.
  Dog hears nothing.

OPTION B — SMART VERSION ($25):
  Everything in Option A        $17.50
  + WiFi push notification      $0 (ESP32 has WiFi)
  + WS2812B LED strip (4 LEDs) $1.00
  + Piezo buzzer at 2kHz        $0.30 (optional, slow fade-in)
  + MQTT integration            $0 (software)
  TOTAL:                        $18.80

  Press button → ESP32 sends:
    1. 40 Hz pulse to transducer (feel it)
    2. Push notification to phone (see it)
    3. LED flash at door (visual confirm)
    4. Optional: 2kHz tone with 500ms fade-in (hear it, dog ignores it)

OPTION C — FULL FARTS INTEGRATION ($20):
  Use F.A.R.T.S. ESP32 template.
  Swap actuators/fart.h → actuators/hushbell.h
  Same firmware. Same MQTT. Same fleet management.
  Now your doorbell is part of your robot fleet.
  Because why not.

// actuators/hushbell.h
#define TRANSDUCER_PIN 12
#define LED_PIN 4
#define BUZZER_PIN 25

void actuator_init() {
  pinMode(TRANSDUCER_PIN, OUTPUT);
  ledcSetup(0, 40, 8);          // 40 Hz, 8-bit resolution
  ledcAttachPin(TRANSDUCER_PIN, 0);
  ledcSetup(1, 2000, 8);        // 2kHz for optional tone
  ledcAttachPin(BUZZER_PIN, 1);
}

void actuator_fire(String params) {
  // Sub-bass pulse: 40 Hz for 3 seconds
  ledcWrite(0, 200);

  // Optional gentle tone: fade in over 500ms
  for (int vol = 0; vol < 128; vol += 2) {
    ledcWrite(1, vol);
    delay(8);                    // 500ms total fade-in
  }

  // Hold for 2 seconds
  delay(2000);

  // Fade out
  for (int vol = 128; vol > 0; vol -= 2) {
    ledcWrite(1, vol);
    delay(8);
  }

  ledcWrite(0, 0);
  ledcWrite(1, 0);

  // Send push notification via MQTT
  // mqtt.publish("home/doorbell/ring", "SOMEONE_AT_DOOR");
}