From 0cd36d280993896133aec4ebf6ca43bfdef254d8 Mon Sep 17 00:00:00 2001
From: "@dev.mako" <prinz.jewel11@gmail.com>
Date: Wed, 29 Jul 2026 10:14:50 +0800
Subject: [PATCH 1/4] refactor: make all interactive sketches non-blocking

---
 .../exercise_a_arrow_controller.ino           |  93 +++---
 .../exercise_b_multi_led_pattern.ino          | 168 +++++-----
 .../exercise_c_smart_fan.ino                  | 105 ++++---
 .../exercise_d_wheel_simulation.ino           | 165 +++++-----
 .../exercise_e_knight_rider_motor_sync.ino    | 108 +++----
 .../exercise_f_full_system_integration.ino    | 296 +++++++++++-------
 .../basic_bluetooth_led.ino                   |  31 +-
 7 files changed, 497 insertions(+), 469 deletions(-)

diff --git a/exercises/exercise-a-arrow-controller/exercise_a_arrow_controller.ino b/exercises/exercise-a-arrow-controller/exercise_a_arrow_controller.ino
index 319b333..0a17196 100644
--- a/exercises/exercise-a-arrow-controller/exercise_a_arrow_controller.ino
+++ b/exercises/exercise-a-arrow-controller/exercise_a_arrow_controller.ino
@@ -1,55 +1,62 @@
-const int ledUp = 2;
-const int ledLeft = 3;
-const int ledRight = 4;
-const int ledDown = 5;
+constexpr uint8_t kLedUp = 2;
+constexpr uint8_t kLedLeft = 3;
+constexpr uint8_t kLedRight = 4;
+constexpr uint8_t kLedDown = 5;
 
-char btCommand = 'X';
+char currentCommand = 'X';
+
+void writeDirection(bool up, bool left, bool right, bool down) {
+  digitalWrite(kLedUp, up ? HIGH : LOW);
+  digitalWrite(kLedLeft, left ? HIGH : LOW);
+  digitalWrite(kLedRight, right ? HIGH : LOW);
+  digitalWrite(kLedDown, down ? HIGH : LOW);
+}
+
+void applyCommand(char command) {
+  switch (command) {
+    case 'Q':
+      writeDirection(true, true, false, false);
+      Serial.println(F("Direction: UP-LEFT"));
+      break;
+    case 'E':
+      writeDirection(true, false, true, false);
+      Serial.println(F("Direction: UP-RIGHT"));
+      break;
+    case 'Z':
+      writeDirection(false, true, false, true);
+      Serial.println(F("Direction: DOWN-LEFT"));
+      break;
+    case 'C':
+      writeDirection(false, false, true, true);
+      Serial.println(F("Direction: DOWN-RIGHT"));
+      break;
+    default:
+      currentCommand = 'X';
+      writeDirection(false, false, false, false);
+      Serial.println(F("Direction: OFF"));
+      break;
+  }
+}
 
 void setup() {
   Serial.begin(9600);
-
-  pinMode(ledUp, OUTPUT);
-  pinMode(ledLeft, OUTPUT);
-  pinMode(ledRight, OUTPUT);
-  pinMode(ledDown, OUTPUT);
+  pinMode(kLedUp, OUTPUT);
+  pinMode(kLedLeft, OUTPUT);
+  pinMode(kLedRight, OUTPUT);
+  pinMode(kLedDown, OUTPUT);
+  applyCommand(currentCommand);
 }
 
 void loop() {
-  if (Serial.available() > 0) {
-    btCommand = Serial.read();
+  if (Serial.available() == 0) {
+    return;
   }
 
-  if (btCommand == 'Q') {
-    digitalWrite(ledUp, HIGH);
-    digitalWrite(ledLeft, HIGH);
-    digitalWrite(ledRight, LOW);
-    digitalWrite(ledDown, LOW);
-    Serial.println("Up-Left");
-  } else if (btCommand == 'E') {
-    digitalWrite(ledUp, HIGH);
-    digitalWrite(ledLeft, LOW);
-    digitalWrite(ledRight, HIGH);
-    digitalWrite(ledDown, LOW);
-    Serial.println("Up-Right");
-  } else if (btCommand == 'Z') {
-    digitalWrite(ledUp, LOW);
-    digitalWrite(ledLeft, HIGH);
-    digitalWrite(ledRight, LOW);
-    digitalWrite(ledDown, HIGH);
-    Serial.println("Down-Left");
-  } else if (btCommand == 'C') {
-    digitalWrite(ledUp, LOW);
-    digitalWrite(ledLeft, LOW);
-    digitalWrite(ledRight, HIGH);
-    digitalWrite(ledDown, HIGH);
-    Serial.println("Down-Right");
-  } else {
-    digitalWrite(ledUp, LOW);
-    digitalWrite(ledLeft, LOW);
-    digitalWrite(ledRight, LOW);
-    digitalWrite(ledDown, LOW);
-    Serial.println("OFF");
+  const char received = Serial.read();
+  if (received == '\r' || received == '\n' || received == currentCommand) {
+    return;
   }
 
-  delay(150);
+  currentCommand = received;
+  applyCommand(currentCommand);
 }
diff --git a/exercises/exercise-b-multi-led-pattern/exercise_b_multi_led_pattern.ino b/exercises/exercise-b-multi-led-pattern/exercise_b_multi_led_pattern.ino
index 9a692de..6e09d5c 100644
--- a/exercises/exercise-b-multi-led-pattern/exercise_b_multi_led_pattern.ino
+++ b/exercises/exercise-b-multi-led-pattern/exercise_b_multi_led_pattern.ino
@@ -1,106 +1,84 @@
-const int led1 = 2;
-const int led2 = 3;
-const int led3 = 4;
-const int led4 = 5;
+constexpr uint8_t kLedPins[] = {2, 3, 4, 5};
+constexpr uint8_t kLedCount = sizeof(kLedPins) / sizeof(kLedPins[0]);
+
+const uint8_t kBlinkAll[] = {0b1111, 0b0000};
+const uint8_t kKnightRider[] = {0b0001, 0b0010, 0b0100, 0b1000,
+                                0b0100, 0b0010};
+const uint8_t kAlternate[] = {0b0101, 0b1010};
+const uint8_t kWave[] = {0b0001, 0b0010, 0b0100, 0b1000};
+
+const uint8_t* pattern = kBlinkAll;
+uint8_t patternLength = sizeof(kBlinkAll);
+uint8_t patternIndex = 0;
+uint16_t intervalMs = 200;
+uint32_t changedAt = 0;
+char currentCommand = 'A';
+
+void writeMask(uint8_t mask) {
+  for (uint8_t index = 0; index < kLedCount; ++index) {
+    digitalWrite(kLedPins[index], bitRead(mask, index) ? HIGH : LOW);
+  }
+}
 
-char btCommand = 'A';
+void selectPattern(char command) {
+  currentCommand = command;
+  patternIndex = 0;
+  changedAt = millis();
+
+  switch (command) {
+    case 'A':
+      pattern = kBlinkAll;
+      patternLength = sizeof(kBlinkAll);
+      intervalMs = 200;
+      Serial.println(F("Pattern: BLINK ALL"));
+      break;
+    case 'B':
+      pattern = kKnightRider;
+      patternLength = sizeof(kKnightRider);
+      intervalMs = 120;
+      Serial.println(F("Pattern: KNIGHT RIDER"));
+      break;
+    case 'C':
+      pattern = kAlternate;
+      patternLength = sizeof(kAlternate);
+      intervalMs = 200;
+      Serial.println(F("Pattern: ALTERNATE"));
+      break;
+    case 'D':
+      pattern = kWave;
+      patternLength = sizeof(kWave);
+      intervalMs = 100;
+      Serial.println(F("Pattern: WAVE"));
+      break;
+    default:
+      currentCommand = 'X';
+      writeMask(0);
+      Serial.println(F("Pattern: OFF"));
+      return;
+  }
+  writeMask(pattern[patternIndex]);
+}
 
 void setup() {
   Serial.begin(9600);
-
-  pinMode(led1, OUTPUT);
-  pinMode(led2, OUTPUT);
-  pinMode(led3, OUTPUT);
-  pinMode(led4, OUTPUT);
+  for (uint8_t pin : kLedPins) {
+    pinMode(pin, OUTPUT);
+  }
+  selectPattern(currentCommand);
 }
 
 void loop() {
-  if (Serial.available() > 0) {
-    btCommand = Serial.read();
+  while (Serial.available() > 0) {
+    const char received = Serial.read();
+    if (received != '\r' && received != '\n' && received != currentCommand) {
+      selectPattern(received);
+    }
   }
 
-  if (btCommand == 'A') {
-    Serial.println("LED Pattern Name: Blink All");
-
-    digitalWrite(led1, HIGH);
-    digitalWrite(led2, HIGH);
-    digitalWrite(led3, HIGH);
-    digitalWrite(led4, HIGH);
-    delay(200);
-
-    digitalWrite(led1, LOW);
-    digitalWrite(led2, LOW);
-    digitalWrite(led3, LOW);
-    digitalWrite(led4, LOW);
-    delay(200);
-  } else if (btCommand == 'B') {
-    Serial.println("LED Pattern Name: Knight Rider");
-
-    digitalWrite(led1, HIGH);
-    digitalWrite(led2, LOW);
-    digitalWrite(led3, LOW);
-    digitalWrite(led4, LOW);
-    delay(120);
-
-    digitalWrite(led1, LOW);
-    digitalWrite(led2, HIGH);
-    delay(120);
-
-    digitalWrite(led2, LOW);
-    digitalWrite(led3, HIGH);
-    delay(120);
-
-    digitalWrite(led3, LOW);
-    digitalWrite(led4, HIGH);
-    delay(120);
-
-    digitalWrite(led4, LOW);
-    digitalWrite(led3, HIGH);
-    delay(120);
-
-    digitalWrite(led3, LOW);
-    digitalWrite(led2, HIGH);
-    delay(120);
-  } else if (btCommand == 'C') {
-    Serial.println("LED Pattern Name: Alternate Blink");
-
-    digitalWrite(led1, HIGH);
-    digitalWrite(led2, LOW);
-    digitalWrite(led3, HIGH);
-    digitalWrite(led4, LOW);
-    delay(200);
-
-    digitalWrite(led1, LOW);
-    digitalWrite(led2, HIGH);
-    digitalWrite(led3, LOW);
-    digitalWrite(led4, HIGH);
-    delay(200);
-  } else if (btCommand == 'D') {
-    Serial.println("LED Pattern Name: Wave");
-
-    digitalWrite(led1, HIGH);
-    digitalWrite(led2, LOW);
-    digitalWrite(led3, LOW);
-    digitalWrite(led4, LOW);
-    delay(100);
-
-    digitalWrite(led1, LOW);
-    digitalWrite(led2, HIGH);
-    delay(100);
-
-    digitalWrite(led2, LOW);
-    digitalWrite(led3, HIGH);
-    delay(100);
-
-    digitalWrite(led3, LOW);
-    digitalWrite(led4, HIGH);
-    delay(100);
-
-    digitalWrite(led4, LOW);
-  } else {
-    digitalWrite(led1, LOW);
-    digitalWrite(led2, LOW);
-    digitalWrite(led3, LOW);
-    digitalWrite(led4, LOW);
+  if (currentCommand != 'X' &&
+      static_cast<uint32_t>(millis() - changedAt) >= intervalMs) {
+    changedAt += intervalMs;
+    patternIndex = (patternIndex + 1) % patternLength;
+    writeMask(pattern[patternIndex]);
   }
 }
diff --git a/exercises/exercise-c-smart-fan/exercise_c_smart_fan.ino b/exercises/exercise-c-smart-fan/exercise_c_smart_fan.ino
index e1dbff3..9525adf 100644
--- a/exercises/exercise-c-smart-fan/exercise_c_smart_fan.ino
+++ b/exercises/exercise-c-smart-fan/exercise_c_smart_fan.ino
@@ -1,60 +1,65 @@
-const int pinLow = 3;
-const int pinMedium = 5;
-const int pinHigh = 6;
-const int motorPin1 = 10;
-const int motorPin2 = 11;
+// Use a rated motor driver and external motor supply. Never power a motor
+// directly from an Arduino pin.
+constexpr uint8_t kLedLow = 3;
+constexpr uint8_t kLedMedium = 5;
+constexpr uint8_t kLedHigh = 6;
+constexpr uint8_t kMotorPwm = 10;
+constexpr uint8_t kMotorDirection = 11;
 
