diff --git a/section_3/Makefile b/section_3/Makefile
new file mode 100644
index 0000000..f843fa4
--- /dev/null
+++ b/section_3/Makefile
@@ -0,0 +1,12 @@
+SOURCES = $(wildcard *.c)
+OBJETS = $(SOURCES:.c=.o)
+EXECUTABLE = arduino
+LDLIBS += -lutil
+CFLAGS += -Wall
+
+all: $(EXECUTABLE)
+
+$(EXECUTABLE): $(OBJETS)
+
+clean:
+	rm -rf $(EXECUTABLE) *.o
diff --git a/section_3/arduino.c b/section_3/arduino.c
new file mode 100644
index 0000000..e68b61e
--- /dev/null
+++ b/section_3/arduino.c
@@ -0,0 +1,159 @@
+/*
+ * Very basic emulation of an Arduino UNO with some buttons and some LEDs
+ */
+
+////
+// Include files
+////
+#include <stdio.h>
+#include <stdlib.h>
+#include <unistd.h>
+#include <string.h>
+#include <sys/poll.h>
+#include <sys/time.h>
+#include <stdbool.h>
+
+#include "virtual_serial.h"
+#include "arduino.h"
+
+////
+// Constants
+////
+#define		SERIAL_SPEED		9600
+#define		SLEEP_DELAY		100
+
+#define		MAX_NAME		1024
+#define		MAX_LINE		1024
+#define		MAX_SERIAL		1024
+
+////
+// Global variables
+////
+
+////
+// Utility functions
+////
+
+static unsigned char ledstates[LEDS_NB];
+void led(int num,unsigned char state){
+if(num>=0 && num<LEDS_NB) ledstates[num]=state;
+int i;
+printf("   LEDs: ");
+for(i=0;i<LEDS_NB;i++) printf("[%c] ",ledstates[i]?'X':' ');
+printf("\r");
+fflush(stdout);
+}
+
+static unsigned char outbuf[MAX_SERIAL];
+int outsize=0;
+void serialSend(unsigned char *data,int size){
+if(size+outsize<MAX_SERIAL){
+  memcpy(outbuf+outsize,data,size);
+  }
+}
+
+static unsigned char butstates[BUTTONS_NB];
+static void _button(int num,unsigned char state){
+if(num>=0 && num<BUTTONS_NB) butstates[num]=state;
+int i;
+printf("Buttons: ");
+for(i=0;i<BUTTONS_NB;i++) printf("[%c] ",(butstates[i]?'A':'a')+i);
+printf("\n");
+}
+
+unsigned char button(int num){
+if(num>=0 && num<BUTTONS_NB) return butstates[num];
+return 255;
+}
+
+long millis(void){
+struct timeval tv;
+gettimeofday(&tv,NULL);
+return tv.tv_sec*1000+tv.tv_usec/1000;
+}
+
+////
+// Events function
+////
+
+static void handleEvents(int sd){
+struct pollfd fds[2];
+char line[MAX_LINE];
+unsigned char packet[MAX_SERIAL];
+int ret;
+// my variables 
+int i;
+//
+fds[0].fd=STDIN_FILENO;
+fds[0].events=POLLIN;
+fds[1].fd=sd;
+fds[1].events=POLLIN;
+
+while(1){
+  
+  if (butstates[0] == 1)
+  {
+	
+	i = 0;
+	while (i <= BUTTONS_NB && butstates[i]) 
+		i += 1;
+	if(i <= BUTTONS_NB) loop();
+  }
+  ret=poll(fds,2,SLEEP_DELAY);
+  if(ret==-1){ perror("poll"); exit(EXIT_FAILURE); }
+  if(fds[0].revents&POLLIN){
+    if(fgets(line,MAX_LINE,stdin)==NULL){ perror("fgets"); exit(EXIT_FAILURE); } 
+#ifdef DEBUG
+    printf("keyboard: %s",line);
+#endif
+    int i;
+    for(i=0;i<strlen(line);i++){
+      if(line[i]>='a' && line[i]<='d') _button(line[i]-'a',0);
+      if(line[i]>='A' && line[i]<='D') _button(line[i]-'A',1);
+      }
+    }
+  if(fds[1].revents&POLLIN){
+    int nb;
+    if((nb=read(sd,packet,MAX_SERIAL))<=0) break;
+#ifdef DEBUG
+    printf("serial in: ");
+#endif
+    int i;
+    for(i=0;i<nb;i++){
+#ifdef DEBUG
+      printf("%02x ",packet[i]);
+#endif
+      serialInHandler(packet[i]);
+      }
+#ifdef DEBUG
+    printf("\n");
+#endif
+    }
+  if(outsize>0){
+    if(write(sd,outbuf,outsize)!=outsize) break;
+#ifdef DEBUG
+    printf("serial out: ");
+    int i;
+    for(i=0;i<outsize;i++){
+      printf("%02x ",outbuf[i]);
+      }
+    printf("\n");
+#endif
+    outsize=0;
+    }
+  }
+}
+
+////
+// Main function
