PROJECT NEXARA AI HEAD - Master Release

PROJECT NEXARA AI HEAD - Master Release v1.6 / V3 Fixed

C.SWART | 2 SERVOS ONLY | 16-LED | STAR GROUND | ISOLATED POWER | NEXUS AI CORE™ | SA 🇿🇦

What is it?

An edge-AI animatronic head built from the ground up for low-cost humanoid robotics. Uses ESP32-CAM (AI-Thinker) as the vision brain, PCA9685 as the servo driver, MG995 13KG for Base Pan (CH0), SG90 9G Micro for Mask Tilt (CH1), and a 16-LED WS2812B ring for eye illumination & status feedback.

Why did I build it?

To create a robust, replicable AI head platform that solves common maker pitfalls: servo jitter, ground loops, and ESP32 brownout crashes. This V3 architecture implements a dedicated CENTRAL STAR GROUND and ISOLATED POWER distribution network.

How does it work?

- ESP32-CAM handles vision processing + servo logic

- I2C Control: SDA GPIO15 (Yellow) / SCL GPIO14 (Green) to PCA9685

- WS2812 NeoPixel Data: GPIO12 (Blue) with 330Ω inline resistor + 470µF rail cap + 10kΩ pull-down for safe boot

- Power Architecture: 7.4V LiPo -> Buck-Boost regulated to 5V 4A -> THICK RED heavy-gauge wire directly to PCA9685 V+ screw terminal. Logic powered via clean +5V breadboard rail. All grounds converge at one central star ground hub.

- Servos safely center on boot (90°), followed by a smooth pan sweep (40°-140°) with coordinated tilt and breathing blue LED ring activity.

Features (V1.6 Master Gold):

- 2-Servo streamlined architecture (high stability)

- Verified 16-LED count in left eye aperture

- Split pulse calibration: MG995 (120-620) / SG90 (150-600)

- Safe-boot logic: Green = Ready, Red = Error, Blue = Breathing

- Fully isolated high-current power rail (no servos drawing from ESP32 pins.

BOM - 12 PARTS VERIFIED:

1x ESP32-CAM AI-Thinker Module

1x PCA9685 16CH PWM Driver

1x MG995 13KG Metal Gear Servo (Base Pan - CH0)

1x SG90 9G Micro Servo (Mask Tilt - CH1)

1x 16-LED WS2812B NeoPixel Ring (Left Eye)

1x DC-DC Buck-Boost Converter 5V 4A Output

1x 7.4V LiPo Battery Pack

1x 470µF 16V Decoupling Capacitor

1x 330Ω Resistor (Data Line Protection)

1x 10kΩ Resistor (GPIO12 Safe-Boot Pull-down)

1x HKD Mini Breadboard + Ardu Proto Shield

1x C.SWART Hard Hat & Steampunk Gas Mask Chassis Assembly

Build Instructions:

1. Calibrate Buck-Boost output to EXACTLY 5.0V using a multimeter before connecting logic boards.

2. Wire per V3 Master Diagram: GPIO14 -> SCL, GPIO15 -> SDA, GPIO12 -> DI (via 330Ω resistor). Wire PCA9685 VCC and ESP32 5V to the +5V logic rail. Wire thick heavy-gauge red wire from Buck-Boost OUT+ directly to PCA9685 V+ screw terminal.

3. Centralize Star Ground: Connect Buck-Boost OUT-, PCA9685 GND, ESP32 GND, NeoPixel GND, and Battery IN- to a single star ground point.

4. Libraries Required: Adafruit PWM Servo Driver, Adafruit NeoPixel, and ESP32 Board Manager v2.0.14.

5. Flash Master Release v1.6 code (Select board: "AI Thinker ESP32-CAM", Partition: "Huge APP 3MB").

Files Included:

- V3 Master Wiring Diagram (Isolated Power & Star Ground)

- V1.6 Master Ensemble Sheet (Exploded Assembly & BOM)

- Master Release v1.6 C++ INO Code

Cpp

#include <Wire.h>

#include <Adafruit_PWMServoDriver.h>

#include <Adafruit_NeoPixel.h>

#include "esp_camera.h"

