5 + 1 bonus Elite-Tier Microcontroller Engineering Blueprints
System Architecture: Master-Slave array sharing data over an isolated I2C bus channel. The dual Arduinos isolate high-frequency local hardware telemetry reading and relay switching arrays, while the dual ESP32 cores process secure dual-band Wi-Fi packet uploads, IoT database synchronization, and encrypted override command scripts.
Bus Map: Uno-1 (Sensor Node) & Uno-2 (Actuator Controller) connect as Slaves to ESP32 Master-1 via hardware SDA/SCL lines with 4.7k Pull-up Resistors.
#include <Wire.h>
#include <WiFi.h>
// Distributed Master Control Core
void setup() {
Wire.begin(21, 22); // Custom SDA, SCL pins
WiFi.begin("RikMakersNet", "SecurePass123");
}
void loop() {
Wire.requestFrom(8, 6); // Request sensor telemetry packet from Uno Slave 8
// Fast loop network processing routine...
}Sensors to D2-D3, D11-D12, A0-A1. Motors to Shield M1-M4.
#include
// Maze Dimensions
const int SIZE = 5;
int maze[SIZE][SIZE];
int walls[SIZE][SIZE]; // Bitmask: 1=North, 2=East, 4=South, 8=West
// Robot State
int x = 0, y = 0; // Current position
int dir = 0; // 0:North, 1:East, 2:South, 3:West
// Pin Definitions
#define TRIG_F 2
#define ECHO_F 3
// ... Define other sensors and motor pins ...
void setup() {
Serial.begin(9600);
initializeMaze();
}
void loop() {
updateWalls(); // Check sensors for walls
floodFill(2, 2); // Goal is cell (2,2)
moveToBestCell(); // Determine next move based on lowest neighboring value
}
// 1. Initialize maze with distances to goal (Manhattan distance)
void initializeMaze() {
for (int i = 0; i < SIZE; i++) {
for (int j = 0; j < SIZE; j++) {
maze[i][j] = abs(i - 2) + abs(j - 2);
}
}
}
// 2. Flood Fill logic to update cell values
void floodFill(int targetX, int targetY) {
// Simple version: Iteratively update cell values based on neighbors
bool changed = true;
while (changed) {
changed = false;
for (int i = 0; i < SIZE; i++) {
for (int j = 0; j < SIZE; j++) {
if (i == targetX && j == targetY) continue;
int minDist = 255;
// Check North (if no wall)
if (!(walls[i][j] & 1) && i > 0) minDist = min(minDist, maze[i-1][j]);
// ... Check East, South, West ...
if (maze[i][j] != minDist + 1) {
maze[i][j] = minDist + 1;
changed = true;
}
}
}
}
}
// 3. Movement logic
void moveToBestCell() {
// Check neighbors, find smallest value in 'maze' array, and command motors
}
RFID SPI to D13-D9. Keypad to D8-D1. LCD via I2C.
#include
#include
#include
#include
#include
#include
#include
// --- Configuration ---
const byte ROWS = 4;
const byte COLS = 4;
char hexaKeys[ROWS][COLS] = {
{'1', '2', '3', 'A'},
{'4', '5', '6', 'B'},
{'7', '8', '9', 'C'},
{'*', '0', '#', 'D'}
};
byte rowPins[ROWS] = {2, 3, 4, 5};
byte colPins[COLS] = {6, 7, 8, 9};
Keypad customKeypad = Keypad(makeKeymap(hexaKeys), rowPins, colPins, ROWS, COLS);
Servo lockServo;
LiquidCrystal_I2C lcd(0x27, 16, 2);
// Master override code (Layer 2)
const char* masterCode = "A1234";
char inputBuffer[10];
byte bufferIndex = 0;
bool isAdminMode = false;
// EEPROM addresses
const int HASH_START_ADDR = 0;
const int HASH_LENGTH = 32; // SHA-256 produces 32 bytes
void setup() {
Serial.begin(9600);
lockServo.attach(10);
lockServo.write(0); // Locked position
lcd.init();
lcd.backlight();
lcd.setCursor(0, 0);
lcd.print("System Ready");
delay(1000);
lcd.clear();
}
void loop() {
char customKey = customKeypad.getKey();
if (customKey) {
handleKeyPress(customKey);
}
}
void handleKeyPress(char key) {
if (key == '#') { // Enter key
inputBuffer[bufferIndex] = '\0';
processInput();
bufferIndex = 0;
} else if (key == '*') { // Clear key
bufferIndex = 0;
lcd.clear();
lcd.print("Enter Pin:");
} else {
inputBuffer[bufferIndex] = key;
lcd.setCursor(bufferIndex, 1);
lcd.print('*');
bufferIndex++;
}
}
void processInput() {
// Check for Layer 2: Administrator Override
if (strcmp(inputBuffer, masterCode) == 0) {
isAdminMode = true;
lcd.clear();
lcd.print("Admin Mode");
delay(1000);
lcd.print("New Pin:");
bufferIndex = 0;
return;
}
if (isAdminMode) {
saveNewPassword(inputBuffer);
isAdminMode = false;
lcd.clear();
lcd.print("Pin Updated!");
delay(1000);
lcd.clear();
} else {
// Check for Layer 1: User Authentication
if (verifyPassword(inputBuffer)) {
lcd.clear();
lcd.print("Access Granted");
lockServo.write(90); // Unlock
delay(5000);
lockServo.write(0); // Lock
lcd.clear();
} else {