+////
+
+int main(void){
+char name[MAX_NAME];
+int sd=virtualSerialOpen(name,SERIAL_SPEED);
+printf("Slave device is '%s'\n",name);
+setup();
+handleEvents(sd);
+virtualSerialClose(sd);
+exit(0);
+}
diff --git a/section_3/arduino.h b/section_3/arduino.h
new file mode 100644
index 0000000..25ccaad
--- /dev/null
+++ b/section_3/arduino.h
@@ -0,0 +1,26 @@
+/*
+ * Constants and prototype for Arduino simulator
+ */
+
+////
+// Constants
+////
+#define 	BUTTONS_NB		4
+#define		LEDS_NB			6
+
+////
+// Prototypes of defined fonctions
+////
+
+void led(int num,unsigned char state);
+unsigned char button(int num);
+void serialSend(unsigned char *data,int size);
+long millis(void);
+
+////
+// Prototypes of users handlers
+////
+
+void setup(void);
+void loop(void);
+void serialInHandler(unsigned char byte);
diff --git a/section_3/main.c b/section_3/main.c
new file mode 100644
index 0000000..58ad95b
--- /dev/null
+++ b/section_3/main.c
@@ -0,0 +1,37 @@
+/*
+ * Arduino program example
+ */
+
+////
+// Include files
+////
+#include "arduino.h"
+#include <stdio.h>
+////
+// Global variables
+// my variables 
+int i;
+long now;
+//
+////
+
+////
+// Handler functions
+///
+
+void setup(void){
+	i = 0;	
+}
+
+void loop(void){
+	led((i-1 + LEDS_NB) % LEDS_NB, 0);
+	led(i % LEDS_NB, 1);
+	now = millis();
+	while(millis() != now+300);
+	i = (i+1) %  LEDS_NB;
+	
+}
+
+
+void serialInHandler(unsigned char byte){
+}
diff --git a/section_3/virtual_serial.c b/section_3/virtual_serial.c
new file mode 100644
index 0000000..aa69b5a
--- /dev/null
+++ b/section_3/virtual_serial.c
@@ -0,0 +1,69 @@
+/*
+ * Virtual Serial library
+ */
+
+////
+// Include files
+////
+#include <stdio.h>
+#include <stdlib.h>
+#include <unistd.h>
+#include <termios.h>
+#include <strings.h>
+#include <sys/types.h>
+#include <sys/ioctl.h>
+#include <sys/file.h>
+#include <linux/serial.h>
+#include <pty.h>
+
+#include "virtual_serial.h"
+
+////
+// Functions
+////
+
+//
+// Serial structure filling
+//
+static struct termios serialConfig(int speed){
+int fspeed;
+switch(speed){
+  case 1200: fspeed=B1200; break;
+  case 2400: fspeed=B2400; break;
+  case 4800: fspeed=B4800; break;
+  case 9600: fspeed=B9600; break;
+  case 19200: fspeed=B19200; break;
+  case 38400: fspeed=B38400; break;
+  case 57600: fspeed=B57600; break;
+  case 115200: fspeed=B115200; break;
+  default: fprintf(stderr,"Unknown serial speed %d.\n",speed); exit(-1);
+  }
+struct termios new;
+bzero(&new,sizeof(new));
+new.c_cflag=CLOCAL|CREAD|fspeed|CS8;
+new.c_iflag=0;
+new.c_oflag=0;
+new.c_lflag=0;     /* set input mode (non-canonical, no echo,...) */
+new.c_cc[VTIME]=0; /* inter-character timer unused */
+new.c_cc[VMIN]=1;  /* blocking read until 1 char received */
+return new;
+}
+
+//
+// Virtual serial creation
+//
+
+int virtualSerialOpen(char *name,int speed){
+int master;
+int slave;
+struct termios serial=serialConfig(speed);
+openpty(&master,&slave,name,&serial,NULL);
+return master;
+}
+
+//
+// Serial port termination
+//
+void virtualSerialClose(int fd){
+close(fd);
+}
diff --git a/section_3/virtual_serial.h b/section_3/virtual_serial.h
new file mode 100644
index 0000000..20c91e6
--- /dev/null
+++ b/section_3/virtual_serial.h
@@ -0,0 +1,9 @@
+/*
+ * Public definitions for virtual serial library
+ */
+
+////
+// Public prototypes
+////
+int virtualSerialOpen(char *name,int speed);
+void virtualSerialClose(int fd);
--
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