From b7a73ecab0b7cf22d9d322e60cac067662ed3465 Mon Sep 17 00:00:00 2001
From: Jonas Gunz <jonas.gunz@googlemail.com>
Date: Thu, 6 Nov 2014 19:53:09 +0100
Subject: Added explaining comments to code

---
 .gitattributes     |   1 +
 .gitignore         |  31 ++++++++++++++++++++++++++++++-
 Tacho_screen.atsuo | Bin 2560 -> 2560 bytes
 Tacho_screen.c     |  43 +++++++++++++++++++++++--------------------
 4 files changed, 54 insertions(+), 21 deletions(-)

diff --git a/.gitattributes b/.gitattributes
index 157cc39..2dd9c86 100644
--- a/.gitattributes
+++ b/.gitattributes
@@ -9,6 +9,7 @@
 *.fsproj merge=union
 *.dbproj merge=union
 *.cproj  merge=union
+*.c	 diff=c
 
 
 
diff --git a/.gitignore b/.gitignore
index 714a294..5f1e7e2 100644
--- a/.gitignore
+++ b/.gitignore
@@ -1,3 +1,4 @@
+@@ -1,227 +1,26 @@
 #################
 ## Eclipse
 #################
@@ -224,4 +225,32 @@ pip-log.txt
 .lss    
 .map    
 .o      
-.srec   
\ No newline at end of file
+.srec   
+ No newline at end of file
+# Auto detect text files and perform LF normalization
+* text=auto
+
+# Custom for Visual Studio
+*.cs     diff=csharp
+*.sln    merge=union
+*.csproj merge=union
+*.vbproj merge=union
+*.fsproj merge=union
+*.dbproj merge=union
+*.cproj  merge=union
+*.c	 diff=c
+
+
+
+# Standard to msysgit
+*.doc	 diff=astextplain
+*.DOC	 diff=astextplain
+*.docx diff=astextplain
+*.DOCX diff=astextplain
+*.dot  diff=astextplain
+*.DOT  diff=astextplain
+*.pdf  diff=astextplain
+*.PDF	 diff=astextplain
+*.rtf	 diff=astextplain
+*.RTF	 diff=astextplain
+
diff --git a/Tacho_screen.atsuo b/Tacho_screen.atsuo
index c58da35..1fd7620 100644
Binary files a/Tacho_screen.atsuo and b/Tacho_screen.atsuo differ
diff --git a/Tacho_screen.c b/Tacho_screen.c
index 9b5a138..ea7cf55 100644
--- a/Tacho_screen.c
+++ b/Tacho_screen.c
@@ -8,10 +8,10 @@
 #include <util/delay.h>
 #include <avr/interrupt.h>
 
-#define _PRIM PORTC
-#define _SEC  PORTD
+#define _PRIM PORTC //Right digit
+#define _SEC  PORTD //Left digit
 
-#define _WHEEL_SIZE 207
+#define _WHEEL_SIZE 207 //In cm
 
 //Define characters (negative)
 #define _C1 0b10101111
@@ -27,25 +27,25 @@
 #define _C_ 0b11111101
 #define _CCLEAR 255
  
-uint32_t cntr; 
-unsigned int speed;
+uint32_t cntr; //counter for Timer
+unsigned int speed; //global var to save the calculated speed in
  
-ISR(TIMER0_OVF_vect)
+ISR(TIMER0_OVF_vect) //ISR for TIMER0 overflow
 {
 	cntr++;
 }
 
 inline void calcSpeed(void)
 {
-	float tmrSpeed = F_CPU / 256;
-	float tmrTime  = 1 / tmrSpeed;
-	float comTime  = tmrTime * cntr;
+	float tmrSpeed = F_CPU / 256; //The timer overflow speed in Hz
+	float tmrTime  = 1 / tmrSpeed; //The timer overflow speed in s
+	float comTime  = tmrTime * cntr; //calculate the total time
 	
-	float mps      = (_WHEEL_SIZE / 100) / comTime;
+	float mps      = (_WHEEL_SIZE / 100) / comTime; //Convert wheelsize to m and derive by the complete time
 	
-	float kmph     = mps * 3.6;
+	float kmph     = mps * 3.6; //km/h = m/s * 3.6
 	
-	speed = (int)kmph;
+	speed = (int)kmph; //cast to int and write into global var speed
 }//calcSpeed()
 
 inline void render(int _screen)
@@ -55,7 +55,10 @@ inline void render(int _screen)
 	int i1, i2;
 	
 	itoa(_screen, cNr, 10); //convert int to string for rendering
-	
+	/*
+	* If _screen is smaller than 10, the cNr contains 1xxxxxxxxxx, but if it is bigger than 10 it looks like this: 10xxxxxxxxxx
+	* So I have to change the digits
+	*/
 	if(_screen < 10)
 	{
 		i1 = 0;
@@ -159,24 +162,24 @@ int main(void)
 	TCCR0 = (1 << CS00); // Prescaler 1
 	TIMSK = (1<<TOIE0); //Enable Overflowinterrupt
 	
-	cntr = 0; //counter for Timer
-	DDRC = DDRD = 255; // Output for scrren pins
+	cntr = 0; //init counter for Timer
+	DDRC = DDRD = 255; // Output for screen pins
 	DDRB |= (1<<PB2);
 	DDRB &= ~(1<<PB1);
 	
-	sei();
+	sei(); //enable interrupts
 	
-	render(0);
+	render(0); //init the display
 	
     while(1)//main loop
 	{	
-		while(PINB & (1 << PB1) && cntr < 30000){} // wait for reed
+		while(PINB & (1 << PB1) && cntr < 30000){} // wait for reedcontact on PB1
 		TCCR0 = ~(1 << CS00); //disable counter
 		cli(); //disable interrupts
 		calcSpeed();
 		//reset all variables
-		cntr = 0;
-		TCNT0 = 0;
+		cntr = 0; //Reset counter	
+		TCNT0 = 0; //Reset Timer
 		sei();//enable interrupts
 		TCCR0 = (1 << CS00); //enable counter
 		
-- 
cgit v1.2.3