-char switchState = 'A';
+char currentCommand = 'A';
 
-void setup() {
-  pinMode(pinLow, OUTPUT);
-  pinMode(pinMedium, OUTPUT);
-  pinMode(pinHigh, OUTPUT);
-  pinMode(motorPin1, OUTPUT);
-  pinMode(motorPin2, OUTPUT);
+void setLevel(uint8_t pwm, uint8_t ledCount, const __FlashStringHelper* name) {
+  digitalWrite(kLedLow, ledCount >= 1 ? HIGH : LOW);
+  digitalWrite(kLedMedium, ledCount >= 2 ? HIGH : LOW);
+  digitalWrite(kLedHigh, ledCount >= 3 ? HIGH : LOW);
+  digitalWrite(kMotorDirection, LOW);
+  analogWrite(kMotorPwm, pwm);
+
+  Serial.print(F("Fan: "));
+  Serial.print(name);
+  Serial.print(F(" | PWM: "));
+  Serial.println(pwm);
+}
+
+void applyCommand(char command) {
+  currentCommand = command;
+  switch (command) {
+    case 'B':
+      setLevel(120, 3, F("ON"));
+      break;
+    case 'C':
+      setLevel(170, 1, F("LOW"));
+      break;
+    case 'D':
+      setLevel(200, 2, F("MEDIUM"));
+      break;
+    case '1':
+      setLevel(255, 3, F("HIGH"));
+      break;
+    default:
+      currentCommand = 'A';
+      setLevel(0, 0, F("OFF"));
+      break;
+  }
+}
 
+void setup() {
   Serial.begin(9600);
+  pinMode(kLedLow, OUTPUT);
+  pinMode(kLedMedium, OUTPUT);
+  pinMode(kLedHigh, OUTPUT);
+  pinMode(kMotorPwm, OUTPUT);
+  pinMode(kMotorDirection, OUTPUT);
+  applyCommand(currentCommand);
 }
 
 void loop() {
-  if (Serial.available() > 0) {
-    switchState = Serial.read();
+  if (Serial.available() == 0) {
+    return;
+  }
 
-    if (switchState == 'A') {
-      digitalWrite(pinLow, LOW);
-      digitalWrite(pinMedium, LOW);
-      digitalWrite(pinHigh, LOW);
-      analogWrite(motorPin1, 0);
-      analogWrite(motorPin2, 0);
-      Serial.println("Bluetooth app character code: A | Speed Level: OFF");
-    } else if (switchState == 'B') {
-      digitalWrite(pinLow, HIGH);
-      digitalWrite(pinMedium, HIGH);
-      digitalWrite(pinHigh, HIGH);
-      analogWrite(motorPin1, 120);
-      analogWrite(motorPin2, 0);
-      Serial.println("Bluetooth app character code: B | Speed Level: ON");
-    } else if (switchState == 'C') {
-      digitalWrite(pinLow, HIGH);
-      digitalWrite(pinMedium, LOW);
-      digitalWrite(pinHigh, LOW);
-      analogWrite(motorPin1, 170);
-      analogWrite(motorPin2, 0);
-      Serial.println("Bluetooth app character code: C | Speed Level: Low");
-    } else if (switchState == 'D') {
-      digitalWrite(pinLow, HIGH);
-      digitalWrite(pinMedium, HIGH);
-      digitalWrite(pinHigh, LOW);
-      analogWrite(motorPin1, 200);
-      analogWrite(motorPin2, 0);
-      Serial.println("Bluetooth app character code: D | Speed Level: Medium");
-    } else if (switchState == '1') {
-      digitalWrite(pinLow, HIGH);
-      digitalWrite(pinMedium, HIGH);
-      digitalWrite(pinHigh, HIGH);
-      analogWrite(motorPin1, 255);
-      analogWrite(motorPin2, 0);
-      Serial.println("Bluetooth app character code: 1 | Speed Level: High");
-    }
+  const char received = Serial.read();
+  if (received != '\r' && received != '\n' && received != currentCommand) {
+    applyCommand(received);
   }
 }
diff --git a/exercises/exercise-d-wheel-simulation/exercise_d_wheel_simulation.ino b/exercises/exercise-d-wheel-simulation/exercise_d_wheel_simulation.ino
index 179ab06..9c57b70 100644
--- a/exercises/exercise-d-wheel-simulation/exercise_d_wheel_simulation.ino
+++ b/exercises/exercise-d-wheel-simulation/exercise_d_wheel_simulation.ino
@@ -1,108 +1,89 @@
-const int ledLeft = 2;
-const int ledForward = 4;
-const int ledRight = 7;
-const int ledReverse = 8;
-
-const int motorPin1B = 10;
-const int motorPin2B = 11;
-const int motorPin1A = 5;
-const int motorPin2A = 6;
-
-char switchState = 'X';
-
-void setup() {
-  Serial.begin(9600);
-
-  pinMode(ledLeft, OUTPUT);
-  pinMode(ledForward, OUTPUT);
-  pinMode(ledRight, OUTPUT);
-  pinMode(ledReverse, OUTPUT);
+// kLeftA/B and kRightA/B are logic inputs to a dual H-bridge, not direct
+// motor connections.
+constexpr uint8_t kLedLeft = 2;
+constexpr uint8_t kLedForward = 4;
+constexpr uint8_t kLedRight = 7;
+constexpr uint8_t kLedReverse = 8;
+constexpr uint8_t kLeftA = 10;
+constexpr uint8_t kLeftB = 11;
+constexpr uint8_t kRightA = 5;
+constexpr uint8_t kRightB = 6;
+
+char currentCommand = 'S';
+uint32_t blinkChangedAt = 0;
+bool reverseLedsOn = false;
+
+void setLeds(bool left, bool forward, bool right, bool reverse) {
+  digitalWrite(kLedLeft, left ? HIGH : LOW);
+  digitalWrite(kLedForward, forward ? HIGH : LOW);
+  digitalWrite(kLedRight, right ? HIGH : LOW);
+  digitalWrite(kLedReverse, reverse ? HIGH : LOW);
+}
 
-  pinMode(motorPin1B, OUTPUT);
-  pinMode(motorPin2B, OUTPUT);
-  pinMode(motorPin1A, OUTPUT);
-  pinMode(motorPin2A, OUTPUT);
+void setMotors(bool leftA, bool leftB, bool rightA, bool rightB) {
+  digitalWrite(kLeftA, leftA ? HIGH : LOW);
+  digitalWrite(kLeftB, leftB ? HIGH : LOW);
+  digitalWrite(kRightA, rightA ? HIGH : LOW);
+  digitalWrite(kRightB, rightB ? HIGH : LOW);
 }
 
-void loop() {
-  if (Serial.available() > 0) {
-    switchState = Serial.read();
-  }
+void applyCommand(char command) {
+  currentCommand = command;
+  reverseLedsOn = true;
+  blinkChangedAt = millis();
 
