Third Eye Kit, Node B: Lower Ranging (Shoes)
==============================================

MICROCONTROLLER: Arduino Mini Pro (5V)

LEFT SHOE SENSOR WIRING (HC-SR04 Ultrasonic):
────────────────────────────────────────────
  Sensor Pin | Arduino Pin | Function
  ─────────────────────────────────────
  VCC        | +5V         | Power (5V) [see NOTE below]
  GND        | GND         | Ground
  TRIG       | D9          | Trigger pulse
  ECHO       | D10         | Echo measurement

RIGHT SHOE SENSOR WIRING (HC-SR04 Ultrasonic):
───────────────────────────────────────────────
  Sensor Pin | Arduino Pin | Function
  ─────────────────────────────────────
  VCC        | +5V         | Power (5V) [see NOTE below]
  GND        | GND         | Ground
  TRIG       | D3          | Trigger pulse
  ECHO       | D4          | Echo measurement

HAPTIC FEEDBACK (Vibration Motors, left + right):
──────────────────────────────────────────────────
  Motor Pin       | Arduino Pin | Function
  ─────────────────────────────────────────
  Left Positive   | D5          | Control signal (PWM)
  Left Negative   | GND         | Ground
  Right Positive  | D6          | Control signal (PWM)
  Right Negative  | GND         | Ground

PASSIVE VISIBILITY (LDR + LED):
─────────────────────────────────
  Component  | Arduino Pin | Function
  ─────────────────────────────────────
  LDR        | A0          | Ambient light sensing (analog input)
  LED        | D7          | Passive visibility (digital output)
  GND        | GND         | Ground (shared)

POWER:
──────
  5V source (Arduino Mini Pro 5V variant per node_b.ino)
  Connected to Arduino RAW pin or USB power during development

FIRMWARE CONFIGURATION (node_b.ino):
────────────────────────────────────
  #define LEFT_TRIG      9      // Left shoe trigger pin
  #define LEFT_ECHO      10     // Left shoe echo pin
  #define RIGHT_TRIG     3      // Right shoe trigger pin
  #define RIGHT_ECHO     4      // Right shoe echo pin
  #define LEFT_HAPTIC    5      // Left haptic motor (PWM)
  #define RIGHT_HAPTIC   6      // Right haptic motor (PWM)
  #define LDR_PIN        A0     // Ambient light sensor (analog)
  #define LED_PIN        7      // Passive visibility LED
  #define ALERT_CM_LEFT  60     // Left alert distance in cm (TUNE PER USER)
  #define ALERT_CM_RIGHT 60     // Right alert distance in cm (TUNE PER USER)
  #define LED_THRESHOLD  300    // Ambient light threshold (0-1023 ADC)

TUNING NOTES:
─────────────
- ALERT_CM_LEFT / ALERT_CM_RIGHT typically range 50 to 60 cm depending on user's stride
- Start at 60 cm and adjust based on field testing
- LED_THRESHOLD (300) controls the ambient-light level at which the passive
  visibility LED turns on; adjust per typical deployment lighting
- Document final values in build log

TESTING:
────────
1. Upload firmware to Arduino Mini
2. Open Serial Monitor (9600 baud)
3. Sweep an obstacle (hand, book, curb edge) under each shoe sensor cone
4. Verify LEFT/RIGHT haptic motor activates when distance < ALERT_CM_LEFT/RIGHT
5. Cover the LDR to confirm the passive LED turns on below LED_THRESHOLD
6. Adjust ALERT_CM_LEFT/RIGHT until feedback distance feels natural for user

TROUBLESHOOTING:
─────────────────
- No haptic feedback: check LEFT_HAPTIC (D5) / RIGHT_HAPTIC (D6) wiring and motor driver
- Distance always 0: check HC-SR04 power and TRIG/ECHO pin connections (D9/D10 left, D3/D4 right)
- LED never lights: verify LDR wiring on A0 and LED_THRESHOLD against ambient conditions
- Erratic readings: sensor may be damaged; try spare HC-SR04

NOTE:
─────
- BUILD.md's Node B pinout section documents TRIG/ECHO/haptic/LDR/LED pin
  assignments but does not restate HC-SR04 VCC/GND wiring for this node.
  The VCC (+5V) / GND rows above follow the same HC-SR04 wiring pattern
  documented for Node A (node-a-pinout.txt) and the 5V platform stated in
  node_b.ino's header comment, not independently confirmed per-node in
  BUILD.md. Verify against your board before flashing.