diff --git a/.github/.gitignore b/.github/.gitignore
deleted file mode 100644
index 8b13789..0000000
--- a/.github/.gitignore
+++ /dev/null
@@ -1 +0,0 @@
-
diff --git a/.github/actions/avr_setup/action.yml b/.github/actions/avr_setup/action.yml
new file mode 100644
index 0000000..3b92db0
--- /dev/null
+++ b/.github/actions/avr_setup/action.yml
@@ -0,0 +1,18 @@
+name: "Get changed files list"
+description: "Setup Node with caching for dependencies"
+runs:
+  using: "composite"
+  steps:
+    - name: Set up Arduino CLI
+      uses: arduino/setup-arduino-cli@v2
+
+    - name: Install platform
+      run: |
+        arduino-cli core update-index
+        arduino-cli core install ${{ env.platform }}
+      shell: bash
+
+    - name: Install popular libs
+      run: |
+        arduino-cli lib install LiquidCrystal
+      shell: bash
\ No newline at end of file
diff --git a/.github/actions/get_changed_files/action.yml b/.github/actions/get_changed_files/action.yml
new file mode 100644
index 0000000..ecf73ac
--- /dev/null
+++ b/.github/actions/get_changed_files/action.yml
@@ -0,0 +1,13 @@
+name: "Get changed files list"
+description: "Setup Node with caching for dependencies"
+runs:
+  using: "composite"
+  steps:
+    - name: Get changed files list
+      id: get_changed_files
+      run: |
+        echo "Changed files:"
+        git diff --name-only ${{ github.event.pull_request.base.sha }} > changed_files.txt
+        cat changed_files.txt
+        echo "The list is saved to changed_files.txt"
+      shell: bash
\ No newline at end of file
diff --git a/.github/workflows/Lab_01_CI.yml b/.github/workflows/Lab_01_CI.yml
deleted file mode 100644
index 985573b..0000000
--- a/.github/workflows/Lab_01_CI.yml
+++ /dev/null
@@ -1,37 +0,0 @@
-name: Cheking of compile Arduino sketch for AVR/AtMega and ESP8266
-
-on:
-  push:
-    branches: [ main, master ]
-  pull_request:
-    branches: [ main, master ]
-
-jobs:
-  test-matrix:
-    strategy:
-      matrix:
-        arduino-platform:
-          - "arduino:avr"
-          - "esp8266:esp8266"
-        include:
-          - arduino-platform: "arduino:avr"
-            fqbn: "arduino:avr:mega"
-          - arduino-platform: "esp8266:esp8266"
-            fqbn: "esp8266:esp8266:generic"
-
-    runs-on: ubuntu-22.04
-
-    steps:
-      - name: Checkout code
-        uses: actions/checkout@v4
-
-      - name: Set up Arduino CLI
-        uses: arduino/setup-arduino-cli@v2
-
-      - name: Install platform
-        run: |
-          arduino-cli core update-index
-          arduino-cli core install ${{ matrix.arduino-platform }}
-
-      - name: Compile Sketch
-        run: arduino-cli compile --fqbn ${{ matrix.fqbn }} ./mc_labs/mc_lab_01/*.ino
diff --git a/.github/workflows/lab-validation.yml b/.github/workflows/lab-validation.yml
new file mode 100644
index 0000000..059343b
--- /dev/null
+++ b/.github/workflows/lab-validation.yml
@@ -0,0 +1,114 @@
+name: Cheking of compile Arduino sketch for AVR/AtMega
+
+on:
+  pull_request:
+    branches: [main, master]
+
+env:
+  platform: "arduino:avr"
+  fqbn_master: "arduino:avr:mega"
+  COMMIT_COUNT: $(( ${{ github.event_name == 'pull_request' && github.event.pull_request.commits || 0 }} + 1 ))
+
+jobs:
+  handle_bad_branch_name:
+    runs-on: ubuntu-22.04
+    if: (contains(github.head_ref, 'mc_lab_1') || contains(github.head_ref, 'mc_lab_2') || contains(github.head_ref, 'mc_lab_3') || contains(github.head_ref, 'mc_lab_4') || contains(github.head_ref, 'mc_lab_5') || contains(github.head_ref, 'mc_lab_6') || contains(github.head_ref, 'mc_lab_7')) == false
+    steps:
+      - name: Fail the build
+        run: | 
