diff --git a/Homework/Homework4/Bluetooth/Bluetooth.ino b/Homework/Homework4/Bluetooth/Bluetooth.ino
new file mode 100644
index 0000000..7673be4
--- /dev/null
+++ b/Homework/Homework4/Bluetooth/Bluetooth.ino
@@ -0,0 +1,38 @@
+#include "SoftwareSerial.h"
+
+const byte rx_connected = 11;
+const byte tx_connected = 10;
+
+SoftwareSerial soft_serial(tx_connected, rx_connected);
+
+void setup() {
+    pinMode(tx_connected, INPUT);
+    pinMode(rx_connected, OUTPUT);
+    Serial.begin(9600);
+    soft_serial.begin(9600);
+}
+
+void loop() {
+    if (Serial.available()) {
+        char ch = Serial.read();
+        Serial.print(ch);
+        soft_serial.print(ch);
+    }
+    if (soft_serial.available()) {
+        char ch = soft_serial.read();
+        Serial.print(ch);
+        soft_serial.print(ch);
+    }
+    Serial.println("A loop");
+    // Serial.println("A loop");
+    // if (soft_serial.availableForWrite()) {
+    //     Serial.println("Available");
+    // }
+    // else {
+    //     Serial.println("Unavailable");
+    // }
+    // if (Serial.availableForWrite()) {
+    //     Serial.println("Can Write");
+    // }
+    delay(1000);
+}
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diff --git a/Homework/Homework4/OLED/OLED.ino b/Homework/Homework4/OLED/OLED.ino
new file mode 100644
index 0000000..794f1a2
--- /dev/null
+++ b/Homework/Homework4/OLED/OLED.ino
@@ -0,0 +1,43 @@
+#include "U8glib.h"
+
+U8GLIB_SSD1306_128X32 u8g(U8G_I2C_OPT_NONE);	// I2C / TWI
+
+void draw(void) {
+  // graphic commands to redraw the complete screen should be placed here  
+  u8g.setFont(u8g_font_courR18);
+  //u8g.setFont(u8g_font_osb21);
+  u8g.drawStr( 0, 14, "Hello World!");
+}
+
+void setup(void) {
+  // flip screen, if required
+  // u8g.setRot180();
+  
+  // set SPI backup if required
+  //u8g.setHardwareBackup(u8g_backup_avr_spi);
+
+  // assign default color value
+  if ( u8g.getMode() == U8G_MODE_R3G3B2 ) {
+    u8g.setColorIndex(255);     // white
+  }
+  else if ( u8g.getMode() == U8G_MODE_GRAY2BIT ) {
+    u8g.setColorIndex(3);         // max intensity
+  }
+  else if ( u8g.getMode() == U8G_MODE_BW ) {
+    u8g.setColorIndex(1);         // pixel on
+  }
+  else if ( u8g.getMode() == U8G_MODE_HICOLOR ) {
+    u8g.setHiColorByRGB(255,255,255);
+  }
+}
+
+void loop(void) {
+  // picture loop
+  u8g.firstPage();  
+  do {
+    draw();
+  } while( u8g.nextPage() );
+  
+  // rebuild the picture after some delay
+  //delay(50);
+}
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