/*
 * geigerzaehler.c
 *
 * Created			:	28.02.2019 09:07:22
 * Author			:	John Ditgens, Alexander Brandscheidt
 * Git-Repository	:	https://gitea.Railduction.eu/JohnD/Geigerzaehler.git
 *
 * MController		:	AtMega328P
 * Board			:	Arduino Nano
 */ 
#define F_CPU 16000000UL 				// Clock speed: 16 MHz	- Speed from onboard oscillator

// Imports
#include <avr/io.h>
#include <avr/interrupt.h>
#include <stdint.h>

// Global variable declaration
uint16_t boost_frequency = 2000;		// 2kHz frequency
uint16_t signalOutput_time = 200;		// 200ms

uint8_t boost_highVoltage_nextHigh	=	1;
uint16_t boost_highVoltage_nextTick	=	0;

uint8_t signalOutput_nextHigh	=	1;
uint16_t signalOutput_nextTick	=	0;

uint8_t timer1_prescaler = 256;

int main()
{
	// Inputs
    DDRD &= (0 << PORTD2);					// Activate input PD2
    DDRD &= (0 << PORTD3);					// Activate input PD3						
	//PORTD |= (1 << PORTD2);					// Enable pull-up-resistor D2
	//PORTD |= (1 << PORTD3);					// Enable pull-up-resistor D3
	// Todo [CRITICAL]: External pull-down resistors	10kOhm
	
	// Outputs
	DDRD |= (1 << PORTD4);
	DDRD |= (1 << PORTD5);
	DDRD |= (1 << PORTD6);
	
	// Interrupt for INT0	Pin-D2	High-voltage check
    EICRA |= (0 << ISC01)|(1 << ISC00); // On at any edge		[Code: 01]
    EIMSK |= (1 << INT0);				// Activate Interrupt INT0
    
	// Interrupt for INT1	Pin-D3	Counter-click
    EICRA |= (1 << ISC11)|(1 << ISC10);	// On rising edge		[Code: 11]
    EIMSK |= (1 <<INT1);				// Activate Interrupt INT1
	
	// Init timer1
	timer1_init();
	
    sei();		// Activate global interrupts
	
	// Endless loop
    while (1) 
    {
		/*
		 * HighVoltage boosting
		 */
		if(boost_highVoltage_nextTick > 0 && TCNT1 >= boost_highVoltage_nextTick)	// If we are on or after the tick it should be executed
		{
			// Set pin according to next exec
			if(boost_highVoltage_nextHigh == 1)		
			{
				// Set it high
				PORTD |= (1 << PORTD4);
				boost_highVoltage_nextHigh = 0;	// Next is low
			}
			else  								
			{
				// Set it low
				PORTD |= (0 << PORTD4);
				boost_highVoltage_nextHigh = 1;	// Next is high
			}
				
			// Calculate when next high/low should be set
			boost_highVoltage_nextTick = TCNT1 + F_CPU/timer1_prescaler * 1/(boost_frequency/2);		// Half of time it should be high/low
			if(boost_highVoltage_nextTick == 0) boost_highVoltage_nextTick++;		// If its 0, it stops, we dont want that
		}
		
		/*
		 * Signal output
		 */
		if(signalOutput_nextTick > 0 && TCNT1 >= signalOutput_nextTick)	// If we are on or after the tick it should be executed
		{
			// Set pin according to next exec
			if(signalOutput_nextHigh == 1)		// Set it high
			{
				PORTD |= (1 << PORTD5);
				PORTD |= (1 << PORTD6);
				signalOutput_nextHigh = 0;	// Next is low
			}
			else  								// Set it low
			{
				PORTD |= (0 << PORTD5);
				PORTD |= (0 << PORTD6);
				signalOutput_nextHigh = 1;	// Next is high
				
				signalOutput_nextTick = 0;	// Disable signalOutput
			}
			
			// When the signal should stop
			signalOutput_nextTick = TCNT1 + F_CPU/timer1_prescaler * signalOutput_time/1000; 		// nextTick is in signalOutput_time in ms
			if(signalOutput_nextTick == 0) signalOutput_nextTick++;		// If its 0, it stops, we dont want that
		}
    }
}

/* 
 * Init timer1 (16-bit) in "normal mode"
 */
void timer1_init()
{
	// set up timer with speed: cpu-clock / prescaler
	switch(timer1_prescaler){		// [CS12	CS11	CS10]
		default:
		case 1:
			TCCR1B |= (1 << CS10);	// [0		0		1	]
			break;
		
		case 8:
			TCCR1B |= (1 << CS11);	// [0		1		0	]
			break;
		
		case 64:
			TCCR1B |= (1 << CS10);	// [0		1		1	]
			TCCR1B |= (1 << CS11);
			break;
		
		case 256:
			TCCR1B |= (1 << CS12);	// [1		0		0	]
			break;
			
		case 1024:
			TCCR1B |= (1 << CS10);	// [1		0		1	]
			TCCR1B |= (1 << CS12);
			break;
	}
	
	// initialize counter
	TCNT1 = 0;
}


/*
 * Interrupt-handler
 * ISR - Interrupt service routine
 */
// Address: 0x001	INT0	-	On any edge		[Code: 01]
// Handles:	Over/Below working voltage
ISR(INT0_vect)
{
	if(!(PIND & (1 << PORTD2)))	// Falling edge
	{	
		// Below ~400V, activate booster
		boost_highVoltage_nextTick = 1;	//  Run as soon as possible
	}
	else					// Rising edge
	{
		// Reached ~400V, deactivate booster
		boost_highVoltage_nextTick = 0;
		
		// reset state
		PORTD |= (0 << PORTD4);			// pin on low
		boost_highVoltage_nextHigh = 1;	// next is high
	}
	
	reti();		// Exit interrupt-handler
}

// Address: 0x002	INT1	-	On rising edge	[Code: 11]
// Handles:	Counter tube "tick"
ISR(INT1_vect)
{
	// Tick detected, signalOutput
	signalOutput_nextTick = 1;	//  Run as soon as possible
	
	reti();		// Exit interrupt-handler
}