PNX Technical Principles
From BLE handshake to micro-switch trigger: complete technical chain
BLE Handshake Flow
PNX Layer 1 (Identity Verification) completes device discovery, pairing, and UUID whitelist matching via standard BLE protocol.
- Module enters BLE broadcast state after power-on, broadcast interval recommended 100ms-500ms (configurable)
- After authorized phone approaches, user manually initiates system Bluetooth pairing
- After pairing completes, module records the phone's UUID to whitelist storage
- In subsequent use, module continuously scans whitelist UUIDs; upon successful match, establishes connection and enters Layer 1 verified state
- Module recommended to support 8-10 UUID whitelist entries for multi-user family scenarios
BLE Link Parameters
- Protocol: BLE 5.0+ (backward compatible with 4.2)
- Frequency: 2.400-2.4835 GHz (ISM band)
- TX Power: Adjustable, typical 0-8 dBm
- Link Encryption: AES-128, compliant with Bluetooth Core Spec 5.0
RSSI Distance Determination
Layer 2 (Presence Confirmation) continuously monitors verified phone's RSSI value, comparing with preset threshold to determine if user is within effective range.
RSSI Threshold Parameters (Recommended)
- Unlock threshold: -65dBm (adjustable range -40dBm to -90dBm)
- Lock threshold: -80dBm (adjustable range -55dBm to -95dBm)
- Hysteresis protection: Difference between unlock and lock thresholds recommended ≥ 15dBm to prevent repeated toggling at boundary
- Sampling period: 200ms-500ms, sliding average to reduce instantaneous fluctuation impact
Note: RSSI-to-physical-distance mapping is not absolute. In open ground -65dBm may correspond to 1.5m, but in underground garages may correspond to 1m or 2m. Thresholds should be calibrated via actual testing.
Micro-Switch Circuit
The core of Layer 3 (Execution Trigger) is the physical press signal from the micro-switch. This design transfers "execution control" from automatic system judgment to user physical action.
Micro-Switch Electrical Spec (Recommended)
- Voltage: DC 3.3V-12V (recommended 5V)
- Signal: Configurable as low-trigger (press to GND) or high-trigger (press to VCC)
- Debounce: ≥50ms (press) / ≥50ms (release), preventing mechanical contact bounce
- Response delay: From press to module detection, typical ≤20ms
- From press to vehicle control execution, typical delay ≤200ms
Security Mechanisms
Device Binding: UUID Whitelist
Module only responds to BLE connection requests from whitelist UUIDs. Whitelist is stored in module non-volatile memory, persisting across power cycles. Recommended maximum 8-10 UUID entries.
Communication Encryption
BLE link layer uses AES-128 encryption, compliant with Bluetooth Core Specification 5.0+. Key exchange during pairing follows standard BLE pairing flow.
Anti-Replay
Each critical communication includes timestamp and random nonce. Module validates:
- Time window: recommended ±30 seconds, commands outside window rejected
- Nonce uniqueness: Module records recently received nonce list, commands with duplicate nonce rejected
APP / Mini-Program API
Bluetooth Name Convention
Bluetooth broadcast name must be pure English or numeric combination, max 15 bytes, no Chinese characters, spaces, or special symbols.
Password Convention
Pairing password must be 6-digit numeric. Password changes written to non-volatile memory, recommended to take effect after module restart. Recovery method for forgotten password: short specific chip solder points for hardware reset.
Configurable Parameters
- Bluetooth broadcast name
- Pairing password
- Unlock/lock action mode (momentary / continuous)
- Unlock/lock momentary duration (milliseconds)
- Lock delay execution time (milliseconds)
- Bluetooth connection distance (1-15 levels)
- Unlock distance threshold (0-100)
- Lock distance threshold (0-100)
- Proximity mode switch (enable/disable)
Technical Parameters Quick Reference
| Protocol | BLE 5.0+ |
| Unlock Threshold | -65dBm |
| Lock Threshold | -80dBm |
| Switch Response Delay | ≤200ms |
| UUID Whitelist | 8-10 entries |
| Proximity Level | 6-8 (daily use) |