lcd.clear();
lcd.print("Access Denied");
delay(1000);
lcd.clear();
}
}
}
bool verifyPassword(char* inputPass) {
byte inputHash[HASH_LENGTH];
computeHash(inputPass, inputHash);
// Compare input hash with stored hash in EEPROM
for (int i = 0; i < HASH_LENGTH; i++) {
if (EEPROM.read(HASH_START_ADDR + i) != inputHash[i]) {
return false;
}
}
return true;
}
void saveNewPassword(char* newPass) {
byte newHash[HASH_LENGTH];
computeHash(newPass, newHash);
// Save the new hash to EEPROM
for (int i = 0; i < HASH_LENGTH; i++) {
EEPROM.update(HASH_START_ADDR + i, newHash[i]);
}
}
void computeHash(const char* input, byte* output) {
SHA256 sha256;
sha256.update((uint8_t*)input, strlen(input));
sha256.finalize(output, HASH_LENGTH);
}
AS608 TX/RX to D2/D3. Relay to D4.
#include
#include
// Define pins for the fingerprint sensor
SoftwareSerial mySerial(2, 3); // RX, TX
Adafruit_Fingerprint finger = Adafruit_Fingerprint(&mySerial);
const int relayPin = 4; // Pin to trigger the ignition relay
void setup() {
Serial.begin(9600);
while (!Serial);
delay(100);
Serial.println("\n\nBiometric Vehicle Ignition System Initializing...");
// Set the data rate for the sensor serial port
finger.begin(57600);
if (finger.verifyPassword()) {
Serial.println("Found fingerprint sensor!");
} else {
Serial.println("Did not find fingerprint sensor :(");
while (1) { delay(1); }
}
pinMode(relayPin, OUTPUT);
digitalWrite(relayPin, HIGH); // Set HIGH to ensure relay is off (if using Active LOW relay module)
}
void loop() {
getFingerprintIDez();
delay(50); // Don't ned to run this at full speed
}
int getFingerprintIDez() {
uint8_t p = finger.getImage();
if (p != FINGERPRINT_OK) return -1;
p = finger.image2Tz();
if (p != FINGERPRINT_OK) return -1;
p = finger.fingerFastSearch();
if (p != FINGERPRINT_OK) {
Serial.println("Fingerprint not found! Access Denied.");
return -1;
}
// Found a match!
Serial.print("Found ID #"); Serial.print(finger.fingerID);
Serial.print(" with confidence of "); Serial.println(finger.confidence);
// Trigger the ignition
Serial.println("Vehicle Started!");
digitalWrite(relayPin, LOW); // Turn ON the ignition relay (Assuming Active-LOW)
delay(3000); // Keep ignition engaged/on for 3 seconds (adjust as needed)
digitalWrite(relayPin, HIGH); // Turn OFF relay after simulated start
Serial.println("Ignition turned off. Drive safely.");
return finger.fingerID;
}
INA219 to A5/A4. SD Card via SPI (D13, D12, D11, D4).
#include
#include
// --- Configurable Settings ---
int tolerance = 10; // LDR reading difference tolerance to prevent jitter
int stepSize = 1; // Degrees to move servo on each check
// --- Pin Definitions ---
const int ldrTopPin = A0;
const int ldrBottomPin = A1;
const int ldrLeftPin = A2;
const int ldrRightPin = A3;
Servo servoVertical;
Servo servoHorizontal;
// Starting angles for the servos
int posVertical = 90;
int posHorizontal = 90;
void setup() {
servoVertical.attach(9);
servoHorizontal.attach(10);
// Set servos to center position on boot
servoVertical.write(posVertical);
servoHorizontal.write(posHorizontal);
delay(500);
}
void loop() {
// 1. WAKE UP & TRACK SUN
trackSun();
// 2. LOG DATA (Add your SD logging or EEPROM write functions here)
logData();
// 3. DEEP SLEEP (Approx. 1 minute)
// Watchdog timer max is 8s, so we loop it 8 times (8s * 7.5 = 60s)
for (int i = 0; i < 8; i++) {
LowPower.powerDown(SLEEP_8S, ADC_OFF, BOD_OFF);
}
}
void trackSun() {
int top = analogRead(ldrTopPin);
int bottom = analogRead(ldrBottomPin);
int left = analogRead(ldrLeftPin);
int right = analogRead(ldrRightPin);
// Calculate averages
int avgVert = (top + bottom) / 2;
int avgHoriz = (left + right) / 2;
// --- VERTICAL AXIS CONTROL ---
if (abs(top - bottom) > tolerance) {
if (top > bottom) {
posVertical += stepSize;
} else {
posVertical -= stepSize;
}
}
// --- HORIZONTAL AXIS CONTROL ---
if (abs(left - right) > tolerance) {
if (left > right) {
posHorizontal -= stepSize; // Reverse as needed depending on LDR orientation
} else {
posHorizontal += stepSize;
}
}
// Constrain servo limits
posVertical = constrain(posVertical, 0, 180);
posHorizontal = constrain(posHorizontal, 0, 180);
// Apply positions
servoVertical.write(posVertical);
servoHorizontal.write(posHorizontal);
// Small delay for servos to reach position before sleeping
delay(15);
}
void logData() {
// Placeholder for logger function.