-  switch (switchState) {
+  switch (command) {
     case 'F':
-      Serial.println("Bluetooth app character code: F | Direction: Forward");
-
-      digitalWrite(ledLeft, LOW);
-      digitalWrite(ledForward, HIGH);
-      digitalWrite(ledRight, LOW);
-      digitalWrite(ledReverse, LOW);
-
-      digitalWrite(motorPin1B, HIGH);
-      digitalWrite(motorPin2B, LOW);
-      digitalWrite(motorPin1A, LOW);
-      digitalWrite(motorPin2A, HIGH);
+      setLeds(false, true, false, false);
+      setMotors(true, false, false, true);
+      Serial.println(F("Direction: FORWARD"));
       break;
-
     case 'L':
-      Serial.println("Bluetooth app character code: L | Direction: Left");
-
-      digitalWrite(ledLeft, HIGH);
-      digitalWrite(ledForward, LOW);
-      digitalWrite(ledRight, LOW);
-      digitalWrite(ledReverse, LOW);
-
-      digitalWrite(motorPin1B, LOW);
-      digitalWrite(motorPin2B, HIGH);
-      digitalWrite(motorPin1A, LOW);
-      digitalWrite(motorPin2A, HIGH);
+      setLeds(true, false, false, false);
+      setMotors(false, true, false, true);
+      Serial.println(F("Direction: LEFT"));
       break;
-
     case 'R':
-      Serial.println("Bluetooth app character code: R | Direction: Right");
-
-      digitalWrite(ledLeft, LOW);
-      digitalWrite(ledForward, LOW);
-      digitalWrite(ledRight, HIGH);
-      digitalWrite(ledReverse, LOW);
-
-      digitalWrite(motorPin1B, HIGH);
-      digitalWrite(motorPin2B, LOW);
-      digitalWrite(motorPin1A, HIGH);
-      digitalWrite(motorPin2A, LOW);
+      setLeds(false, false, true, false);
+      setMotors(true, false, true, false);
+      Serial.println(F("Direction: RIGHT"));
       break;
-
     case 'B':
-      Serial.println("Bluetooth app character code: B | Direction: Reverse");
-
-      digitalWrite(ledLeft, HIGH);
-      digitalWrite(ledForward, HIGH);
-      digitalWrite(ledRight, HIGH);
-      digitalWrite(ledReverse, HIGH);
-      delay(300);
-
-      digitalWrite(ledLeft, LOW);
-      digitalWrite(ledForward, LOW);
-      digitalWrite(ledRight, LOW);
-      digitalWrite(ledReverse, LOW);
-      delay(300);
-
-      digitalWrite(motorPin1B, LOW);
-      digitalWrite(motorPin2B, HIGH);
-      digitalWrite(motorPin1A, HIGH);
-      digitalWrite(motorPin2A, LOW);
+      setLeds(true, true, true, true);
+      setMotors(false, true, true, false);
+      Serial.println(F("Direction: REVERSE"));
       break;
-
     default:
-      digitalWrite(ledLeft, LOW);
-      digitalWrite(ledForward, LOW);
-      digitalWrite(ledRight, LOW);
-      digitalWrite(ledReverse, LOW);
-
-      digitalWrite(motorPin1B, LOW);
-      digitalWrite(motorPin2B, LOW);
-      digitalWrite(motorPin1A, LOW);
-      digitalWrite(motorPin2A, LOW);
+      currentCommand = 'S';
+      setLeds(false, false, false, false);
+      setMotors(false, false, false, false);
+      Serial.println(F("Direction: STOP"));
       break;
   }
 }
+
+void setup() {
+  Serial.begin(9600);
+  const uint8_t outputs[] = {kLedLeft, kLedForward, kLedRight, kLedReverse,
+                             kLeftA,   kLeftB,      kRightA,  kRightB};
+  for (uint8_t pin : outputs) {
+    pinMode(pin, OUTPUT);
+  }
+  applyCommand(currentCommand);
+}
+
+void loop() {
+  while (Serial.available() > 0) {
+    const char received = Serial.read();
+    if (received != '\r' && received != '\n' && received != currentCommand) {
+      applyCommand(received);
+    }
+  }
+
+  if (currentCommand == 'B' &&
+      static_cast<uint32_t>(millis() - blinkChangedAt) >= 300) {
+    blinkChangedAt += 300;
+    reverseLedsOn = !reverseLedsOn;
+    setLeds(reverseLedsOn, reverseLedsOn, reverseLedsOn, reverseLedsOn);
+  }
+}
diff --git a/exercises/exercise-e-knight-rider-motor-sync/exercise_e_knight_rider_motor_sync.ino b/exercises/exercise-e-knight-rider-motor-sync/exercise_e_knight_rider_motor_sync.ino
index f73195f..60c6eaf 100644
--- a/exercises/exercise-e-knight-rider-motor-sync/exercise_e_knight_rider_motor_sync.ino
+++ b/exercises/exercise-e-knight-rider-motor-sync/exercise_e_knight_rider_motor_sync.ino
@@ -1,70 +1,60 @@
-const int led1 = 3;
-const int led2 = 5;
-const int led3 = 6;
-const int led4 = 9;
-
-const int motorPin1 = 10;
-const int motorPin2 = 11;
+// Motor pins connect to a rated driver, never directly to the motor.
+constexpr uint8_t kLedPins[] = {3, 5, 6, 9};
+constexpr uint8_t kMotorPwm = 10;
+constexpr uint8_t kMotorDirection = 11;
+constexpr uint8_t kSequence[] = {0, 1, 2, 3, 2, 1};
+
+uint8_t level = 1;
+uint8_t sequenceIndex = 0;
+uint16_t intervalMs = 300;
+uint8_t motorPwm = 120;
+uint32_t changedAt = 0;
+
+void writeCurrentLed() {
+  for (uint8_t index = 0; index < 4; ++index) {
+    digitalWrite(kLedPins[index], index == kSequence[sequenceIndex] ? HIGH : LOW);
+  }
+}
 
-int btValue = 1;
-int ledDelay = 300;
-int motorSpeed1 = 120;
+void applyLevel(uint8_t newLevel) {
+  level = newLevel;
+  intervalMs = map(level, 1, 10, 300, 50);
+  motorPwm = map(level, 1, 10, 120, 255);
+  digitalWrite(kMotorDirection, LOW);
+  analogWrite(kMotorPwm, motorPwm);
+
+  Serial.print(F("Level: "));
+  Serial.print(level);
+  Serial.print(F(" | Interval ms: "));
+  Serial.print(intervalMs);
+  Serial.print(F(" | Motor PWM: "));
+  Serial.println(motorPwm);
+}
 
 void setup() {
   Serial.begin(9600);
-
-  pinMode(led1, OUTPUT);
-  pinMode(led2, OUTPUT);
-  pinMode(led3, OUTPUT);
-  pinMode(led4, OUTPUT);
-  pinMode(motorPin1, OUTPUT);
-  pinMode(motorPin2, OUTPUT);
+  for (uint8_t pin : kLedPins) {
+    pinMode(pin, OUTPUT);
+  }
+  pinMode(kMotorPwm, OUTPUT);
+  pinMode(kMotorDirection, OUTPUT);
+  applyLevel(level);
+  writeCurrentLed();
 }
 
 void loop() {
-  if (Serial.available() > 0) {
-    btValue = Serial.parseInt();
-
-    if (btValue >= 1 && btValue <= 10) {
-      ledDelay = map(btValue, 1, 10, 300, 50);
-      motorSpeed1 = map(btValue, 1, 10, 120, 255);
-
-      analogWrite(motorPin1, motorSpeed1);
-      analogWrite(motorPin2, 0);
-
-      Serial.print("Bluetooth app character code: ");
-      Serial.print(btValue);
-      Serial.print(" | LED Delay: ");
-      Serial.print(ledDelay);
-      Serial.print(" | Motor Speed: ");
-      Serial.println(motorSpeed1);
+  while (Serial.available() > 0) {
+    const char received = Serial.read();
+    if (received >= '1' && received <= '9') {
+      applyLevel(received - '0');
+    } else if (received == '0') {
+      applyLevel(10);
     }
   }
 
-  digitalWrite(led1, HIGH);
-  delay(ledDelay);
-  digitalWrite(led1, LOW);
-
-  digitalWrite(led2, HIGH);
-  delay(ledDelay);
-  digitalWrite(led2, LOW);
-
-  digitalWrite(led3, HIGH);
-  delay(ledDelay);
-  digitalWrite(led3, LOW);
-
-  digitalWrite(led4, HIGH);
-  delay(ledDelay);
-  digitalWrite(led4, LOW);
-
-  digitalWrite(led3, HIGH);
-  delay(ledDelay);
-  digitalWrite(led3, LOW);
-
-  digitalWrite(led2, HIGH);
-  delay(ledDelay);
-  digitalWrite(led2, LOW);
-
-  analogWrite(motorPin1, motorSpeed1);
-  digitalWrite(motorPin2, LOW);
+  if (static_cast<uint32_t>(millis() - changedAt) >= intervalMs) {
+    changedAt += intervalMs;
+    sequenceIndex = (sequenceIndex + 1) % sizeof(kSequence);
+    writeCurrentLed();
+  }
 }
diff --git a/exercises/exercise-f-full-system-integration/exercise_f_full_system_integration.ino b/exercises/exercise-f-full-system-integration/exercise_f_full_system_integration.ino
index e62d6a8..b21af51 100644
--- a/exercises/exercise-f-full-system-integration/exercise_f_full_system_integration.ino
+++ b/exercises/exercise-f-full-system-integration/exercise_f_full_system_integration.ino
@@ -1,143 +1,205 @@
-const int ledPinForward = 2;
-const int ledPinLeft = 4;
-const int ledPinRight = 7;
-const int ledPinBackward = 8;
-const int ledPinSpeed = 11;
-const int ledPinStatus = 13;
-
-const int motorPin1B = 3;
-const int motorPin2B = 5;
-const int motorPin1A = 6;
-const int motorPin2A = 9;
-
-const int buttonPin = 12;
-const int potPin = A0;
-
-char btCommand = 'S';
-int speedValue = 0;
+// Motor pins are logic/PWM inputs to a rated dual H-bridge. Use an external
+// motor supply and common ground; never connect motors directly to GPIO.
+constexpr uint8_t kLedForward = 2;
+constexpr uint8_t kLedLeft = 4;
+constexpr uint8_t kLedRight = 7;
+constexpr uint8_t kLedBackward = 8;
+constexpr uint8_t kLedSpeed = 11;
+constexpr uint8_t kLedStatus = 13;
+constexpr uint8_t kLeftA = 3;
+constexpr uint8_t kLeftB = 5;
+constexpr uint8_t kRightA = 6;
+constexpr uint8_t kRightB = 9;
+constexpr uint8_t kEmergencyButton = 12;
+constexpr uint8_t kSpeedPot = A0;
+constexpr uint16_t kDirectionDeadTimeMs = 50;
+
+enum class Direction : uint8_t { kStop, kForward, kBackward, kLeft, kRight };
+
+Direction requestedDirection = Direction::kStop;
+Direction activeDirection = Direction::kStop;
+uint32_t directionRequestedAt = 0;
+uint32_t emergencyBlinkAt = 0;
+uint32_t telemetryAt = 0;
+uint8_t speedPwm = 0;
+bool emergencyActive = false;
+bool emergencyLightsOn = false;
 
 void stopMotors() {
-  analogWrite(motorPin1A, 0);
-  analogWrite(motorPin2A, 0);
-  analogWrite(motorPin1B, 0);
-  analogWrite(motorPin2B, 0);
-}
-
-void setDirectionLeds(bool forwardOn, bool leftOn, bool rightOn, bool backwardOn) {
-  digitalWrite(ledPinForward, forwardOn ? HIGH : LOW);
-  digitalWrite(ledPinLeft, leftOn ? HIGH : LOW);
-  digitalWrite(ledPinRight, rightOn ? HIGH : LOW);
-  digitalWrite(ledPinBackward, backwardOn ? HIGH : LOW);
+  analogWrite(kLeftA, 0);
+  analogWrite(kLeftB, 0);
+  analogWrite(kRightA, 0);
+  analogWrite(kRightB, 0);
 }
 
