changed debouncing again, clear button changed every timer overflow

Author: atar-axis

main.c

@@ -24,23 +24,23 @@ volatile int avr_online_state;
 
 void timer0_ISR (void) interrupt 1
 {
-	static float avg_button = 100;
-	static float avg_avr_online = 100;
+	static float avg_button = 10;
+	static float avg_avr_online = 10;
 
 	int new_button_state;
 	int new_avr_online_state;
 
 	// Increment Counter to shorten overflow time
-	TH0 = (65536 - 1000)/256;     // TODO: Calculation?! Old: 1ms = 1000MZ, davon das High-Byte in TH0
-	TL0 = (65536 - 1000)%256;     // das Low-Byte in TL0
+	TH0 = (65536 - 1000) / 256; // TODO: Calculation?! Old: 1ms = 1000MZ, davon das High-Byte in TH0
+	TL0 = (65536 - 1000) % 256; // das Low-Byte in TL0
 
-	// Button entprellen
-
-
-	avg_button     = (avg_button * 9     + I_BUTTON * 100)     / 10;
+	// Button debouncing using exponential moving average
+	// ? avg = alpha * avg + (1 - alpha) * input, alpha < 1
+	avg_button = 0.9 * avg_button + 0.1 * (I_BUTTON * 10);
+	// avg_button     = (avg_button * 9     + I_BUTTON * 100)     / 10;
 	avg_avr_online = (avg_avr_online * 9 + I_AVR_ONLINE * 100) / 10;
 
-	if (avg_button > 50) {
+	if (avg_button > 5) {
 		new_button_state = HIGH;
 	} else {
 		new_button_state = LOW;
@@ -52,34 +52,29 @@ void timer0_ISR (void) interrupt 1
 		new_avr_online_state = LOW;
 	}
 
-
 	if (new_button_state != button_state) {
 		button_state = new_button_state;
 		button_changed = 1;
+	} else {
+		button_changed = 0;
 	}
 
 	if (new_avr_online_state != avr_online_state) {
 		avr_online_state = new_avr_online_state;
 	}
-	
 }
 
 
 void setup()
 {
-	// P33 (I_AVR_ONLINE) to Input only (HiZ)
-	//P3M0 &= ~(0 << 3);
-	//P3M1 |= 1 << 3;
+	// Keep P33 (I_AVR_ONLINE) and P34 (I_BUTTON) as Quasi-Bidirectional
+	// since we need the internal PullUps
 
-	// P34 (I_BUTTON) to Input only (HiZ)
-	//P3M0 &= ~(0 << 4);
-	//P3M1 |= 1 << 4;
-
-	// P35 (O_BOOST) to PushPull Output
+	// P35 (O_BOOST): PushPull Output
 	P3M0 |= 1 << 5;
 	P3M1 &= ~(0 << 5);
 
-	// P32 (O_AVR_BUTTON) to PushPull Output
+	// P32 (O_AVR_BUTTON): PushPull Output
 	P3M0 |= 1 << 2;
 	P3M1 &= ~(0 << 2);
 
@@ -88,19 +83,18 @@ void setup()
 	button_changed = 0;
 	button_state = HIGH;
 	avr_online_state = LOW;
-	
+
 	// Init I/O's
 	O_AVR_BUTTON = HIGH;
 	O_BOOST = LOW;
-	I_BUTTON = 1; // quasi-bidirectional => pullups!
-	I_AVR_ONLINE = 1; // quasi-bidirectional => pullups!
+	I_BUTTON = 1;     // set to weak high => pullups!
+	I_AVR_ONLINE = 1; // set to weak high => pullups!
 
 	// Timers
-	TMOD = (TMOD & 0xF0) | 0x01;  // Set T/C0 Mode 1, 16Bit, No Auto Reload
+	TMOD = (TMOD & 0xF0) | 0x01;  // Set T/C0 Mode 1, 16Bit, Manual Reload
 	ET0 = 1;                      // Enable Timer 0 Interrupts
 	TR0 = 1;                      // Start Timer 0 Running
 	EA = 1;                       // Global Interrupt Enable
-
 }
 
 void delay(int ms)
@@ -128,12 +122,11 @@ void main()
 	{
 		switch (state) {
 		case SLEEP:
-			
 			// TODO: POWER SAVING OPTIONS
 			// deactivate timer, enable interrupt2, ...
 
 			if (button_changed && button_state == LOW) {
-				button_changed = 0;
+				//button_changed = 0;
 				O_AVR_BUTTON = LOW;
 				delay(1); // otherwise the fw hangs up
 				O_BOOST = HIGH;
@@ -145,7 +138,7 @@ void main()
 
 		case BOOT:
 			O_AVR_BUTTON = button_state;
-		
+
 			if (avr_online_state == HIGH)
 				state = ONLINE;
 
@@ -159,7 +152,7 @@ void main()
 			if (avr_online_state == LOW) {
 				O_BOOST = LOW;
 				state = SLEEP;
-				button_changed = 0; // clear the button event, otherwise you cannot shut down
+				//button_changed = 0; // clear the button event, otherwise you cannot shut down
 			}
 			break;