#include <p18F452.h>
#include <delays.h>
#include <stdio.h>
#include <usart.h>

/* Set up the configuration bits */
#pragma config OSC = HS
#pragma config PWRT = OFF
#pragma config BOR = OFF
#pragma config WDT = OFF
#pragma config LVP = OFF

#define BAUD 9600
#define FOSC 20000000L

#define MIPS 5
#define LOW_PULSE_PERIOD (500L) // in ms
#define HIGH_PULSE_PERIOD (100L) // in ms
#define	LOW_PULSE_COUNT (0xFFFF - (LOW_PULSE_PERIOD*MIPS*1000L)/256L)
#define	HIGH_PULSE_COUNT (0xFFFF - (HIGH_PULSE_PERIOD*MIPS*1000L)/256L)
#define ERROR 1
#define DEVICE_ADDRESS 	0b10010000 // Address(7:1)


static unsigned int T0_pulse_count;
static signed char current_temp;
static signed char assigned_temp;
static char state = 'O'; // off; + -> heat; - -> cold

void interrupt_handler (void);

#pragma code high_vector=0x08
void high_priority_interrupt (void)
{
	_asm GOTO interrupt_handler _endasm
}

#pragma code

void usart_setup(void)
{
	// Set the port direction.
	TRISCbits.TRISC6 = 0;
	TRISCbits.TRISC7 = 1;

	// High baud rate select (TXSTA)
	TXSTAbits.BRGH = 1;

	// compute the divider for speed (see page 161)
	SPBRG = ((int)(FOSC/(16UL * BAUD) -1));

	// Asynchronous mode (TXSTA)
	TXSTAbits.SYNC = 0;

	// 8 bits reception (RCSTA)
	RCSTAbits.RX9 = 0;

	// enable the receiver (RCSTA)
	RCSTAbits.CREN = 1;

	// 8 bits transmission (TXTSA)
	TXSTAbits.TX9 = 0;

	// enable transmission (TXTSA)
	TXSTAbits.TXEN = 1;

	// enable the Serial Port (RCSTA)
	RCSTAbits.SPEN = 1;
}

void io_port_setup(void)
{
	// RE2 for input and RE1 for output;
	TRISE = 0b00000100;

	// RE1 (LED) is on;
	PORTE = 0b00000010;

	// RA0 for input;
	TRISA = 0b00000001;

	// Select AN0 as Anolog and AN6/7 (RE1/2) as digital
	// We are using the internal reference (VDD)
	// PCFG3:0 = 0010
	ADCON1 = 0b00001001;

	// Result is left aligned in ADRESH
	ADCON1bits.ADFM = 0;

	// Conversion clock set to Fosc/32 (ADCS2:0 = 010)
	// Fosc = 20Mhz
	ADCON1bits.ADCS2 = 0;
	ADCON0bits.ADCS1 = 1;
	ADCON0bits.ADCS0 = 0;

 	// We are sampling AN0: CHS2:0 = 000
	// ADCON0 = ((ADCON0 & 0b11100011) | 0b00000000);
	ADCON0bits.CHS2 = 0;
	ADCON0bits.CHS1 = 0;
	ADCON0bits.CHS0 = 0;

	// Powering the module
	ADCON0bits.ADON = 1;

	// Clears A2D interrupt flag
	PIR1bits.ADIF = 0;

	// Allows A2D to trigger an interrupt 
	PIE1bits.ADIE = 1;

	// acquisition delay?

	// Starting the fist conversion
	ADCON0bits.GO = 1;
}

void update_T0_value(unsigned int value)
{
	TMR0H = value >> 8;
	TMR0L = value & 0xFF;
}

void timer0_setup(void)
{
	T0_pulse_count = LOW_PULSE_COUNT;

	// Select low to high transition
	T0CONbits.T0CS = 0;
	
	// Select the pre-scaler
	T0CONbits.PSA = 0;

	// Set the pre-scaler value (T0PS2:0 = 111 -> 256)
	T0CON = ((T0CON & 0b11111000) | 0b00000111);

	// Set TO to be a 16bits timer
	T0CONbits.T08BIT = 0;

	// Load the timer value
	update_T0_value(T0_pulse_count);

	// Clear Timer0 interrupt flag
	INTCONbits.TMR0IF = 0;