-void setup() {
-  Serial.begin(9600);
-
-  pinMode(ledPinForward, OUTPUT);
-  pinMode(ledPinLeft, OUTPUT);
-  pinMode(ledPinRight, OUTPUT);
-  pinMode(ledPinBackward, OUTPUT);
-  pinMode(ledPinSpeed, OUTPUT);
-  pinMode(ledPinStatus, OUTPUT);
-
-  pinMode(motorPin1B, OUTPUT);
-  pinMode(motorPin2B, OUTPUT);
-  pinMode(motorPin1A, OUTPUT);
-  pinMode(motorPin2A, OUTPUT);
-
-  pinMode(buttonPin, INPUT_PULLUP);
+void writeDirectionLeds(Direction direction) {
+  digitalWrite(kLedForward, direction == Direction::kForward ? HIGH : LOW);
+  digitalWrite(kLedLeft, direction == Direction::kLeft ? HIGH : LOW);
+  digitalWrite(kLedRight, direction == Direction::kRight ? HIGH : LOW);
+  digitalWrite(kLedBackward, direction == Direction::kBackward ? HIGH : LOW);
 }
 
-void loop() {
-  if (Serial.available() > 0) {
-    btCommand = Serial.read();
+void requestDirection(Direction direction) {
+  if (direction == requestedDirection) {
+    return;
   }
+  stopMotors();
+  activeDirection = Direction::kStop;
+  requestedDirection = direction;
+  directionRequestedAt = millis();
+  writeDirectionLeds(direction);
+}
 
-  speedValue = map(analogRead(potPin), 0, 1023, 0, 255);
-
-  // INPUT_PULLUP means the button reads LOW when pressed.
-  if (digitalRead(buttonPin) == LOW) {
+void updateMotors() {
+  if (emergencyActive || requestedDirection == Direction::kStop) {
     stopMotors();
-
-    digitalWrite(ledPinForward, HIGH);
-    digitalWrite(ledPinLeft, HIGH);
-    digitalWrite(ledPinRight, HIGH);
-    digitalWrite(ledPinBackward, HIGH);
-    analogWrite(ledPinSpeed, 255);
-    digitalWrite(ledPinStatus, HIGH);
-    delay(300);
-
-    digitalWrite(ledPinForward, LOW);
-    digitalWrite(ledPinLeft, LOW);
-    digitalWrite(ledPinRight, LOW);
-    digitalWrite(ledPinBackward, LOW);
-    analogWrite(ledPinSpeed, 0);
-    digitalWrite(ledPinStatus, LOW);
-    delay(300);
-
-    Serial.println("Bluetooth app character code: --- | Mode: EMERGENCY | Direction: STOP | Speed: 0");
+    activeDirection = Direction::kStop;
     return;
   }
 
-  String direction = "Stop";
-
-  if (btCommand == 'F') {
-    direction = "Forward";
-
-    analogWrite(motorPin1B, 0);
-    analogWrite(motorPin2B, speedValue);
-    analogWrite(motorPin1A, speedValue);
-    analogWrite(motorPin2A, 0);
+  if (activeDirection != requestedDirection) {
+    if (static_cast<uint32_t>(millis() - directionRequestedAt) <
+        kDirectionDeadTimeMs) {
+      return;
+    }
+    activeDirection = requestedDirection;
+  }
 
-    setDirectionLeds(true, false, false, false);
-  } else if (btCommand == 'B') {
-    direction = "Backward";
+  switch (activeDirection) {
+    case Direction::kForward:
+      analogWrite(kLeftA, 0);
+      analogWrite(kLeftB, speedPwm);
+      analogWrite(kRightA, speedPwm);
+      analogWrite(kRightB, 0);
+      break;
+    case Direction::kBackward:
+      analogWrite(kLeftA, speedPwm);
+      analogWrite(kLeftB, 0);
+      analogWrite(kRightA, 0);
+      analogWrite(kRightB, speedPwm);
+      break;
+    case Direction::kLeft:
+      analogWrite(kLeftA, 0);
+      analogWrite(kLeftB, speedPwm);
+      analogWrite(kRightA, 0);
+      analogWrite(kRightB, speedPwm);
+      break;
+    case Direction::kRight:
+      analogWrite(kLeftA, speedPwm);
+      analogWrite(kLeftB, 0);
+      analogWrite(kRightA, speedPwm);
+      analogWrite(kRightB, 0);
+      break;
+    case Direction::kStop:
+      stopMotors();
+      break;
+  }
+}
 
-    analogWrite(motorPin1B, speedValue);
-    analogWrite(motorPin2B, 0);
-    analogWrite(motorPin1A, 0);
-    analogWrite(motorPin2A, speedValue);
+void handleCommand(char command) {
+  switch (command) {
+    case 'F':
+      requestDirection(Direction::kForward);
+      break;
+    case 'B':
+      requestDirection(Direction::kBackward);
+      break;
+    case 'L':
+      requestDirection(Direction::kLeft);
+      break;
+    case 'R':
+      requestDirection(Direction::kRight);
+      break;
+    default:
+      requestDirection(Direction::kStop);
+      break;
+  }
+}
 
-    setDirectionLeds(false, false, false, true);
-  } else if (btCommand == 'L') {
-    direction = "Left";
+const __FlashStringHelper* directionName(Direction direction) {
+  switch (direction) {
+    case Direction::kForward:
+      return F("FORWARD");
+    case Direction::kBackward:
+      return F("BACKWARD");
+    case Direction::kLeft:
+      return F("LEFT");
+    case Direction::kRight:
+      return F("RIGHT");
+    default:
+      return F("STOP");
+  }
+}
 
-    analogWrite(motorPin1B, 0);
-    analogWrite(motorPin2B, speedValue);
-    analogWrite(motorPin1A, 0);
-    analogWrite(motorPin2A, speedValue);
+void updateEmergencyStop() {
+  const bool pressed = digitalRead(kEmergencyButton) == LOW;
+  if (pressed && !emergencyActive) {
+    emergencyActive = true;
+    requestDirection(Direction::kStop);
+    stopMotors();
+    emergencyBlinkAt = millis();
+    emergencyLightsOn = true;
+    Serial.println(F("Mode: EMERGENCY | Direction: STOP | Send a new command after release"));
+  } else if (!pressed && emergencyActive) {
+    emergencyActive = false;
+    emergencyLightsOn = false;
+    writeDirectionLeds(Direction::kStop);
+    Serial.println(F("Mode: READY | Direction remains STOP"));
+  }
 
-    setDirectionLeds(false, true, false, false);
-  } else if (btCommand == 'R') {
-    direction = "Right";
+  if (emergencyActive &&
+      static_cast<uint32_t>(millis() - emergencyBlinkAt) >= 200) {
+    emergencyBlinkAt += 200;
+    emergencyLightsOn = !emergencyLightsOn;
+  }
 
-    analogWrite(motorPin1B, speedValue);
-    analogWrite(motorPin2B, 0);
-    analogWrite(motorPin1A, speedValue);
-    analogWrite(motorPin2A, 0);
+  if (emergencyActive) {
+    digitalWrite(kLedForward, emergencyLightsOn ? HIGH : LOW);
+    digitalWrite(kLedLeft, emergencyLightsOn ? HIGH : LOW);
+    digitalWrite(kLedRight, emergencyLightsOn ? HIGH : LOW);
+    digitalWrite(kLedBackward, emergencyLightsOn ? HIGH : LOW);
+  }
+}
 
-    setDirectionLeds(false, false, true, false);
-  } else {
-    stopMotors();
-    setDirectionLeds(false, false, false, false);
+void printTelemetry() {
+  if (static_cast<uint32_t>(millis() - telemetryAt) < 500) {
+    return;
   }
+  telemetryAt += 500;
+  Serial.print(F("Mode: "));
+  Serial.print(emergencyActive ? F("EMERGENCY") : F("NORMAL"));
+  Serial.print(F(" | Direction: "));
+  Serial.print(directionName(requestedDirection));
+  Serial.print(F(" | PWM: "));
+  Serial.println(emergencyActive ? 0 : speedPwm);
+}
 
-  if (speedValue < 85) {
-    analogWrite(ledPinSpeed, 0);
-  } else if (speedValue < 170) {
-    analogWrite(ledPinSpeed, 128);
-  } else {
-    analogWrite(ledPinSpeed, 255);
+void setup() {
+  Serial.begin(9600);
+  const uint8_t outputs[] = {kLedForward, kLedLeft, kLedRight, kLedBackward,
+                             kLedSpeed,   kLedStatus, kLeftA,    kLeftB,
+                             kRightA,     kRightB};
+  for (uint8_t pin : outputs) {
+    pinMode(pin, OUTPUT);
   }
+  pinMode(kEmergencyButton, INPUT_PULLUP);
+  stopMotors();
+  writeDirectionLeds(Direction::kStop);
+}
 
-  digitalWrite(ledPinStatus, HIGH);
+void loop() {
+  updateEmergencyStop();
 
-  Serial.print("Bluetooth app character code: ");
-  Serial.print(btCommand);
-  Serial.print(" | Mode: Normal | Direction: ");
-  Serial.print(direction);
-  Serial.print(" | Speed: ");
-  Serial.println(speedValue);
+  while (!emergencyActive && Serial.available() > 0) {
+    const char received = Serial.read();
+    if (received != '\r' && received != '\n') {
+      handleCommand(received);
+    }
+  }
 
-  delay(100);
+  speedPwm = map(analogRead(kSpeedPot), 0, 1023, 0, 255);
+  analogWrite(kLedSpeed, emergencyActive ? 0 : speedPwm);
+  digitalWrite(kLedStatus, emergencyActive ? LOW : HIGH);
+  updateMotors();
+  printTelemetry();
 }
diff --git a/extras/basic-bluetooth-led/basic_bluetooth_led.ino b/extras/basic-bluetooth-led/basic_bluetooth_led.ino
index 50e88af..2142667 100644
--- a/extras/basic-bluetooth-led/basic_bluetooth_led.ino
+++ b/extras/basic-bluetooth-led/basic_bluetooth_led.ino
@@ -1,22 +1,27 @@
-const int ledPin = 5;
-
-char switchState = '0';
+constexpr uint8_t kLedPin = 5;
+bool ledOn = false;
 
 void setup() {
   Serial.begin(9600);
-  pinMode(ledPin, OUTPUT);
+  pinMode(kLedPin, OUTPUT);
+  digitalWrite(kLedPin, LOW);
+  Serial.println(F("Send 1 for ON or 0 for OFF."));
 }
 
 void loop() {
-  while (Serial.available() > 0) {
-    switchState = Serial.read();
-    Serial.println(switchState);
-    delay(100);
+  if (Serial.available() == 0) {
+    return;
+  }
 
-    if (switchState == '1') {
-      digitalWrite(ledPin, HIGH);
-    } else if (switchState == '0') {
-      digitalWrite(ledPin, LOW);
-    }
+  const char received = Serial.read();
+  if (received == '1') {
+    ledOn = true;
+  } else if (received == '0') {
+    ledOn = false;
+  } else {
+    return;
   }
+
+  digitalWrite(kLedPin, ledOn ? HIGH : LOW);
+  Serial.println(ledOn ? F("LED: ON") : F("LED: OFF"));
 }