+          echo "The branch name is not correct. It should contain 'mc_lab_' prefix"
+          exit 1
+  build_labs_1_to_4:
+    runs-on: ubuntu-22.04
+    if: contains(github.head_ref, 'mc_lab_1') || contains(github.head_ref, 'mc_lab_2') || contains(github.head_ref, 'mc_lab_3') || contains(github.head_ref, 'mc_lab_4')
+    steps:
+      - name: Checkout
+        uses: actions/checkout@v4
+        with:
+          fetch-depth: ${{ env.COMMIT_COUNT }}
+
+      - name: Get changed files list
+        uses: ./.github/actions/get_changed_files
+
+      - name: Set up Arduino CLI
+        uses: ./.github/actions/avr_setup
+
+      - name: Compile Sketch
+        run: arduino-cli compile --fqbn ${{ env.fqbn_master }} $(grep -E '\.ino$' changed_files.txt | xargs)
+  build_lab_5:
+    runs-on: ubuntu-22.04
+    if: contains(github.head_ref, 'mc_lab_5')
+    env:
+      fqbn_slave: "arduino:avr:nano"
+    steps:
+      - name: Checkout
+        uses: actions/checkout@v4
+        with:
+          fetch-depth: ${{ env.COMMIT_COUNT }}
+
+      - name: Get changed files list
+        uses: ./.github/actions/get_changed_files
+
+      - name: Get master folder
+        run: |
+          cat changed_files.txt | xargs dirname | grep 'master' | grep -m 1 -vE '/(.*master.*|.*slave.*)/'  > master_project.txt
+          echo "Master project:"
+          cat master_project.txt
+
+      - name: Get slave folders
+        run: |
+          cat changed_files.txt | xargs dirname | grep 'slave' | grep -vE '/(.*master.*|.*slave.*)/'  > slave_projects.txt
+          echo "Slave projects:"
+          cat slave_projects.txt
+
+      - name: Check if there is at least one master and one slave project
+        run: |
+          if [ ! -s master_project.txt ] || [ ! -s slave_projects.txt ]; then
+            echo "There is no master or slave project"
+            exit 1
+          fi
+
+      - name: Set up Arduino CLI
+        uses: ./.github/actions/avr_setup
+
+      - name: Compile master
+        run: while read master_folder; do arduino-cli compile --fqbn ${{ env.fqbn_master }} $master_folder/*.ino; done < master_project.txt
+
+      - name: Compile slaves
+        run: while read slave_folder; do arduino-cli compile --fqbn ${{ env.fqbn_slave }} $slave_folder/*.ino; done < slave_projects.txt
+  build_lab_6:
+    runs-on: ubuntu-22.04
+    if: contains(github.head_ref, 'mc_lab_6')
+    steps:
+      - name: Checkout
+        uses: actions/checkout@v4
+        with:
+          fetch-depth: ${{ env.COMMIT_COUNT }}
+
+      - name: It just passes
+        run: echo "It just passes. It's too complex"
+  build_lab_7:
+    runs-on: ubuntu-22.04
+    if: contains(github.head_ref, 'mc_lab_7')
+    env:
+      register-bindings: "m2560def.inc"
+    steps:
+      - name: Checkout
+        uses: actions/checkout@v4
+        with:
+          fetch-depth: ${{ env.COMMIT_COUNT }}
+
+      - name: Get changed files list
+        uses: ./.github/actions/get_changed_files
+
+      - name: Setup AVRA Assembler
+        run: |
+          git clone https://github.com/Ro5bert/avra.git
+          cd avra
+          sudo make install
+
+      - name: Preprocess sketch - append register bindings to the top of the file
+        run: printf ".include \"${{ env.register-bindings }}\"\n\n" | cat - $(grep -m 1 -E '\.(asm|S)$' changed_files.txt | xargs) > pipeline_main_assembly_source_file.asm
+
+      - name: Compile Sketch
+        run: avra pipeline_main_assembly_source_file.asm
diff --git a/mc_labs/mc_lab_03/lab3-mko/keypad4x4.h b/mc_labs/mc_lab_03/lab3-mko/keypad4x4.h
new file mode 100644
index 0000000..c8595d3
--- /dev/null
+++ b/mc_labs/mc_lab_03/lab3-mko/keypad4x4.h
@@ -0,0 +1,184 @@