// Disable low power configurations briefly if needed.
}
PCA9685 to 21/22. Servos to PCA9685 channels 0-3.
#include
#include
#include
#include
#include
#include
// --- BLE UUIDs ---
#define SERVICE_UUID "6E400001-B5A3-F393-E0A9-E50E24DCCA9E" // UART standard for simple TX/RX
#define CHARACTERISTIC_UUID_RX "6E400002-B5A3-F393-E0A9-E50E24DCCA9E"
#define CHARACTERISTIC_UUID_TX "6E400003-B5A3-F393-E0A9-E50E24DCCA9E"
// --- Pin Definitions for Servos ---
const int servoPins[4] = {13, 12, 14, 27}; // Base, Shoulder, Elbow, Gripper
Servo servos[4];
BLECharacteristic *pTxCharacteristic;
bool deviceConnected = false;
// --- Low-Latency BLE Callbacks ---
class MyServerCallbacks: public BLEServerCallbacks {
void onConnect(BLEServer* pServer) {
deviceConnected = true;
// Request lower connection latency (min 10ms, max 20ms) for high-speed, real-time control
pServer->updateConnParams(pServer->getConnId(), 8, 16, 0, 400);
};
void onDisconnect(BLEServer* pServer) {
deviceConnected = false;
}
};
class MyCallbacks: public BLECharacteristicCallbacks {
void onWrite(BLECharacteristic *pCharacteristic) {
std::string rxValue = pCharacteristic->getValue();
if (rxValue.length() > 0) {
// Parse incoming CSV string (e.g., "90,45,120,30")
// Note: For production use, consider sending byte arrays instead of strings to cut down latency further.
int angles[4];
int index = 0;
char *token = strtok((char*)rxValue.c_str(), ",");
while (token != NULL && index < 4) {
angles[index++] = atoi(token);
token = strtok(NULL, ",");
}
// Apply constraints & move servos
for (int i = 0; i < 4; i++) {
if(angles[i] >= 0 && angles[i] <= 180) {
servos[i].write(angles[i]);
}
}
}
}
};
void setup() {
Serial.begin(115200);
// Attach Servos
for(int i = 0; i < 4; i++) {
servos[i].setPeriodHertz(50);
servos[i].attach(servoPins[i], 500, 2400); // Standard micro-servo range (500-2400us)
}
// Initialize BLE
BLEDevice::init("ESP32_Robot_Arm");
BLEServer *pServer = BLEDevice::createServer();
pServer->setCallbacks(new MyServerCallbacks());
BLEService *pService = pServer->createService(SERVICE_UUID);
pTxCharacteristic = pService->createCharacteristic(
CHARACTERISTIC_UUID_TX,
BLECharacteristic::PROPERTY_NOTIFY
);
pTxCharacteristic->addDescriptor(new BLE2902());
BLECharacteristic *pRxCharacteristic = pService->createCharacteristic(
CHARACTERISTIC_UUID_RX,
BLECharacteristic::PROPERTY_WRITE
);
pRxCharacteristic->setCallbacks(new MyCallbacks());
pService->start();
// Start Advertising
BLEAdvertising *pAdvertising = BLEDevice::getAdvertising();
pAdvertising->addServiceUUID(SERVICE_UUID);
pAdvertising->setScanResponse(true);
pAdvertising->setMinPreferred(0x06); // functions that help with low-latency connection settings
pAdvertising->setMinPreferred(0x12);
BLEDevice::startAdvertising();
Serial.println("Waiting a client connection to notify...");
}
void loop() {
// Bluetooth connection handles all processing in the callback, keep loop clear for IK logic
// To send sensor feedback to your app (like live encoder angles), you can use:
// pTxCharacteristic->setValue(String(current_angle));
// pTxCharacteristic->notify();
delay(10);
}