	// Set Timer0 to trigger interrupt
	INTCONbits.TMR0IE = 1;

	// Start Timer0
	T0CONbits.TMR0ON = 1;
}

void I2C_setup()
{
	// Disable the SSP module for settings
	SSPCON1bits.SSPEN = 0;

	// Set the SSP as a I2C master SSPM3:0 -> 1000
	SSPCON1 = (SSPCON1 & 0b11110000)|(0b00001000);

	// Set the Baud generator (20MHz/100KHz)/4 - 1 = 49;
	SSPADD = 49;

	// Standard speed mode (no Slew control)
	SSPSTATbits.SMP = 1;

	// set SCK (RC3) and SDI (RC4) as input
	TRISCbits.TRISC3 = 1;
	TRISCbits.TRISC4 = 1;

	SSPCON1bits.WCOL = 0;
	
	// Enable the SSP module
	SSPCON1bits.SSPEN = 1;

	// Set the slave configuration 

	// start event (S)
	SSPCON2bits.SEN = 1;
	while (SSPCON2bits.SEN == 1);

	// Address on the bus;
	SSPBUF = DEVICE_ADDRESS;
	while (SSPSTATbits.R_W == 1);

	// Command word on the bus;
	SSPBUF = 0;
	while (SSPSTATbits.R_W == 1);

	// Stop event (P)
	SSPCON2bits.PEN = 1;
	while (SSPCON2bits.PEN == 1);
}

signed char I2C_temp_read()
{
	unsigned char result = 0;

	// start event (S)
	SSPCON2bits.SEN = 1;
	while (SSPCON2bits.SEN == 1);

	// Address on the bus (READ flag set);
	SSPBUF = DEVICE_ADDRESS | 0b00000001;
	while (SSPSTATbits.R_W == 1);

	// Prepare to received from the bus
	SSPCON2bits.RCEN = 1;

	// Wait until the received is done...
	while (SSPCON2bits.RCEN == 1);
	result = SSPBUF;	

	// NACK to the slave
	SSPCON2bits.ACKDT = 1;
	SSPCON2bits.ACKEN = 1;
	while (SSPCON2bits.ACKEN == 1);

	// Stop event (P)
	SSPCON2bits.PEN = 1;
	while (SSPCON2bits.PEN == 1);
	
	return(result);
}

#pragma interrupt interrupt_handler
void interrupt_handler(void)
{
	if (PIR1bits.ADIF == 1)
	{
		// New A2D result!
		assigned_temp = 20 - ((ADRESH - 128)/8);

		switch (state)
		{
			case 'O':
				if (current_temp > (assigned_temp + ERROR))
				{
					state = '-'; // Switch on the AC
				}
				if (current_temp < (assigned_temp - ERROR))
				{
					state = '+'; // Switch on the Heat
				}
			break;
			case '+':
				if (current_temp >= assigned_temp)
				{
					state = 'O';
				}
			break;
			case '-':
				if (current_temp <= assigned_temp)
				{
					state = 'O';
				}
			break;
			default:
			break;
		}
	
		printf("Assigned: %d; Current: %d", assigned_temp, current_temp); 
		switch (state)
		{
			case 'O':
				printf(" OFF    \r"); 
			break;
			case '+':
				printf(" HEAT ON\r"); 
			break;
			case '-':
				printf(" AC ON  \r"); 
			break;
			default:
			break;
		}
	

		// Clear the interrupt flag
		PIR1bits.ADIF = 0;
	}

	if (INTCONbits.TMR0IF == 1)
	{
		// Timer expired
		// Load the new value
		update_T0_value(T0_pulse_count);

		current_temp = I2C_temp_read();
		
		// Clear the interrupt flag
		INTCONbits.TMR0IF = 0;

		// Start a new conversion
		ADCON0bits.GO = 1;
	}
}

void main( void)
{
	char input;

	// setup the ports
	io_port_setup();

	// setup the USART
	usart_setup();

	// setup timer_0;
	timer0_setup();

	I2C_setup();

	printf("\n\r");
	printf("\n\r");

	// Not Interupt Priority
	RCONbits.IPEN = 0;

	// Allows for Peripheral interrupts
	INTCONbits.PEIE = 1;
  
	// Interrupts are on
	INTCONbits.GIE = 1;

	// Loop forever
	while (1);
}