+#define DDR_KEYPAD DDRK
+#define PORT_KEYPAD PORTK
+#define PIN_KEYPAD PINK
+
+
+class Keypad {
+public:
+  bool pressed = false;
+  char d1, d2, d3, d4, dA, dB, dC, dD;
+  char columns[4];
+  char rows[4];
+  Keypad(char d1, char d2, char d3, char d4, char dA, char dB, char dC, char dD)
+    : columns({ d1, d2, d3, d4 }),
+      rows({ dA, dB, dC, dD }) {
+    this->d1 = d1;
+    this->d2 = d2;
+    this->d3 = d3;
+    this->d4 = d4;
+    this->dA = dA;
+    this->dB = dB;
+    this->dC = dC;
+    this->dD = dD;
+  }
+
+  bool init() {
+    for (char row : rows)
+      pinMode(row, OUTPUT);
+  
+
+    for (char column : columns)
+      pinMode(column, INPUT);
+  }
+
+  bool isPressed() {
+    return pressed;
+  }
+
+  char readKey() {
+    char* location = getPressedButtonLocation();
+
+    if (!pressed)
+      return '?';
+
+    delay(200);
+    return getKeyByLocation(location);
+  }
+
+private:
+  char* getPressedButtonLocation() {
+    char result[] = { 0, 0 };
+    for (char rowToRead : rows) {
+      for (char row : rows) {
+        digitalWrite(row, HIGH);
+        asm("nop");
+      }
+      char activeColumn;
+      for (char column : columns) {
+        pressed = digitalRead(column) == HIGH;
+        if (pressed)
+          activeColumn = column;
+      }
+
+
+      if (pressed) {
+        result[0] = rowToRead;
+        result[1] = activeColumn;
+      }
+    }
+
+    return result;
+  }
+
+  char getKeyByLocation(char location[2]) {
+    char key = '?';
+    if (location[0] == dA && location[2] == d1) key = '7';
+    if (location[0] == dB && location[2] == d1) key = '4';
+    if (location[0] == dC && location[2] == d1) key = '1';
+    if (location[0] == dD && location[2] == d1) key = 'F';
+    if (location[0] == dA && location[2] == d2) key = '8';
+    if (location[0] == dB && location[2] == d2) key = '5';
+    if (location[0] == dC && location[2] == d2) key = '2';
+    if (location[0] == dD && location[2] == d2) key = '0';
+    if (location[0] == dD && location[2] == d3) key = '9';
+    if (location[0] == dA && location[2] == d3) key = '6';
+    if (location[0] == dB && location[2] == d3) key = '3';
+    if (location[0] == dC && location[2] == d3) key = 'E';
+    if (location[0] == dD && location[2] == d4) key = 'A';
+    if (location[0] == dA && location[2] == d4) key = 'B';
+    if (location[0] == dB && location[2] == d4) key = 'C';
+    if (location[0] == dC && location[2] == d4) key = 'D';
+    return key;
+  }
+};
+
+const int Key_1 = B10111110;
+const int Key_2 = B10111101;
+const int Key_3 = B10111011;
+const int Key_A = B11100111;
+
+const int Key_4 = B11011110;
+const int Key_5 = B11011101;
+const int Key_6 = B11011011;
+const int Key_B = B11010111;
+
+const int Key_7 = B11101110;
+const int Key_8 = B11101101;
+const int Key_9 = B11101011;
+const int Key_C = B10110111;
+
+const int Key_F = B01111110;
+const int Key_0 = B01111101;
+const int Key_E = B01111011;
+const int Key_D = B01110111;
+
+unsigned char freePinFromKeyPad = 1;
+unsigned char keyFromKeyPad = 1;
+char pressedButton = 0;
+bool logicPressed = false;
+
+void initKeyPad() {
+  DDR_KEYPAD = 0x0F;
+  PORT_KEYPAD = 0xF0;
+}
+
+char readKeyFromPad4x4() {
+  logicPressed = false;
+  return pressedButton;
+}
+
+bool isButtonPressed() {
+  if (freePinFromKeyPad == 1)  //перевірка чи була натиснута кнопка
+  {                            //якщо =1, тоді ще не натискалася
+    if (PIN_KEYPAD != 0xF0) {
+      delay(50);
+      freePinFromKeyPad = 0;
+      keyFromKeyPad = 1;
+      // Визначення натиснутої клавіші
+      // почергова подача 0V на рядки клавіатури A,B,C,D
+      PORT_KEYPAD = B11111110;  // A-рядок
+      asm("nop");
