diff --git a/src/Sound4Calc.c b/src/Sound4Calc.c
index 251fc2f..4d9f212 100755
--- a/src/Sound4Calc.c
+++ b/src/Sound4Calc.c
@@ -6,8 +6,6 @@
 #include <keyboard.h>
 #include <mpu.h>
 
-#include "string.h"
-
 
 //#define DEBUG
 
@@ -31,8 +29,7 @@ unsigned char range = 0;
 
 void lect440()
 {
-
-    if(bincod[range]- '0')
+    if(bincod[range+1] != bincod[range])
     {
         if(isSH3())
         {
@@ -50,7 +47,7 @@ void lect440()
 int main(void)
 {
     unsigned int key=0;
-    unsigned char range = 1;
+
     int freq = 220;
 
     //unsigned int i=0;