// ===== PROJECT NEXARA AI HEAD - MASTER RELEASE v1.6 / V3 Fixed =====

// C.SWART Hard Hat - 2 SERVOS ONLY - 16-LED - STAR GROUND - ISOLATED POWER

// PIN DEFINITIONS - V3/V4 WIRING MATCH

#define I2C_SDA 15     // Yellow -> PCA9685 SDA

#define I2C_SCL 14     // Green -> PCA9685 SCL

#define LED_PIN 12     // Blue -> WS2812 DI

#define LED_COUNT 16    // 16-LED ring confirmed

// PCA9685 channels - 2 SERVOS ONLY

#define SERVO_PAN  0    // MG995 13KG - Base Pan - CH0

#define SERVO_TILT 1    // SG90 9G Micro - Mask Tilt - CH1

// Servo pulse limits

#define MG995_MIN 120

#define MG995_MAX 620

#define SG90_MIN  150

#define SG90_MAX  600

Adafruit_PWMServoDriver pwm = Adafruit_PWMServoDriver(0x40);

Adafruit_NeoPixel ring(LED_COUNT, LED_PIN, NEO_GRB + NEO_KHZ800);

void setServo(uint8_t ch, int angle) {

 angle = constrain(angle, 0, 180);

 uint16_t pulse;

 if (ch == SERVO_PAN) {

  pulse = map(angle, 0, 180, MG995_MIN, MG995_MAX);

 } else {

  pulse = map(angle, 0, 180, SG90_MIN, SG90_MAX);

 }

 pwm.setPWM(ch, 0, pulse);

}

void centerServos() {

 setServo(SERVO_PAN, 90);  // Center pan

 setServo(SERVO_TILT, 90); // Center tilt

}

void setRingColor(uint8_t r, uint8_t g, uint8_t b) {

 for (int i = 0; i < LED_COUNT; i++) ring.setPixelColor(i, ring.Color(r, g, b));

 ring.show();

}

void breatheBlue(int speed = 12) {

 static int brightness = 0;

 static int direction = 1;

 brightness += direction;

 if (brightness >= 255 || brightness <= 0) direction = -direction;

 setRingColor(0, 0, brightness);

 delay(speed);

}

void setup() {

 Serial.begin(115200);

 delay(500);

 Serial.println("\nPROJECT NEXARA AI HEAD v1.6 - C.SWART - 2 SERVO - 16-LED - NEXUS AI CORE");

 Wire.begin(I2C_SDA, I2C_SCL);

 pwm.begin();

 pwm.setPWMFreq(50); // 50Hz for analog servos

 delay(10);

 // Safe-boot - star ground + 10k pulldown protection

 centerServos();

 ring.begin();

 ring.setBrightness(80);

 setRingColor(0, 0, 40); // Dim blue = booting

 // Camera init - AI-Thinker

 camera_config_t config;

 config.ledc_channel = LEDC_CHANNEL_0;

 config.ledc_timer = LEDC_TIMER_0;

 config.pin_d0 = 5; config.pin_d1 = 18; config.pin_d2 = 19; config.pin_d3 = 21;

 config.pin_d4 = 36; config.pin_d5 = 39; config.pin_d6 = 34; config.pin_d7 = 35;

 config.pin_xclk = 0; config.pin_pclk = 22; config.pin_vsync = 25;

 config.pin_href = 23; config.pin_sscb_sda = 26; config.pin_sscb_scl = 27;

 config.pin_pwdn = 32; config.pin_reset = -1;

 config.xclk_freq_hz = 20000000;

 config.pixel_format = PIXFORMAT_JPEG;

 config.frame_size = FRAMESIZE_VGA;

 config.jpeg_quality = 12;

 config.fb_count = 1;

 if (esp_camera_init(&config) != ESP_OK) {

  Serial.println("Camera init failed");

  setRingColor(80, 0, 0); // Solid Red = Error

  return;

 }

 Serial.println("Nexara AI Head Ready!");

 setRingColor(0, 80, 0);  // Solid Green = System Ready

 delay(500);

}

void loop() {

 static int pan = 90;

 static int dir = 1;

 // Pan sweep sequence

 pan += dir;

 if (pan >= 140 || pan <= 40) dir = -dir;

 setServo(SERVO_PAN, pan);

 setServo(SERVO_TILT, 90 + (pan - 90) / 4); // Slight synchronized tilt

 breatheBlue(12);

 delay(20);

}

Best regards,

Coenraad Swart

Founder & Lead Architect | Nexus AI Core (Pty) Ltd

Polokwane, South Africa

+27 834011107