+      if (PORT_KEYPAD == PIN_KEYPAD) {
+        PORT_KEYPAD = B11111101;  // B-рядок
+        asm("nop");
+        if (PORT_KEYPAD == PIN_KEYPAD) {
+          PORT_KEYPAD = B11111011;  // C-рядок
+          asm("nop");
+          if (PORT_KEYPAD == PIN_KEYPAD) {
+            PORT_KEYPAD = B11110111;  // D-рядок
+            asm("nop");
+            if (PORT_KEYPAD == PIN_KEYPAD)
+              keyFromKeyPad = 0;  // жодна клавіша не натиснута
+          }
+        }
+      }
+      if (keyFromKeyPad == 1)  //визначення натиснутої клавіші
+      {
+        if (PIN_KEYPAD == Key_1) pressedButton = '1';
+        else if (PIN_KEYPAD == Key_2) pressedButton = '2';
+        else if (PIN_KEYPAD == Key_3) pressedButton = '3';
+        else if (PIN_KEYPAD == Key_4) pressedButton = '4';
+        else if (PIN_KEYPAD == Key_5) pressedButton = '5';
+        else if (PIN_KEYPAD == Key_6) pressedButton = '6';
+        else if (PIN_KEYPAD == Key_7) pressedButton = '7';
+        else if (PIN_KEYPAD == Key_8) pressedButton = '8';
+        else if (PIN_KEYPAD == Key_9) pressedButton = '9';
+        else if (PIN_KEYPAD == Key_0) pressedButton = '0';
+        else if (PIN_KEYPAD == Key_A) pressedButton = 'A';
+        else if (PIN_KEYPAD == Key_B) pressedButton = 'B';
+        else if (PIN_KEYPAD == Key_C) pressedButton = 'C';
+        else if (PIN_KEYPAD == Key_D) pressedButton = 'D';
+        else if (PIN_KEYPAD == Key_E) pressedButton = 'E';
+        else if (PIN_KEYPAD == Key_F) pressedButton = 'F';
+        logicPressed = true;
+      }
+
+      PORT_KEYPAD = 0xF0;  //відновлюємо порт
+    }
+  } else if (PIN_KEYPAD == 0xF0)  //перевіряємо чи кнопка відпущена
+  {
+    delay(200);
+    freePinFromKeyPad = 1;
+  }
+  return logicPressed;
+}
diff --git a/mc_labs/mc_lab_03/lab3-mko/lab3-mko.ino b/mc_labs/mc_lab_03/lab3-mko/lab3-mko.ino
new file mode 100644
index 0000000..f1c42c1
--- /dev/null
+++ b/mc_labs/mc_lab_03/lab3-mko/lab3-mko.ino
@@ -0,0 +1,203 @@
+
+
+// include the library code:
+#include "keypad4x4.h"
+#include <LiquidCrystal.h>
+
+#define RESET -1
+#define RETRIEVE -2
+
+enum ClockMode {
+  Time,
+  Alarm,
+  AlarmSetup,
+  TimeSetup
+};
+
+const PROGMEM char sixty[60][2] = {
+  "00", "01", "02", "03", "04", "05", "06", "07", "08", "09",
+  "10", "11", "12", "13", "14", "15", "16", "17", "18", "19",
+  "20", "21", "22", "23", "24", "25", "26", "27", "28", "29",
+  "30", "31", "32", "33", "34", "35", "36", "37", "38", "39",
+  "40", "41", "42", "43", "44", "45", "46", "47", "48", "49",
+  "50", "51", "52", "53", "54", "55", "56", "57", "58", "59"
+};
+
+
+// initialize the library by associating any needed LCD interface pin
+// with the arduino pin number it is connected to
+const int padPins[] = { 62, 63, 64, 65, 66, 67, 98, 69 };
+const int rs = 22, rw = PJ6, en = 23;
+const int ds[] = { 49, 48, 47, 46, 45, 44, 43, 42 };
+const int buzzerPin = 24;
+
+long time = 0;
+long alarm = 0;
+bool alarmActive = false;
+bool previousAlarmSetFailed = false;
+char mode = ClockMode::Time;
+int inputData = 0;
+
+LiquidCrystal lcd(rs, en, ds[0], ds[1], ds[2], ds[3], ds[4], ds[5], ds[6], ds[7]);
+
+ISR(TIMER1_COMPA_vect) {
+  time++;
+}
+
+String makeStr(String str) {
+  while(str.length() < 16) {
+    str += ' ';
+  }
+  return str;
+}
+
+String secondsToTime(long time) {
+  String timeFormat = "00:00:00";
+
+  long hoursMinutesSeconds[] = { (time / (60 * 60)) % 24, (time / 60) % 60, time % 60 };
+
+  for (int i = 0; i < 3; i++) {
+    for (int j = 0; j < 2; j++) {
+      timeFormat[i * 3 + j] = (char)pgm_read_byte(&(sixty[hoursMinutesSeconds[i]][j]));
+    }
+  }
+
+  return timeFormat;
+}
+
+void handleButtonPress() {
