Cpp
// === Pin Definitions ===
// Communications
const int hc05Key    =  7;    // if used
// HC-05 serial is on Serial1 if you use a 328P–Arduino Nano
// (Arduino Nano only has one hardware UART, so we use SoftwareSerial if needed)
#include 
const int btRxPin    =  1;    // D1 → HC-05 RX 
const int btTxPin    =  0;    // D0 ← HC-05 TX
SoftwareSerial BT(btRxPin, btTxPin);

// Ultrasonic sensors
const int trigFront  =  7;    // D7 → HC-SR04 Front TRIG
const int echoFront  =  8;    // D8 ← HC-SR04 Front ECHO

// Bumper & status LED
const int bumpPin    = 13;    // D13 → bumper switch
const int ledPin     = 12;    // spare digital pin for LED_STAT (avoid sharing D13)

// MOSFET gates (test as digital outputs)
const int vacGate    = 10;    // D10 → Q1 gate
const int brushGate  = 11;    // D11 → Q2 gate
const int pumpGate   = 12;    // D12 → Q3/relay drive

// Motor driver inputs
const int m1In1      =  3;    // D3 → L293D IN1
const int m1In2      =  5;    // D5 → L293D IN2
const int m2In3      =  6;    // D6 → L293D IN3
const int m2In4      =  9;    // D9 → L293D IN4

// IR cliff sensors
const int ir1Pin     = A0;    // A0 → TCRT5000 #1
const int ir2Pin     = A1;    // A1 → TCRT5000 #2

// ========================

void setup() {
  Serial.begin(9600);
  BT.begin(9600);
  pinMode(ledPin,    OUTPUT);
  pinMode(bumpPin,   INPUT_PULLUP);
  pinMode(trigFront, OUTPUT);
  pinMode(echoFront, INPUT);
  
  pinMode(vacGate,   OUTPUT);
  pinMode(brushGate, OUTPUT);
  pinMode(pumpGate,  OUTPUT);

  pinMode(m1In1,     OUTPUT);
  pinMode(m1In2,     OUTPUT);
  pinMode(m2In3,     OUTPUT);
  pinMode(m2In4,     OUTPUT);

  Serial.println(F("=== Hardware Test Start ==="));
}

void loop() {
  // 1) Blink status LED
  digitalWrite(ledPin, HIGH);
  delay(200);
  digitalWrite(ledPin, LOW);
  delay(200);

  // 2) Read bumper switch
  bool bump = !digitalRead(bumpPin);
  Serial.print(F("Bumper: "));
  Serial.println(bump ? "PRESSED" : "OPEN");

  // 3) Test HC-05 comms
  if (BT.available()) {
    Serial.print(F("BT RX: "));
    Serial.write(BT.read());
  }
  if (Serial.available()) {
    BT.write(Serial.read());
    Serial.println(F("→ sent to HC-05"));
  }

  // 4) Trigger HC-SR04 Front
  long duration;
  digitalWrite(trigFront, LOW);
  delayMicroseconds(2);
  digitalWrite(trigFront, HIGH);
  delayMicroseconds(10);
  digitalWrite(trigFront, LOW);
  duration = pulseIn(echoFront, HIGH, 30000);
  float distCm = duration * 0.034 / 2;
  Serial.print(F("Front Dist: "));
  Serial.print(distCm);
  Serial.println(F(" cm"));

  // 5) Read IR cliff sensors
  int ir1 = analogRead(ir1Pin);
  int ir2 = analogRead(ir2Pin);
  Serial.print(F("IR1: "));
  Serial.print(ir1);
  Serial.print(F("  IR2: "));
  Serial.println(ir2);

  // 6) Toggle MOSFETs & relay
  digitalWrite(vacGate,   HIGH); delay(100); digitalWrite(vacGate,   LOW);
  digitalWrite(brushGate, HIGH); delay(100); digitalWrite(brushGate, LOW);
  digitalWrite(pumpGate,  HIGH); delay(100); digitalWrite(pumpGate,  LOW);
  Serial.println(F("MOSFET/Relay pulses sent"));

  // 7) Test motors via L293D (short bursts)
  digitalWrite(m1In1, HIGH);
  digitalWrite(m1In2, LOW);
  digitalWrite(m2In3, HIGH);
  digitalWrite(m2In4, LOW);
  delay(200);
  digitalWrite(m1In1, LOW);
  digitalWrite(m1In2, LOW);
  digitalWrite(m2In3, LOW);
  digitalWrite(m2In4, LOW);
  Serial.println(F("Motors forward pulse"));

  delay(1000);  // Wait before repeating
}

1. Upload this sketch to your Nano.
2. Open the Serial Monitor at 9600 baud.
3. Verify each printed message and sensor reading.
4. Observe LED blink, bumper switch state, ultrasonic distance, IR sensor values, MOSFET and motor pulses.