diff --git a/.gitignore b/.gitignore
index c96066d..2608ec2 100644
--- a/.gitignore
+++ b/.gitignore
@@ -1 +1,2 @@
-/.DS_Store
\ No newline at end of file
+.DS_Store
+.vscode
\ No newline at end of file
diff --git a/Homework2/Homework2.ino b/Homework/Homework2/Homework2.ino
similarity index 100%
rename from Homework2/Homework2.ino
rename to Homework/Homework2/Homework2.ino
diff --git a/Homework/Homework3/Homework3.ino b/Homework/Homework3/Homework3.ino
new file mode 100644
index 0000000..5c7d662
--- /dev/null
+++ b/Homework/Homework3/Homework3.ino
@@ -0,0 +1,150 @@
+#include <LiquidCrystal.h>
+#define RESET 0x100
+#define READY 0x1
+#define BEGIN 0x2
+#define PAUSE 0x3
+#define STOP 0x4
+#define BEEPING 0x5
+#define STATUS_FIELD 0xf
+#define STATUS_CHANGED 0x10
+
+const int rs_pin = 13, en_pin = 12, d4_pin = 7, d5_pin = 6, d6_pin = 5, d7_pin = 4;
+const int switch_pin = 2;
+const int x_pin = A0, y_pin = A1;
+
+int status = 0;
+int last_tick;
+int last_start_tick = 0;
+int timed_length = 0;
+LiquidCrystal LCD(rs_pin, en_pin, d4_pin, d5_pin, d6_pin, d7_pin);
+
+
+void setup() {
+  // put your setup code here, to run once:
+  Serial.begin(9600);
+  pinMode(switch_pin, INPUT_PULLUP);
+  attachInterrupt(0, switch_pressed, FALLING);
+  LCD.begin(16, 2);
+}
+
+void loop() {
+  // put your main code here, to run repeatedly:
+
+  if (status & RESET) {
+    // Serial.println("Reset");
+    timed_length = 0;
+    LCD.clear();
+    LCD.setCursor(0, 0);
+    LCD.print("WAIT...");
+    status = READY | STATUS_CHANGED;
+    delay(1000);
+  } else {
+    switch (status & STATUS_FIELD) {
+      case READY:
+        {
+          // Serial.println("Ready");
+          if (status & STATUS_CHANGED) {
+            LCD.clear();
+            LCD.print("READY");
+            status = READY;
+          }
+          if (analogRead(y_pin) > 800) {
+            last_tick = millis();
+            status = BEGIN | STATUS_CHANGED;
+            last_start_tick = last_tick;
+          }
+          break;
+        }
+      case BEGIN:
+        {
+          // Serial.println("Begin");
+          if (status & STATUS_CHANGED) {
+            LCD.clear();
+            LCD.print("BEGIN");
+            // delay(500);
+            status = BEGIN;
+          }
+
+          delay(10);
+          int cur_tick = millis();
+          timed_length += cur_tick - last_tick;
+          last_tick = cur_tick;
+
+          if (timed_length > 10000) {
+            status = BEEPING | STATUS_CHANGED;
+            break;
+          }
+
+          Serial.println(timed_length / 10 * 10);
+          LCD.setCursor(0, 1);
+          LCD.print(timed_length);
+
+          if (analogRead(y_pin) > 800 && cur_tick - last_start_tick > 200) {
+            status = STOP | STATUS_CHANGED;
+            break;
+          }
+
+          if (analogRead(x_pin) > 800) {
+            status = PAUSE | STATUS_CHANGED;
+            break;
+          }
+          break;
+        }
+      case PAUSE:
+        {
+          // Serial.println("Pause");
+          if (status & STATUS_CHANGED) {
+            LCD.clear();
+            LCD.print("PAUSED");
+            LCD.setCursor(0, 1);
+            LCD.print(timed_length);
+            delay(500);
+            status = PAUSE;
+          }
+
+          if (analogRead(x_pin) < 200) {
+            status = BEGIN | STATUS_CHANGED;
+            last_tick = millis();
+            break;
+          }
+          break;
+        }
+      case STOP:
+        {
+          // Serial.println("Stop");
+          if (status & STATUS_CHANGED) {
+            LCD.clear();
+            LCD.print("STOPPED");
+            status = STOP;
+            break;
+          }
+          break;
+        }
+      case BEEPING:
+        {
+          // Serial.println("Beep");
+          if (status & STATUS_CHANGED) {
+            LCD.clear();
+            LCD.print("BEEP");
+            status = BEEPING;
+          }
+
+          int y_cmd = analogRead(x_pin);
+          if (y_cmd > 800) {
+            timed_length = 0;
+            status = READY | STATUS_CHANGED;
+          } else if (y_cmd < 200) {
+            timed_length = 0;
+            last_tick = millis();
+            status = BEGIN | STATUS_CHANGED;
+          }
+          break;
+        }
+    }
+  }
+}
+
+void switch_pressed() {
+  status = RESET;
+  Serial.println("Pressed");
+}