diff --git a/include/sound4calc.h b/include/sound4calc.h
index 73ee0a1..5e6e000 100644
--- a/include/sound4calc.h
+++ b/include/sound4calc.h
@@ -1,11 +1,15 @@
 #ifndef _SOUND4CALC_H
     #define _SOUND4CALC_H
 
-extern char wave_signal[25];
-extern unsigned short duration;
-extern unsigned int freq;
+extern struct Note
+{
+    char* wave_signal;
+    unsigned short duration;
+    unsigned int freq;
+} note;
 
 void CallSequence();
+void CallNote();
 void PutPinState(char level);
 void PlayNote();
 void InitPorts();
diff --git a/src/main.c b/src/main.c
index 7b5b4fc..1ffb0e0 100644
--- a/src/main.c
+++ b/src/main.c
@@ -1,15 +1,15 @@
 #include "main.h"
 #include "sound4calc.h"
-//#include <timer.h> // add timer fonction
-#include <display.h> // add display fonction
+#include <timer.h>
+#include <display.h>
 #include <keyboard.h>
-
+#include "string.h"
 //#define PI 3.141592653584
 
 int main(void)
 {
     unsigned int key = 0;
-    unsigned short place = 2;
+    unsigned short place = 0;
   //unsigned int i=0;
 
     InitPorts();
@@ -18,31 +18,34 @@ int main(void)
     {
         dclear();
 
-        dprint(1, 1, "%d", freq);
-        dprint(1, 10, "%s", wave_signal);
-        dprint(1, 20, "F1:note/F2:sequence", place);
+        dprint(1, 1, "%d", note.freq);
+        dprint(1, 10, "%s", note.wave_signal);
+        dprint(1, 20, "%d, %d", strlen(note.wave_signal), place);
+        dprint(1, 30, "F1:note/F2:sequence");
         dtext(1, 50, "F5 _    F6 -");
 
-
-
         dupdate();
 
         key = getkey();
 
         switch(key)
         {
-            case KEY_RIGHT : freq+=1; break;
-            case KEY_LEFT : freq-=1; break;
-            case KEY_UP : freq+=10; break;
-            case KEY_DOWN : freq-=10; break;
+            case KEY_RIGHT : note.freq+=1; break;
+            case KEY_LEFT : note.freq-=1; break;
+            case KEY_UP : note.freq+=10; break;
+            case KEY_DOWN : note.freq-=10; break;
 
-            case KEY_F5 : *(wave_signal+place++) = '_'; break;
-            case KEY_F6 : *(wave_signal+place++) = '-'; break;
-            case KEY_DEL : place=(place>0 ? place - 1 : 0); *(wave_signal+place) = 0; break;
+            case KEY_F5 : *(note.wave_signal+place++) = '_'; break;
+            case KEY_F6 : *(note.wave_signal+place++) = '-'; break;
+            case KEY_DEL : place=(place>0 ? place - 1 : 0); *(note.wave_signal+place) = 0; break;
 
             case KEY_F1 : CallNote(); break;
             case KEY_F2 : CallSequence(); break;
 
+            case KEY_EXE :
+                timer_start(TIMER_USER, note.freq * place, Clock_Hz, PlayNote, place * note.freq * note.duration / 1000);
+                break;
+
             case KEY_EXIT :
                 StopTimer();
                     return 1;
diff --git a/src/sound4calc.c b/src/sound4calc.c
index 6a4b3fe..741618b 100644
--- a/src/sound4calc.c
+++ b/src/sound4calc.c
@@ -2,6 +2,8 @@
 #include <mpu.h> // from Gint
 #include <timer.h> //from Gint
 
+static int strlen(char* str);
+
 static struct {
    	int freq;
     int length_ms;
@@ -12,30 +14,33 @@ static struct {
       {   -1,   -1 }
   };
 
-char wave_signal[25] = {0}; // simple waveform
-unsigned short duration = 2000; // equivalent as 2000 ms duration sound
-unsigned int freq = 440;
+struct Note note;
 
+/*
+    CallSequence()
+    make a little sound sequence
+*/
 void CallSequence()
 {
     static int length_end = 0;
-    static int note = -1  ;
+    static int notes = -1  ;
 
     if(length_end<=0)
     {
-        note++;
+        notes++;
 
         //Stop the timer
-        if(seq[note].freq < 0)
+        if(seq[notes].freq < 0)
         {
+            length_end = 0;
             timer_stop(TIMER_USER);
             return;
         }
 
         // update of the number of turn
-        length_end = seq[note].freq * seq[note].length_ms / 1000;
-
-        timer_start(TIMER_USER, 2 * seq[note].freq, Clock_Hz, CallSequence, 0);
+        length_end = strlen(note.wave_signal) * seq[notes].freq * seq[notes].length_ms / 1000;
+        // start or reload the timer
+        timer_start(TIMER_USER, 2 * seq[notes].freq, Clock_Hz, CallSequence, 0);
     }
 
     PlayNote();
@@ -44,38 +49,40 @@ void CallSequence()
 
 void CallNote()
 {
-    unsigned int wavelength = strlen(wave_signal);
-
-    timer_start(TIMER_USER, freq * wavelength, Clock_Hz, PlayNote, freq * duration / 1000);
+    note.duration = 1000;
+    timer_start(TIMER_USER, note.freq * strlen(note.wave_signal), Clock_Hz, PlayNote, strlen(note.wave_signal) * note.freq * note.duration / 1000);
 }
 
+/*
+
+*/
 void StopTimer()
 {
     timer_stop(TIMER_USER);
 }
 /*
-  PlayNote()
-  allow to make different waveforms with '-' and '_'
+    PlayNote()
+    allow to make different waveforms with '-' and '_'
 */
 void PlayNote()
 {
     static int x = 0;
 
-    PutPinState(wave_signal[x]=='-');
+    PutPinState(note.wave_signal[x]=='-');
     x = x + 1;
-    if(!(wave_signal[x])) x = 0;
+    if(!(note.wave_signal[x])) x = 0;
 }
 
 /*
-  PutPinState()
-  put the pin at the level wanted
+    PutPinState()
+    put the pin at the level wanted
 
-  SH4 :
-    state 0 : xxxx.01xx
-    state 1 : xxxx.10xx
-  SH3 :
-    state 0 : xxxx.xxx0
-    state 1 : xxxx.xxx1
+    SH4 :
+        state 0 : xxxx.01xx
+        state 1 : xxxx.10xx
+    SH3 :
+        state 0 : xxxx.xxx0
+        state 1 : xxxx.xxx1
 */
 void PutPinState(char level)
 {
@@ -93,9 +100,9 @@ void PutPinState(char level)
 
 
 /*
-  InitPorts();
-  Ports initialisation
-  Open all need ports to use SwitchPinState()
+    InitPorts();
+    Ports initialisation
+    Open all need ports to use SwitchPinState()
 */
 void InitPorts()
 {
@@ -145,3 +152,14 @@ void InitPorts()
 */
     }
 }
+
+/*
+    Strings functions
+*/
+
+static int strlen(char *str)
+{
+    int i = 0;
+    while(*str++) i++;
+    return i;
+}