From c5133012e6a573cc5d8e97ee634c6af498f79ea4 Mon Sep 17 00:00:00 2001
From: "@dev.mako" <prinz.jewel11@gmail.com>
Date: Wed, 29 Jul 2026 10:14:50 +0800
Subject: [PATCH 2/4] docs: turn sketches into a safety-first learning path

---
 CHANGELOG.md               |  10 +++
 CODE_OF_CONDUCT.md         |  13 ++++
 CONTRIBUTING.md            |  30 ++++++++
 LICENSE                    |  21 ++++++
 README.md                  | 151 +++++++++++++------------------------
 SECURITY.md                |   8 ++
 VERSION                    |   1 +
 docs/getting-started.md    |  41 ++++++++++
 docs/hardware-safety.md    |  38 ++++++++++
 docs/lessons/exercise-a.md |  35 +++++++++
 docs/lessons/exercise-b.md |  32 ++++++++
 docs/lessons/exercise-c.md |  35 +++++++++
 docs/lessons/exercise-d.md |  33 ++++++++
 docs/lessons/exercise-e.md |  31 ++++++++
 docs/lessons/exercise-f.md |  41 ++++++++++
 docs/serial-control.md     |  29 +++++++
 docs/troubleshooting.md    |  35 +++++++++
 17 files changed, 486 insertions(+), 98 deletions(-)
 create mode 100644 CHANGELOG.md
 create mode 100644 CODE_OF_CONDUCT.md
 create mode 100644 CONTRIBUTING.md
 create mode 100644 LICENSE
 create mode 100644 SECURITY.md
 create mode 100644 VERSION
 create mode 100644 docs/getting-started.md
 create mode 100644 docs/hardware-safety.md
 create mode 100644 docs/lessons/exercise-a.md
 create mode 100644 docs/lessons/exercise-b.md
 create mode 100644 docs/lessons/exercise-c.md
 create mode 100644 docs/lessons/exercise-d.md
 create mode 100644 docs/lessons/exercise-e.md
 create mode 100644 docs/lessons/exercise-f.md
 create mode 100644 docs/serial-control.md
 create mode 100644 docs/troubleshooting.md

diff --git a/CHANGELOG.md b/CHANGELOG.md
new file mode 100644
index 0000000..1fdf8e2
--- /dev/null
+++ b/CHANGELOG.md
@@ -0,0 +1,10 @@
+# Changelog
+
+## [1.0.0] - 2026-07-29
+
+- Turn the sketch collection into a six-lesson learning path.
+- Add wiring, safety, serial-control, troubleshooting, and lesson documentation.
+- Refactor every sketch to remain responsive without blocking pattern delays.
+- Add official Arduino Uno compilation checks and contributor templates.
+
+[1.0.0]: https://github.com/devkyato/Arduino-Programs-Guide/releases/tag/v1.0.0
diff --git a/CODE_OF_CONDUCT.md b/CODE_OF_CONDUCT.md
new file mode 100644
index 0000000..ed15846
--- /dev/null
+++ b/CODE_OF_CONDUCT.md
@@ -0,0 +1,13 @@
+# Code of Conduct
+
+This project is a learning space. Be patient, specific, and constructive. Welcome
+beginner questions, explain corrections without ridicule, and respect different
+backgrounds and experience levels.
+
+Harassment, discriminatory language, personal attacks, and publishing private
+information are not acceptable. Report problems privately through the
+maintainer's GitHub profile. Maintainers may remove content or restrict
+participation to protect the community.
+
+This policy is adapted from the
+[Contributor Covenant 2.1](https://www.contributor-covenant.org/version/2/1/code_of_conduct/).
diff --git a/CONTRIBUTING.md b/CONTRIBUTING.md
new file mode 100644
index 0000000..bcde258
--- /dev/null
+++ b/CONTRIBUTING.md
@@ -0,0 +1,30 @@
+# Contributing
+
+## Choose a contribution
+
+Look for issues labeled `good first issue`, `documentation`, or `hardware`. If a
+change alters a pin map, command, or learning objective, open an issue first.
+
+## Verify your work
+
+- Compile every changed sketch for Arduino Uno.
+- Test hardware changes with the exact circuit described in the pull request.
+- Keep `loop()` responsive; do not add long `delay()` calls.
+- Update the matching lesson when behavior or wiring changes.
+- Never recommend powering a motor directly from GPIO or the USB 5 V rail.
+
+Install Arduino CLI and run:
+
+```sh
+arduino-cli core update-index
+arduino-cli core install arduino:avr
+arduino-cli compile --fqbn arduino:avr:uno exercises/exercise-a-arrow-controller
+```
+
+CI recursively compiles all exercise and extra sketches.
+
+## Pull requests
+
+Keep the change focused, explain what a student learns from it, and list the
+board, core version, power source, and driver used for any hardware test.
+Participation is governed by the [Code of Conduct](CODE_OF_CONDUCT.md).
diff --git a/LICENSE b/LICENSE
new file mode 100644
index 0000000..f24b1a7
--- /dev/null
+++ b/LICENSE
@@ -0,0 +1,21 @@
+MIT License
+
+Copyright (c) 2026 devkyato
+
+Permission is hereby granted, free of charge, to any person obtaining a copy
+of this software and associated documentation files (the "Software"), to deal
+in the Software without restriction, including without limitation the rights
+to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+copies of the Software, and to permit persons to whom the Software is
+furnished to do so, subject to the following conditions:
+
+The above copyright notice and this permission notice shall be included in all
+copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+SOFTWARE.
diff --git a/README.md b/README.md
index 99cf46f..76b92c9 100644
--- a/README.md
+++ b/README.md
@@ -1,115 +1,70 @@
-# Supplementaries Arduino Exercises
+# Arduino Programs Guide
 
-This repository contains cleaned, formatted, and organized Arduino sketches for Exercises A to F, plus one extra Bluetooth LED example.
+[![Sketch compilation](https://github.com/devkyato/Arduino-Programs-Guide/actions/workflows/compile.yml/badge.svg)](https://github.com/devkyato/Arduino-Programs-Guide/actions/workflows/compile.yml)
+[![License: MIT](https://img.shields.io/badge/license-MIT-blue.svg)](LICENSE)
 
-## Repository Contents
+A progressive, hands-on Arduino Uno course covering serial commands, LED patterns,
+PWM motor control, state machines, and emergency-stop behavior. Each lesson
+includes a compile-checked sketch, wiring contract, test procedure, and extension
+ideas.
 
-- `exercises/exercise-a-arrow-controller/exercise_a_arrow_controller.ino`
-- `exercises/exercise-b-multi-led-pattern/exercise_b_multi_led_pattern.ino`
-- `exercises/exercise-c-smart-fan/exercise_c_smart_fan.ino`
-- `exercises/exercise-d-wheel-simulation/exercise_d_wheel_simulation.ino`
-- `exercises/exercise-e-knight-rider-motor-sync/exercise_e_knight_rider_motor_sync.ino`
-- `exercises/exercise-f-full-system-integration/exercise_f_full_system_integration.ino`
-- `extras/basic-bluetooth-led/basic_bluetooth_led.ino`
+> [!CAUTION]
+> Never connect a DC motor directly to an Arduino pin. Motor lessons require a
+> suitable transistor or H-bridge driver, flyback protection, an external motor
+> supply, and a shared ground. Read [Hardware safety](docs/hardware-safety.md)
+> before Exercises C–F.
 
-Everything listed above is already included in the repository.
+## Learning path
 
-## How To Use
+| Lesson | Project | Main concepts | Hardware |
+| --- | --- | --- | --- |
+| [A](docs/lessons/exercise-a.md) | Arrow controller | serial input, functions, digital output | 4 LEDs |
+| [B](docs/lessons/exercise-b.md) | Pattern selector | arrays, bit masks, non-blocking timing | 4 LEDs |
+| [C](docs/lessons/exercise-c.md) | Smart fan | PWM, command mapping, safe motor stop | 3 LEDs, driver, motor |
+| [D](docs/lessons/exercise-d.md) | Wheel simulation | H-bridge direction, state machines | 4 LEDs, dual driver, 2 motors |
+| [E](docs/lessons/exercise-e.md) | Synchronized scanner | numeric parsing, `map()`, animation | 4 LEDs, driver, motor |
+| [F](docs/lessons/exercise-f.md) | Integrated vehicle | analog input, emergency override, telemetry | full circuit |
 
-1. Clone or download this repository.
-2. Open the Arduino IDE.
-3. Open the exercise folder you want to test.
-4. Load the `.ino` file for that exercise.
-5. Connect your Arduino board.
-6. Select the correct board and COM port in the Arduino IDE.
-7. Upload the sketch.
-8. Open the Serial Monitor and set the baud rate to `9600`.
-9. Send commands from your Bluetooth app or serial connection based on the exercise instructions below.
+There is also a small [Bluetooth LED warm-up](extras/basic-bluetooth-led/)
+for testing a serial module before starting the main exercises.
 
-## Exercise Summary
+## Start here
 
-### Exercise A
+1. Read [Getting started](docs/getting-started.md).
+2. Build Exercise A with the board disconnected from power.
+3. Upload the sketch and test it in Serial Monitor before adding Bluetooth.
+4. Complete the lesson's verification checklist.
+5. Commit your observations and improvements in your own fork.
 
-Arrow controller using 4 LEDs.
+All sketches use `9600` baud and accept the same characters from USB Serial or a
+TTL serial Bluetooth module. On an Uno, the hardware serial pins are shared with
+USB; disconnect the module from pins 0/1 while uploading. See
+[Serial control](docs/serial-control.md).
 
-- `Q` = Up-Left
-- `E` = Up-Right
-- `Z` = Down-Left
-- `C` = Down-Right
-- `X` = OFF
+## Repository layout
 
-The Serial Monitor prints only the direction name.
+```text
+exercises/        Six progressively more involved Arduino sketches
+extras/           Small setup and diagnostic sketches
+docs/lessons/     Objectives, wiring tables, tests, and challenges
+docs/             Setup, safety, serial, and troubleshooting guides
+.github/          Contribution templates and automated compile checks
+```
 
-### Exercise B
+## Supported environment
 
-Bluetooth-controlled multi-LED pattern selector.
+The examples target the Arduino Uno and the Arduino AVR Boards core. CI compiles
+every sketch with the official Arduino toolchain. Other boards may use different
+PWM pins, voltage levels, serial ports, or ADC ranges; porting notes are welcome
+only when verified on hardware.
 
