From c277b2d85f3915133d76b9bfba3310b93d5602ed Mon Sep 17 00:00:00 2001
From: mandlm <mandlm@molez.net>
Date: Sun, 14 Feb 2016 19:02:59 +0100
Subject: [PATCH] Interrupt-based measuring

---
 UltraSonic/dist/main.cpp | 96 ++++++++++++++++++++++------------------
 1 file changed, 52 insertions(+), 44 deletions(-)

diff --git a/UltraSonic/dist/main.cpp b/UltraSonic/dist/main.cpp
index 15f8c54..d964463 100644
--- a/UltraSonic/dist/main.cpp
+++ b/UltraSonic/dist/main.cpp
@@ -1,12 +1,37 @@
 #include "environment.h"
 
 #include <avr/io.h>
+#include <avr/interrupt.h>
 #include <util/delay.h>
 
 #include <stdio.h>
 
 #include "ShiftRegister.h"
 #include "KS0066.h"
+#include "Pin.h"
+
+volatile bool measuring = false;
+volatile int16_t dist = 0.0;
+
+ISR(INT1_vect)
+{
+	if (PIND & (1 << PD3))
+	{
+		measuring = true;
+		TCNT1 = 0;
+	}
+	else if (measuring == true)
+	{
+		dist = TCNT1 * 0.09175;
+
+		measuring = false;
+	}
+}
+
+ISR(TIMER1_COMPA_vect)
+{
+	measuring = false;
+}
 
 int main(void)
 {
@@ -15,65 +40,48 @@ int main(void)
 	ShiftRegister shiftRegister(&PORTC, PC4, &PORTC, PC2, &PORTC, PC3);
 	KS0066 lcd(shiftRegister);
 
+	// led ports to output
+	DDRD |= (1 << PD6) | (1 << PD5);
+
 	lcd.set("Ultra-sonic");
 
-	DDRB |= (1 << PB0);		// PB0 trigger output
-	DDRB &= ~(1 << PB1);	// PB1 pulse input
+	DDRD |= (1 << PD4);		// PD4 trigger output
+	DDRD &= ~(1 << PD3);	// PD3 pulse input
 
 	// Timer 1, normal mode
 	TCCR1A = 0;
+	TCCR1B |= (1 << WGM12);		// CTC
 
 	// Timer 1, clk/64 prescaler
 	TCCR1B |= (1 << CS10) | (1 << CS11);
 
-	_delay_ms(2000);
+	// Timer 1, output compare interrupt 1A
+	TIMSK |= (1 << OCIE1A);
+
+	// Timer 1, compare value
+	OCR1A = 30000;
+
+	_delay_ms(500);
 	lcd.clear();
 
+	// INT1, on change
+	GICR |= (1 << INT1);
+	MCUCR |= (1 << ISC10);
+
+	sei();
+
 	while (true)
 	{
-		uint8_t errorNum = 0;
+		PORTD |= (1 << PD4);
+		_delay_ms(25);
+		PORTD &= ~(1 << PD4);
+		_delay_ms(25);
 
-		PORTB |= (1 << PB0);
-		_delay_us(15);
-		PORTB &= ~(1 << PB0);
-		_delay_us(20);
+		char buffer[16];
+		sprintf(buffer, "%3i cm", dist);
+		lcd.set(buffer);
 
-		TCNT1 = 0;
-		while ((PINB & (1 << PB1)) == 0 && errorNum == 0)
-		{
-			if (TCNT1 > 60000)
-			{
-				errorNum = 1;
-				lcd.set("Timeout");
-			}
-		}
-
-		if (errorNum == 0)
-		{
-			TCNT1 = 0;
-
-			while ((PINB & (1 << PB1)) != 0 && errorNum == 0)
-			{
-				if (TCNT1 > 60000)
-				{
-					errorNum = 2;
-					lcd.set("No object");
-				}
-			}
-
-			if (errorNum == 0)
-			{
-				uint16_t ticks = TCNT1;
-
-				uint16_t cm = (ticks * 1.835) / 20.0;
-
-				char buffer[16];
-				sprintf(buffer, "%3i cm", cm);
-				lcd.set(buffer);
-			}
-		}
-
-		_delay_ms(200);
+		_delay_ms(250);
 	}
 }