diff --git a/main.c b/main.c
index 363b670..5f0f63a 100644
--- a/main.c
+++ b/main.c
@@ -239,14 +239,16 @@ static void vfd_digit(uint8_t nb, char c)
 	if (false) { // add the comma (not encoded)
 		vfd_data[1] |= (1<<(16));
 	}
-		
-	if (((c&0x7f)<' ') || ((c&0x7f)>' '+LENGTH(ascii_7segments)-1)) { // unknown ASCII character
-		vfd_data[1] = 0; // add empty segments to memory
-	} else {
-		vfd_data[1] |= (ascii_7segments[c-' ']<<(17)); // add encoded segments to memory
-	}	
 	
-	vfd_data[2] = 0;
+	c &= 0x7f; // only take the ASCII part
+	if (c>=' ') { // only take printable characters
+		uint8_t i = c-' '; // get index for character
+		if (i<LENGTH(ascii_7segments)) {
+			vfd_data[1] |= (ascii_7segments[i]<<(17)); // add encoded segments to memory
+		}
+	}
+	
+	vfd_data[2] = 0; // last part is not used
 }
 
 /* font for the 5x7 dot matrix display
@@ -374,9 +376,9 @@ static void vfd_matrix(uint8_t nb, char c)
 		vfd_data[1] = 0;
 	}
 	
-	if (c<0x80) {
-		uint8_t i = c-' ';
-		vfd_data[2] = 0;
+	vfd_data[2] = 0;
+	if ((c<0x80) && (c>=' ')) { // only take printable characters
+		uint8_t i = c-' '; // get index for character
 		if (i<LENGTH(ascii_font5x7)) {
 			vfd_data[1] |= ascii_font5x7[i][0]<<24;
 			vfd_data[2] |= ascii_font5x7[i][1]<<0;
@@ -384,18 +386,14 @@ static void vfd_matrix(uint8_t nb, char c)
 			vfd_data[2] |= ascii_font5x7[i][3]<<16;
 			vfd_data[2] |= ascii_font5x7[i][4]<<24;
 		}
-	} else {
-		uint8_t i = c-0x80;
-		vfd_data[2] = 0;
+	} else if (c>0x7f) { // the non ASCII character are used for pictures
+		uint8_t i = c-0x80; // get index for character
 		if (i<LENGTH(ascii_pict5x7)) {
-			vfd_data[2] = 0;
 			vfd_data[1] |= ascii_pict5x7[i][0]<<24;
 			vfd_data[2] |= ascii_pict5x7[i][1]<<0;
 			vfd_data[2] |= ascii_pict5x7[i][2]<<8;
 			vfd_data[2] |= ascii_pict5x7[i][3]<<16;
 			vfd_data[2] |= ascii_pict5x7[i][4]<<24;
-		} else {
-			vfd_data[2] = 0;
 		}
 	}
 }
@@ -423,9 +421,8 @@ int main(void)
 	uint8_t matrix = 0;
 	char c = ' ';
 	
-	vfd_digit(digit,c);
+	vfd_digit(digit,'0');
 	vfd_shift();
-	digit = (digit+1)%10;
 	// let the fluorescence glow up a bit
 	for (uint32_t i = 0; i < 0x2000; i++) {
 		__asm__("nop");