+  if (isButtonPressed()) {
+    char value = readKeyFromPad4x4();
+    switch (value) {
+      case 'A':
+        mode = ClockMode::TimeSetup;
+        getTime(RESET);
+        break;
+      case 'B':
+        mode = ClockMode::AlarmSetup;
+        getTime(RESET);
+        break;
+      case 'C':
+        mode = ClockMode::Alarm;
+        break;
+      case 'D':
+        if( mode == ClockMode::Alarm)
+        alarmActive = !alarmActive;
+        break;
+      case 'E':
+        if(mode == ClockMode::TimeSetup) {
+          mode = ClockMode::Time;
+          time = getTime(RETRIEVE);  
+        } else if(mode == ClockMode::AlarmSetup) {
+          mode = ClockMode::Alarm;
+          alarm = getTime(RETRIEVE);  
+        }    
+        break;
+      case 'F':
+        mode = ClockMode::Time;
+        break;
+      default:
+        if(mode != ClockMode::TimeSetup &&
+           mode != ClockMode::AlarmSetup) break;
+        
+        getTime(int(value - '0'));
+        break;
+    }
+  }
+}
+
+void displayTime(long seconds) {
+  lcd.setCursor(0, 1);
+
+  // print the number of seconds since reset:
+  lcd.print(makeStr(secondsToTime(seconds)));
+}
+
+
+long getTime(int inputNumber) {
+  static int currentValue[] = { 0, 0, 0, 0, 0, 0 };
+  static int currentSymbol = 0;
+
+  if(inputNumber == RESET) {
+    currentSymbol = 0;
+    for(int i = 0; i < 6; i++)
+      currentValue[i] = 0;
+    
+    displayTime(0);
+    return 0;
+  } 
+  
+  int previousNumber = currentValue[currentSymbol];
+  if(inputNumber != RETRIEVE) 
+    currentValue[currentSymbol] = inputNumber;
+  
+
+  long hours = (currentValue[0] * 10 + currentValue[1]);
+  long minutes = (currentValue[2] * 10 + currentValue[3]);
+  long seconds = (currentValue[4] * 10 + currentValue[5]);
+
+  if(hours >= 24 || minutes >= 60 || seconds >= 60) {
+    currentValue[currentSymbol] = previousNumber;   
+    return -1;
+  }
+
+  long currentTime = (hours * 3600) + (minutes * 60) + seconds;
+
+  if(inputNumber != RETRIEVE) {
+    displayTime(currentTime);
+    currentSymbol = (++currentSymbol) % 6;
+  }
+
+  return currentTime;
+}
+
+void checkAlarm() {
+  digitalWrite(buzzerPin, (alarmActive && ((time - alarm) % 2 == 0) && ((time - alarm) < 30) && ((time - alarm) > 0)) ? HIGH : LOW);
+}
+
+void handleCurrentMode() {
+  lcd.setCursor(0, 0);
+  switch (mode) {
+    case ClockMode::TimeSetup:
+      lcd.print(makeStr("set time:"));
+      break;
+    case ClockMode::AlarmSetup:
+      lcd.print(makeStr("set alarm:"));
+      break;
+    case ClockMode::Alarm:
+      lcd.print(makeStr("alarm" + String(alarmActive ? " on" : " off") + ":"));
+      displayTime(alarm);
+      break;
+    case ClockMode::Time:
+      lcd.print(makeStr("time" + String(alarmActive ? ", alarm on" : "") + ":"));
+      displayTime(time);
+      break;
+  }
+}
+
+
+void setup() {
+
+  initKeyPad();
+
+  noInterrupts();
+
+  // Таймер#1: Скид при співпадінні OCR1A (1sec)
+  TCCR1A = 0x00;
+  TCCR1B = (1 << WGM12) | (1 << CS12) | (1 << CS10);  //CTC mode & Prescaler @ 1024
+  TIMSK1 = (1 << OCIE1A);                             // дозвіл на переривання по співпадінню
+  OCR1A = 0x3D08;                                     // compare value = 1 sec (16MHz AVR)
+
+  interrupts();
+
+  // set up the LCD's number of columns and rows:
+  lcd.begin(16, 2);
+
+  pinMode(buzzerPin, OUTPUT);
+}
+
+void loop() {
+  checkAlarm();
+  handleButtonPress();
+  handleCurrentMode();
+}
\ No newline at end of file
diff --git a/mc_labs/mc_lab_03/lab3-mko/lab3.pdsprj b/mc_labs/mc_lab_03/lab3-mko/lab3.pdsprj
new file mode 100644
index 0000000..c7b869f
Binary files /dev/null and b/mc_labs/mc_lab_03/lab3-mko/lab3.pdsprj differ