-- `A` = Blink All
-- `B` = Knight Rider
-- `C` = Alternate Blink
-- `D` = Wave
+## Contributing
 
-The Serial Monitor prints the selected LED pattern name.
+Student contributions are encouraged. Good changes include clearer diagrams,
+hardware results, non-blocking improvements, and new tests that preserve each
+lesson's learning objective. Read [CONTRIBUTING.md](CONTRIBUTING.md) before
+opening a pull request.
 
-### Exercise C
+## License
 
-Smart fan control using Bluetooth, 3 LEDs, and a DC motor.
-
-- `A` = OFF
-- `B` = ON
-- `C` = LOW
-- `D` = MEDIUM
-- `1` = HIGH
-
-The LEDs show the speed level, and the motor speed changes with the selected mode.
-
-### Exercise D
-
-Wheel of a car simulation using Bluetooth.
-
-- `F` = Forward
-- `L` = Left
-- `R` = Right
-- `B` = Reverse
-
-The LEDs show direction, and the wheels or motor outputs move according to the command.
-
-### Exercise E
-
-Knight Rider LED pattern with motor speed sync.
-
-- Send a Bluetooth value from `1` to `10`
-
-The LED animation becomes faster as the value increases, and the motor speed also increases.
-
-### Exercise F
-
-Full system integration with direction control, speed control, and emergency override.
-
-- `F` = Forward
-- `L` = Left
-- `R` = Right
-- `B` = Backward
-- Potentiometer = Speed control
-- Tact switch = Emergency stop override
-
-The system status and speed indicator LEDs are also used in this sketch.
-
-## Notes
-
-- The sketches were reformatted for readability and split into separate files.
-- Exercise A and Exercise B were created from the assignment screenshots.
-- Exercise E was adjusted so values `1` to `10` work more reliably.
-- Exercise F was adjusted so the emergency stop works correctly with `INPUT_PULLUP`.
-- Exercise F pin assignments were cleaned up for a more practical Arduino setup.
-
-## Important Reminder
-
-You may still need to change some pin numbers depending on:
-
-- your Arduino board
-- your motor driver
-- your Bluetooth module wiring
-- your actual LED and button connections
-
-If your Bluetooth app uses different button letters, you can edit the command characters in each sketch.
+[MIT](LICENSE)
diff --git a/SECURITY.md b/SECURITY.md
new file mode 100644
index 0000000..af0c0fe
--- /dev/null
+++ b/SECURITY.md
@@ -0,0 +1,8 @@
+# Security and safety reports
+
+Use GitHub private vulnerability reporting for software vulnerabilities. For an
+electrical safety concern, stop using the circuit and open an issue without
+energizing it again. Do not include personal information.
+
+Include the lesson, board, driver, supply voltage/current rating, wiring, and
+observed behavior. The latest release is the supported version.
diff --git a/VERSION b/VERSION
new file mode 100644
index 0000000..3eefcb9
--- /dev/null
+++ b/VERSION
@@ -0,0 +1 @@
+1.0.0
diff --git a/docs/getting-started.md b/docs/getting-started.md
new file mode 100644
index 0000000..4f91ccc
--- /dev/null
+++ b/docs/getting-started.md
@@ -0,0 +1,41 @@
+# Getting started
+
+## What you need
+
+- Arduino Uno or compatible 5 V AVR board
+- data-capable USB cable
+- breadboard and jumper wires
+- 220–330 Ω resistor for each LED
+- components listed in the selected lesson
+- Arduino IDE 2 or Arduino CLI
+
+Exercises C–F also require an appropriate motor driver, protected motor supply,
+and a multimeter. Do not begin those exercises until you understand the
+[hardware safety rules](hardware-safety.md).
+
+## First upload
+
+1. Install Arduino IDE from the official Arduino website.
+2. Connect the Uno and select **Tools > Board > Arduino Uno**.
+3. Select the board's port.
+4. Open the `.ino` file inside its matching folder.
+5. Click **Verify**, then **Upload**.
+6. Open Serial Monitor, choose `9600 baud`, and use **No line ending**.
+
+Test the USB serial command path before connecting a Bluetooth module. This keeps
+software, wiring, and wireless troubleshooting separate.
+
+## Breadboard habits
+
+- Disconnect USB and external power before changing wiring.
+- Check LED polarity and always use a series resistor.
+- Use one ground reference across the Arduino, driver, and external supply.
+- Keep a written pin map beside the circuit.
+- Measure the supply before connecting the board.
+- Upload a motor-stop sketch before attaching motor power.
+
+## Evidence for each lesson
+
+Record the board/core version, a wiring photo or diagram, commands tested,
+observed serial output, and any changes made. A successful compile is not proof
+that a physical circuit is safe or correct.
diff --git a/docs/hardware-safety.md b/docs/hardware-safety.md
new file mode 100644
index 0000000..dce9c9c
--- /dev/null
+++ b/docs/hardware-safety.md
@@ -0,0 +1,38 @@
+# Hardware safety
+
+## LEDs
+
+Use one 220–330 Ω series resistor per LED. Confirm polarity before power-up.
+The pin maps describe logic connections, not permission to exceed the board's
+electrical ratings.
+
+## DC motors
+
+An Arduino GPIO pin is a logic signal, not a motor power source. Motors create
+startup current and inductive voltage spikes that can damage the microcontroller.
+Exercises C–F assume:
+
+- a transistor/MOSFET driver or H-bridge rated above the motor's stall current;
+- flyback protection, built into the driver or added as required;
+- a separately rated motor supply;
+- a common ground between Arduino, driver, and motor supply;
+- no motor current flowing through an Arduino GPIO pin.
+
+For bidirectional exercises, use an H-bridge or dual motor-driver module. Verify
+its truth table because input polarity differs between modules.
+
+## Power-up checklist
+
+1. Disconnect the motor supply.
+2. Check continuity and polarity.
+3. Confirm driver input and enable voltage compatibility.
+4. Upload the sketch.
+5. Verify stop-state output with LEDs or a multimeter.
+6. Secure the motor so moving parts cannot cause injury.
+7. Connect motor power and begin at the lowest PWM command.
+
+If the Arduino resets, the driver heats rapidly, or wiring smells hot, disconnect
+power immediately. Do not solve power problems by bypassing protection.
+
+Official background: [Arduino transistor motor control](https://docs.arduino.cc/learn/electronics/transistor-motor-control)
+and [Arduino Motor Shield Rev3](https://docs.arduino.cc/hardware/motor-shield-rev3).
diff --git a/docs/lessons/exercise-a.md b/docs/lessons/exercise-a.md
new file mode 100644
index 0000000..7fb4c7c
--- /dev/null
+++ b/docs/lessons/exercise-a.md
@@ -0,0 +1,35 @@
+# Exercise A: arrow controller
+
+## Objective
+
+Translate one-character serial commands into four LED outputs. This introduces
+`Serial.available()`, `Serial.read()`, functions, and a safe default state.
+
+## Wiring
+
+Connect each pin through its own 220–330 Ω resistor to an LED anode; connect each
+LED cathode to ground.
+
+| Meaning | Uno pin |
+| --- | --- |
+| Up | 2 |
+| Left | 3 |
+| Right | 4 |
+| Down | 5 |
+
+## Commands
+
+`Q` = up-left, `E` = up-right, `Z` = down-left, `C` = down-right, and `X` (or
+any unknown character) = off.
+
+## Verify
+
+1. Send every documented command once.
+2. Confirm the two expected LEDs and serial message.
+3. Send an unknown character and confirm all LEDs turn off.
+4. Leave the sketch idle and confirm it does not repeatedly print.
+
+## Challenge
+
+Add `W`, `A`, `S`, and `D` for single-direction output without duplicating the
+pin-writing logic.
diff --git a/docs/lessons/exercise-b.md b/docs/lessons/exercise-b.md
new file mode 100644
index 0000000..74ac6c7
--- /dev/null
+++ b/docs/lessons/exercise-b.md
@@ -0,0 +1,32 @@
+# Exercise B: multi-LED patterns
+
+## Objective
+
+Use arrays and bit masks to animate four LEDs while continuing to read serial
+input. The sketch replaces long sequences of `delay()` calls with elapsed-time
+checks.
+
+## Wiring
+
+Pins 2, 3, 4, and 5 each drive one LED through a 220–330 Ω resistor.
+
+## Commands
+
+| Command | Pattern |
+| --- | --- |
+| `A` | all LEDs blink |
+| `B` | scanner / Knight Rider |
+| `C` | alternating pairs |
+| `D` | one-way wave |
+| other | off |
+
+## Verify
+
+Start each pattern, then switch commands mid-animation. The new pattern should
+start immediately. Leave it running across the `millis()` rollover only for an
+extended validation; unsigned elapsed-time arithmetic keeps it safe.
+
+## Challenge
+
+Add a pattern by defining a mask array and selecting it in `selectPattern()`.
+Avoid adding new `digitalWrite()` sequences or blocking delays.
diff --git a/docs/lessons/exercise-c.md b/docs/lessons/exercise-c.md
new file mode 100644
index 0000000..92398ce
--- /dev/null
+++ b/docs/lessons/exercise-c.md
@@ -0,0 +1,35 @@
+# Exercise C: smart fan
+
+## Objective
+
+Map serial commands to PWM levels and LED indicators while maintaining a
+fail-safe off command.
+
+Read [Hardware safety](../hardware-safety.md) before wiring a motor.
+
+## Driver interface
+
+| Signal | Uno pin |
+| --- | --- |
+| Low / medium / high LEDs | 3 / 5 / 6 |
+| Driver PWM or enable | 10 |
+| Driver direction input | 11 |
+
+The exact motor, supply, driver outputs, and flyback protection depend on the
+driver datasheet. Pins 10 and 11 connect only to logic inputs.
+
+## Commands
+
+`A` = off, `B` = on at PWM 120, `C` = low at 170, `D` = medium at 200, and
+`1` = high at 255. Unknown input also stops the motor.
+
+## Verify
+
+Test first with the motor supply disconnected and measure the PWM/logic response.
+Then secure the motor, connect its rated supply, and start with `A`. Record driver
+temperature and supply behavior; stop immediately if either is abnormal.
+
+## Challenge
+
+Replace the fixed levels with a table containing command, PWM, LED mask, and
+label, while preserving the off-on-unknown behavior.
diff --git a/docs/lessons/exercise-d.md b/docs/lessons/exercise-d.md
new file mode 100644
index 0000000..24e7ffb
--- /dev/null
+++ b/docs/lessons/exercise-d.md
@@ -0,0 +1,33 @@
+# Exercise D: wheel simulation
+
+## Objective
+
+Control two H-bridge channels as a small differential-drive system and run a
+reverse warning animation without blocking serial commands.
+
+## Pin map
+
+| Signal | Uno pin |
+| --- | --- |
+| Left / forward / right / reverse LEDs | 2 / 4 / 7 / 8 |
+| Left driver inputs A / B | 10 / 11 |
+| Right driver inputs A / B | 5 / 6 |
+
+Confirm the H-bridge truth table before connecting motors. Reversing polarity or
+using a different driver may require changing the four logic values.
+
+## Commands
+
+`F` = forward, `L` = left, `R` = right, `B` = reverse, and any other character
+= stop.
+
+## Verify
+
+With motor power disconnected, check each driver input and direction LED. With
+the vehicle lifted so wheels are clear, connect motor power at low voltage and
+verify one direction at a time. Confirm a stop command is accepted while the
+reverse LEDs are blinking.
+
+## Challenge
+
+Add PWM enable pins and three speed levels without changing direction input pins.
diff --git a/docs/lessons/exercise-e.md b/docs/lessons/exercise-e.md
new file mode 100644
index 0000000..5f58453
--- /dev/null
+++ b/docs/lessons/exercise-e.md
@@ -0,0 +1,31 @@
+# Exercise E: synchronized scanner
+
+## Objective
+
+Map a numeric level to both animation interval and motor PWM, demonstrating
+bounded input, arrays, and synchronized outputs.
+
+## Pin map
+
+| Signal | Uno pin |
+| --- | --- |
+| Four LEDs | 3, 5, 6, 9 |
+| Driver PWM / direction | 10 / 11 |
+
+Motor pins connect only to a rated driver. Follow
+[Hardware safety](../hardware-safety.md).
+
+## Commands
+
+Send `1`–`9` for those levels and `0` for level 10. Level 1 uses a 300 ms step
+and PWM 120; level 10 uses a 50 ms step and PWM 255.
+
+## Verify
+
+Confirm every input produces values within those bounds. Change level while the
+scanner is moving and verify serial input remains responsive.
+
+## Challenge
+
+Add an `S` command that stops the motor and LEDs, then resumes the previous level
+when a numeric command arrives.
diff --git a/docs/lessons/exercise-f.md b/docs/lessons/exercise-f.md
new file mode 100644
index 0000000..1ca78cf
--- /dev/null
+++ b/docs/lessons/exercise-f.md
@@ -0,0 +1,41 @@
+# Exercise F: integrated vehicle
+
+## Objective
+
+Combine differential drive, potentiometer speed input, direction indicators,
+periodic telemetry, and an emergency-stop override in one responsive loop.
+
+## Pin map
+
+| Signal | Uno pin |
+| --- | --- |
+| Forward / left / right / backward LEDs | 2 / 4 / 7 / 8 |
+| Speed / status LEDs | 11 / 13 |
+| Left driver A / B | 3 / 5 |
+| Right driver A / B | 6 / 9 |
+| Emergency button | 12 to GND (`INPUT_PULLUP`) |
+| Speed potentiometer wiper | A0 |
+
+The potentiometer's outer legs connect to 5 V and GND. Motor connections require
+a rated dual H-bridge, external supply, protection, and common ground.
+
+## Behavior
+
+`F`, `B`, `L`, and `R` request motion; any other command requests stop. A 50 ms
+stop interval occurs before a new direction is energized. Pressing the emergency
+button stops all motor PWM immediately, flashes the direction LEDs, and discards
+the old direction. Releasing the button does not resume motion—a new command is
+required.
+
+## Verify
+
+1. Keep motor power disconnected and verify every indicator and driver input.
+2. Press emergency stop during every requested direction.
+3. Hold the button, send commands, then release it; the motors must remain stopped.
+4. Turn the potentiometer through its range and check reported PWM.
+5. Secure the vehicle before cautious powered testing.
+
+## Challenge
+
+Debounce the release transition without delaying emergency activation, then
+explain why stopping should not wait for debounce.
diff --git a/docs/serial-control.md b/docs/serial-control.md
new file mode 100644
index 0000000..bf6b0ec
--- /dev/null
+++ b/docs/serial-control.md
@@ -0,0 +1,29 @@
+# Serial and Bluetooth control
+
+All sketches use `Serial` at 9600 baud. Commands can come from Arduino IDE Serial
+Monitor or from a TTL serial Bluetooth module that presents the same byte stream.
+
+## Uno wiring
+
+| Module | Arduino Uno |
+| --- | --- |
+| TX | RX / pin 0 |
+| RX | TX / pin 1 through level shifting when required |
+| GND | GND |
+| VCC | Module-specific rated supply |
+
+Check the module's datasheet: many receive pins are 3.3 V logic even when the
+breakout board accepts 5 V power. Disconnect pins 0 and 1 during upload because
+the Uno USB interface shares this hardware serial port.
+
+## Reliable test sequence
+
+1. Test commands over USB with no wireless module connected.
+2. Configure Serial Monitor to **No line ending**.
+3. Connect the unpowered module and verify voltage levels.
+4. Pair the module and send the same characters.
+5. If commands fail, echo bytes with the basic Bluetooth LED sketch.
+
+The sketches ignore carriage-return and newline bytes, so other line-ending
+settings should not cause an unsafe command. Unknown commands select a stopped or
+off state in motor exercises.
diff --git a/docs/troubleshooting.md b/docs/troubleshooting.md
new file mode 100644
index 0000000..447f54a
--- /dev/null
+++ b/docs/troubleshooting.md
@@ -0,0 +1,35 @@
+# Troubleshooting
+
+## Upload fails
+
+- Disconnect anything from Uno pins 0 and 1.
+- Confirm the board and port.
+- Try a known data-capable USB cable.
+- Close other serial-monitor applications.
+
+## LEDs behave backwards
+
+Check LED polarity, resistor placement, and the lesson pin table. Do not remove a
+resistor to make an LED brighter.
+
+## Commands include unexpected values
+
+Select **No line ending** in Serial Monitor. The maintained sketches ignore CR/LF,
+but a custom sketch may not.
+
+## Motor does not move
+
+Disconnect power first. Check the external supply, shared ground, driver enable
+pin, driver truth table, and motor stall-current rating. Measure driver output
+without holding the motor shaft.
+
+## Arduino resets when the motor starts
+
+This usually indicates supply noise, excessive current, missing protection, or
+poor grounding—not a reason to draw motor power from GPIO. Recheck the complete
+driver and power design.
+
+## Sketch compiles but hardware fails
+
+Compilation only verifies source compatibility. Compare the actual circuit to the
+lesson pin map, then reduce the system to one LED or one unloaded driver channel.

