// ******************************************************************************************* //
// Include file for PIC24FJ64GA002 microcontroller. This include file defines
// MACROS for special function registers (SFR) and control bits within those
// registers.

#include "p24fj64ga002.h"
#include <stdio.h>

// ******************************************************************************************* //
// Configuration bits for CONFIG1 settings. 
//
// Make sure "Configuration Bits set in code." option is checked in MPLAB.
// This option can be set by selecting "Configuration Bits..." under the Configure
// menu in MPLAB.
//
// These settings are appropriate for debugging the PIC microcontroller. If you need to 
// program the PIC for standalone operation, change the COE_ON option to COE_OFF.

_CONFIG1( JTAGEN_OFF & GCP_OFF & GWRP_OFF & 
		 BKBUG_ON & COE_ON & ICS_PGx1 & 
		 FWDTEN_OFF & WINDIS_OFF & FWPSA_PR128 & WDTPS_PS32768 )

// ******************************************************************************************* //
// Configuration bits for CONFIG2 settings.
// Make sure "Configuration Bits set in code." option is checked in MPLAB. 
// This option can be set by selecting "Configuration Bits..." under the Configure
// menu in MPLAB.

_CONFIG2( IESO_OFF & SOSCSEL_SOSC & WUTSEL_LEG & FNOSC_PRIPLL & FCKSM_CSDCMD & OSCIOFNC_OFF &
		 IOL1WAY_OFF & I2C1SEL_PRI & POSCMOD_XT )

// ******************************************************************************************* //
// Defines to simply UART's baud rate generator (BRG) regiser
// given the osicllator freqeuncy and PLLMODE.

#define XTFREQ    7372800         	  // On-board Crystal frequency
#define PLLMODE   4               	  // On-chip PLL setting (Fosc)
#define FCY       (XTFREQ*PLLMODE)/2  // Instruction Cycle Frequency (Fosc/2)

// Baud rate calculation for UART1 (BRGH=0)
#define BAUDRATE  115200       
#define BRGVAL    ((FCY/BAUDRATE)/16)-1 

// ******************************************************************************************* //

volatile unsigned char sampleADC;

// ******************************************************************************************* //

int main(void)
{	
	short int rawADCValue;	
	
	// ******************************************************************************* //
	// UART1 is connected to host PC
	// ******************************************************************************* //
	
	// RPINR18 is a regsiter for selectable input mapping (see Table 10-2) for 
	// for UART1. U1RXR is 8 bit value used to specifiy connection to which
	// RP pin. RP9 is used for this configuration. Physical Pin 18.
	RPINR18bits.U1RXR = 9;	
	
	// RPOR4 is a register for selctable ouput mapping for
	// pins RP9 and RP8. The register for RP8 is assigned to 3 to connect 
	// the U1TX output for UART1 (see table 10-3). Physical Pin 17.
	RPOR4bits.RP8R = 3;		
	
	// Set UART1's baud rate generator register (U1BRG) to the value calculated above.
	U1BRG  = BRGVAL;
	
	// Set UART1's mode register to 8-bit data, no parity, 1 stop bit, enabled.
	//     UARTEN        = 1     (enable UART)
	//     PDSEL1:PDSEL0 = 00    (8-bit data, no parity)
	//     STSEL         = 0     (1 stop bit)
	U1MODE = 0x8000; 		
	
	// Set UART2's status and control register
	//     UTXISEL1:UTXISEL0 = 00    (U1TXIF set when character 
	//                                written to trasmit buffer)
	//     UTXEN             = 1     (trasnmit enabled)
	//     URXISEL1:URXISEL0 = 01    (U1RXIF set when any character 
	//                                is received in receive buffer)
	//     RIDLE             = 0     (Reciver is active)
	U1STA  = 0x0440; 		// Reset status register and enable TX & RX
	
	// ******************************************************************************* //
	
    // Set Timer1's Prescaler to 1:256
	T1CONbits.TCKPS = 3;
	
	// Set Timer 1's period value regsiter to value for 250ms. Please note 
	// T1CON's register settings below (internal Fosc/2 and 1:256 prescalar).
	// 
	//    Fosc     = XTFREQ * PLLMODE
	//             = 7372800 * 4
	//             = 29491200
	// 
	//    Fosc/2   = 29491200 / 2
	//             = 14745600
	//
	//    Timer 1 Freq = (Fosc/2) / Prescaler
	//                 = 14745600 / 256
	//                 = 57600
	//
	//    PR1 = 250 ms / (1 / (T1 Freq)) - 1
	//        = 250e-3 / (1 / 57600) - 1
	//        = 250e-3 * 57600 - 1
	//        = 14400 - 1 
	PR1 = 14399;
	
	// Clear Timer value (i.e. current tiemr value) to 0
	TMR1 = 0;				
	
	// Clear Timer 1 interrupt flag. This allows us to detect the 
	// first interupt.
	IFS0bits.T1IF = 0;		
	
	// Enable the interrupt for Timer 1
	IEC0bits.T1IE = 1;
	
 	// Start Timer 1
	T1CONbits.TON = 1;
	
	// ******************************************************************************* //
	
	// TODO: Set AN5 as Analog inputs.
	
	// TODO: Configure ADC MUXA channel for AN5 input and MUXB channel for AN4 input
	
	// TODO: Internal counter used to stop sampling and start conversion
	
	// TODO: Use AVdd+ (pin 28) and AVss- (pin 27) as reference voltage signals.
	
	// TODO: Use system clock to determine auto sample time and converson time.
	
	// TODO: Setup sample time to 1 ADC cycle (minimum possible sample time) and
	// conversion time to 1 ADC cycle (minimum possible conversion time)
	
	// Turn ADC On
	AD1CON1bits.ADON = 1; 
	
	// ******************************************************************************* //
	
	while(1)
	{
		if( sampleADC == 1 ) {
			sampleADC = 0;
			
			// TODO: Clear AD1IF so we can detect end of ADC sampling/conversion.
			// TODO: Start sampling/conversion by setting ASAM to 1.
			// TODO: Wait for sampling/conversion to complete by checking AD1IF.
			// TODO: Reset ASAM to 0 so we can sample again.
			// TODO: Read 10-bit ADC valie from ADC1BUF0 regiser.
			
			
			// Let's see what the value is.
			printf("%i (%04x)\n\r", rawADCValue, rawADCValue);
		}	
	}
	
	return 0;
}

// ******************************************************************************************* //

void _ISR _T1Interrupt(void)
{
	IFS0bits.T1IF = 0;		
	sampleADC = 1;	
}

// ******************************************************************************************* //