From 17b6a441e2d4da28f1f0a43e1ef9a69178e46bc5 Mon Sep 17 00:00:00 2001
From: "@dev.mako" <prinz.jewel11@gmail.com>
Date: Wed, 29 Jul 2026 10:14:50 +0800
Subject: [PATCH 3/4] ci: compile every Uno sketch and package releases

---
 .github/ISSUE_TEMPLATE/bug.yml    | 32 ++++++++++++++++++
 .github/ISSUE_TEMPLATE/config.yml |  5 +++
 .github/ISSUE_TEMPLATE/lesson.yml | 23 +++++++++++++
 .github/PULL_REQUEST_TEMPLATE.md  | 14 ++++++++
 .github/dependabot.yml            |  9 +++++
 .github/workflows/compile.yml     | 37 ++++++++++++++++++++
 .github/workflows/release.yml     | 25 ++++++++++++++
 .gitignore                        |  7 ++++
 tools/build_release.py            | 56 +++++++++++++++++++++++++++++++
 9 files changed, 208 insertions(+)
 create mode 100644 .github/ISSUE_TEMPLATE/bug.yml
 create mode 100644 .github/ISSUE_TEMPLATE/config.yml
 create mode 100644 .github/ISSUE_TEMPLATE/lesson.yml
 create mode 100644 .github/PULL_REQUEST_TEMPLATE.md
 create mode 100644 .github/dependabot.yml
 create mode 100644 .github/workflows/compile.yml
 create mode 100644 .github/workflows/release.yml
 create mode 100644 .gitignore
 create mode 100644 tools/build_release.py

diff --git a/.github/ISSUE_TEMPLATE/bug.yml b/.github/ISSUE_TEMPLATE/bug.yml
new file mode 100644
index 0000000..79b8756
--- /dev/null
+++ b/.github/ISSUE_TEMPLATE/bug.yml
@@ -0,0 +1,32 @@
+name: Sketch bug
+description: Report a reproducible sketch or documentation error.
+title: "[Bug]: "
+labels: ["bug"]
+body:
+  - type: input
+    id: lesson
+    attributes:
+      label: Lesson and sketch
+      placeholder: Exercise B / exercise_b_multi_led_pattern.ino
+    validations:
+      required: true
+  - type: input
+    id: environment
+    attributes:
+      label: Board and core version
+      placeholder: Arduino Uno / Arduino AVR Boards 1.8.6
+    validations:
+      required: true
+  - type: textarea
+    id: circuit
+    attributes:
+      label: Circuit and power details
+      description: For motor exercises, include the driver and supply ratings.
+    validations:
+      required: true
+  - type: textarea
+    id: reproduction
+    attributes:
+      label: Reproduction and observed behavior
+    validations:
+      required: true
diff --git a/.github/ISSUE_TEMPLATE/config.yml b/.github/ISSUE_TEMPLATE/config.yml
new file mode 100644
index 0000000..7df5262
--- /dev/null
+++ b/.github/ISSUE_TEMPLATE/config.yml
@@ -0,0 +1,5 @@
+blank_issues_enabled: false
+contact_links:
+  - name: Private security report
+    url: https://github.com/devkyato/Arduino-Programs-Guide/security/advisories/new
+    about: Report software vulnerabilities privately.
diff --git a/.github/ISSUE_TEMPLATE/lesson.yml b/.github/ISSUE_TEMPLATE/lesson.yml
new file mode 100644
index 0000000..21904ae
--- /dev/null
+++ b/.github/ISSUE_TEMPLATE/lesson.yml
@@ -0,0 +1,23 @@
+name: Lesson improvement
+description: Propose a clearer explanation, test, diagram, or challenge.
+title: "[Lesson]: "
+labels: ["documentation"]
+body:
+  - type: input
+    id: lesson
+    attributes:
+      label: Lesson
+    validations:
+      required: true
+  - type: textarea
+    id: confusion
+    attributes:
+      label: What is unclear or missing?
+    validations:
+      required: true
+  - type: textarea
+    id: proposal
+    attributes:
+      label: Proposed improvement
+    validations:
+      required: true
diff --git a/.github/PULL_REQUEST_TEMPLATE.md b/.github/PULL_REQUEST_TEMPLATE.md
new file mode 100644
index 0000000..8b3917b
--- /dev/null
+++ b/.github/PULL_REQUEST_TEMPLATE.md
@@ -0,0 +1,14 @@
+## Learning outcome
+
+<!-- What becomes safer, clearer, or more useful for a student? -->
+
+## Verification
+
+- [ ] Changed sketches compile for Arduino Uno
+- [ ] Matching lesson documentation is updated
+- [ ] No blocking delay was added to interactive behavior
+- [ ] Hardware/power details are included when applicable
+
+## Hardware tested
+
+<!-- Board, core, driver, supply, wiring, or "Not hardware-tested". -->
diff --git a/.github/dependabot.yml b/.github/dependabot.yml
new file mode 100644
index 0000000..478231b
--- /dev/null
+++ b/.github/dependabot.yml
@@ -0,0 +1,9 @@
+version: 2
+updates:
+  - package-ecosystem: github-actions
+    directory: /
+    schedule:
+      interval: monthly
+    groups:
+      actions:
+        patterns: ["*"]
diff --git a/.github/workflows/compile.yml b/.github/workflows/compile.yml
new file mode 100644
index 0000000..384c002
--- /dev/null
+++ b/.github/workflows/compile.yml
@@ -0,0 +1,37 @@
+name: Sketch compilation
+
+on:
+  push:
+    branches: [main]
+  pull_request:
+  workflow_dispatch:
+
+permissions:
+  contents: read
+
+jobs:
+  compile-uno:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v7
+      - uses: arduino/compile-sketches@v1
+        with:
+          fqbn: arduino:avr:uno
+          libraries: "[]"
+          sketch-paths: |
+            - exercises
+            - extras
+          enable-warnings-report: true
+
+  offline-package:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v7
+      - uses: actions/setup-python@v7
+        with:
+          python-version: "3.14"
+      - run: python tools/build_release.py
+      - uses: actions/upload-artifact@v6
+        with:
+          name: Arduino-Programs-Guide
+          path: dist/*.zip
diff --git a/.github/workflows/release.yml b/.github/workflows/release.yml
new file mode 100644
index 0000000..42e3071
--- /dev/null
+++ b/.github/workflows/release.yml
@@ -0,0 +1,25 @@
+name: Release
+
+on:
+  push:
+    tags: ["v*"]
+
+permissions:
+  contents: write
+
+jobs:
+  release:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v7
+      - uses: actions/setup-python@v7
+        with:
+          python-version: "3.14"
+      - name: Verify tag
+        shell: bash
+        run: test "$GITHUB_REF_NAME" = "v$(cat VERSION)"
+      - run: python tools/build_release.py
+      - name: Publish release
+        env:
+          GH_TOKEN: ${{ github.token }}
+        run: gh release create "$GITHUB_REF_NAME" dist/*.zip --generate-notes --verify-tag
diff --git a/.gitignore b/.gitignore
new file mode 100644
index 0000000..5deb25e
--- /dev/null
+++ b/.gitignore
@@ -0,0 +1,7 @@
+.vscode/
+build/
+dist/
+*.hex
+*.elf
+*.bin
+*.map
diff --git a/tools/build_release.py b/tools/build_release.py
new file mode 100644
index 0000000..b6c7be6
--- /dev/null
+++ b/tools/build_release.py
@@ -0,0 +1,56 @@
+"""Build a deterministic offline course archive."""
+
+from __future__ import annotations
+
+import zipfile
+from pathlib import Path
+
+ROOT = Path(__file__).resolve().parents[1]
+DIST = ROOT / "dist"
+INCLUDED = (
+    "exercises",
+    "extras",
+    "docs",
+    "README.md",
+    "CHANGELOG.md",
+    "CONTRIBUTING.md",
+    "CODE_OF_CONDUCT.md",
+    "SECURITY.md",
+    "LICENSE",
+    "VERSION",
+)
+FIXED_TIME = (2026, 1, 1, 0, 0, 0)
+
+
+def main() -> None:
+    version = (ROOT / "VERSION").read_text(encoding="utf-8").strip()
+    output = DIST / f"Arduino-Programs-Guide-{version}.zip"
+    DIST.mkdir(exist_ok=True)
+
+    files: list[Path] = []
+    for name in INCLUDED:
+        path = ROOT / name
+        files.extend(
+            (candidate for candidate in path.rglob("*") if candidate.is_file())
+            if path.is_dir()
+            else (path,)
+        )
+
+    with zipfile.ZipFile(output, "w", zipfile.ZIP_DEFLATED) as archive:
+        for path in sorted(files, key=lambda item: item.as_posix()):
+            relative = path.relative_to(ROOT).as_posix()
+            info = zipfile.ZipInfo(f"Arduino-Programs-Guide/{relative}", FIXED_TIME)
+            info.compress_type = zipfile.ZIP_DEFLATED
+            info.external_attr = 0o100644 << 16
+            archive.writestr(info, path.read_bytes())
+
+    with zipfile.ZipFile(output) as archive:
+        sketches = [name for name in archive.namelist() if name.endswith(".ino")]
+        if len(sketches) != 7:
+            raise RuntimeError(f"expected 7 sketches, found {len(sketches)}")
+
+    print(output)
+
+
+if __name__ == "__main__":
+    main()

From 41d615af00f04728654fb40ef5c6731666c35fba Mon Sep 17 00:00:00 2001
From: "@dev.mako" <prinz.jewel11@gmail.com>
Date: Wed, 29 Jul 2026 10:17:34 +0800
Subject: [PATCH 4/4] fix: match Arduino sketch names to their folders

---
 .github/ISSUE_TEMPLATE/bug.yml                                  | 2 +-
 ...e_a_arrow_controller.ino => exercise-a-arrow-controller.ino} | 0
 ...b_multi_led_pattern.ino => exercise-b-multi-led-pattern.ino} | 0
 .../{exercise_c_smart_fan.ino => exercise-c-smart-fan.ino}      | 0
 ...e_d_wheel_simulation.ino => exercise-d-wheel-simulation.ino} | 0
 ...er_motor_sync.ino => exercise-e-knight-rider-motor-sync.ino} | 0
 ...m_integration.ino => exercise-f-full-system-integration.ino} | 0
 .../{basic_bluetooth_led.ino => basic-bluetooth-led.ino}        | 0
 8 files changed, 1 insertion(+), 1 deletion(-)
 rename exercises/exercise-a-arrow-controller/{exercise_a_arrow_controller.ino => exercise-a-arrow-controller.ino} (100%)
 rename exercises/exercise-b-multi-led-pattern/{exercise_b_multi_led_pattern.ino => exercise-b-multi-led-pattern.ino} (100%)
 rename exercises/exercise-c-smart-fan/{exercise_c_smart_fan.ino => exercise-c-smart-fan.ino} (100%)
 rename exercises/exercise-d-wheel-simulation/{exercise_d_wheel_simulation.ino => exercise-d-wheel-simulation.ino} (100%)
 rename exercises/exercise-e-knight-rider-motor-sync/{exercise_e_knight_rider_motor_sync.ino => exercise-e-knight-rider-motor-sync.ino} (100%)
 rename exercises/exercise-f-full-system-integration/{exercise_f_full_system_integration.ino => exercise-f-full-system-integration.ino} (100%)
 rename extras/basic-bluetooth-led/{basic_bluetooth_led.ino => basic-bluetooth-led.ino} (100%)

diff --git a/.github/ISSUE_TEMPLATE/bug.yml b/.github/ISSUE_TEMPLATE/bug.yml
index 79b8756..ed166ab 100644
--- a/.github/ISSUE_TEMPLATE/bug.yml
+++ b/.github/ISSUE_TEMPLATE/bug.yml
@@ -7,7 +7,7 @@ body:
     id: lesson
     attributes:
       label: Lesson and sketch
-      placeholder: Exercise B / exercise_b_multi_led_pattern.ino
+      placeholder: Exercise B / exercise-b-multi-led-pattern.ino
     validations:
       required: true
   - type: input
diff --git a/exercises/exercise-a-arrow-controller/exercise_a_arrow_controller.ino b/exercises/exercise-a-arrow-controller/exercise-a-arrow-controller.ino
similarity index 100%
rename from exercises/exercise-a-arrow-controller/exercise_a_arrow_controller.ino
rename to exercises/exercise-a-arrow-controller/exercise-a-arrow-controller.ino
diff --git a/exercises/exercise-b-multi-led-pattern/exercise_b_multi_led_pattern.ino b/exercises/exercise-b-multi-led-pattern/exercise-b-multi-led-pattern.ino
similarity index 100%
rename from exercises/exercise-b-multi-led-pattern/exercise_b_multi_led_pattern.ino
rename to exercises/exercise-b-multi-led-pattern/exercise-b-multi-led-pattern.ino
diff --git a/exercises/exercise-c-smart-fan/exercise_c_smart_fan.ino b/exercises/exercise-c-smart-fan/exercise-c-smart-fan.ino
similarity index 100%
rename from exercises/exercise-c-smart-fan/exercise_c_smart_fan.ino
rename to exercises/exercise-c-smart-fan/exercise-c-smart-fan.ino
diff --git a/exercises/exercise-d-wheel-simulation/exercise_d_wheel_simulation.ino b/exercises/exercise-d-wheel-simulation/exercise-d-wheel-simulation.ino
similarity index 100%
rename from exercises/exercise-d-wheel-simulation/exercise_d_wheel_simulation.ino
rename to exercises/exercise-d-wheel-simulation/exercise-d-wheel-simulation.ino
diff --git a/exercises/exercise-e-knight-rider-motor-sync/exercise_e_knight_rider_motor_sync.ino b/exercises/exercise-e-knight-rider-motor-sync/exercise-e-knight-rider-motor-sync.ino
similarity index 100%
rename from exercises/exercise-e-knight-rider-motor-sync/exercise_e_knight_rider_motor_sync.ino
rename to exercises/exercise-e-knight-rider-motor-sync/exercise-e-knight-rider-motor-sync.ino
diff --git a/exercises/exercise-f-full-system-integration/exercise_f_full_system_integration.ino b/exercises/exercise-f-full-system-integration/exercise-f-full-system-integration.ino
similarity index 100%
rename from exercises/exercise-f-full-system-integration/exercise_f_full_system_integration.ino
rename to exercises/exercise-f-full-system-integration/exercise-f-full-system-integration.ino
diff --git a/extras/basic-bluetooth-led/basic_bluetooth_led.ino b/extras/basic-bluetooth-led/basic-bluetooth-led.ino
similarity index 100%
rename from extras/basic-bluetooth-led/basic_bluetooth_led.ino
rename to extras/basic-bluetooth-led/basic-bluetooth-led.ino