// ******************************************************************************************* //
// 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>
#include "lcd.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 BAUDRATE1         115200       
#define BRGVAL1          ((FCY/BAUDRATE1)/16)-1 

// Baud rate calculation for UART2 (BRGH=1)
#define BAUDRATE2         4800       
#define BRGVAL2          ((FCY/BAUDRATE2)/16)-1 

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

#define CMD_LENGTH 6
#define MSG_BUFFER_LENGTH 256

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

const char* GPRMCCommandString = "$GPRMC";

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

volatile char cmdBuffer[CMD_LENGTH];
volatile char msgBuffer[MSG_BUFFER_LENGTH+1];
volatile unsigned msgIndex;
volatile unsigned msgUpdate;

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

int main(void)
{
	// ******************************************************************************* //
	// UART1 is used to re-transmit data received from GPS module 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 (see Regsiter 1019) 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  = BRGVAL1;
	
	// 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
	
	// ******************************************************************************* //
	// UART2 used to collect receive data from GPS Module
	// PolStart PMB-GPS Module uses a 4800 buad rate, assuming 8-bits, 1 stop bit.
	//
	// NOTE: The TX output for UART2 is not connected.
	// ******************************************************************************* //
	
	// RPINR19 is a regsiter for selectable input mapping (see Table 10-2) for 
	// for UART2. U2RXR is 8 bit value used to specifiy connection to which
	// RP pin. RP11 is used for this configuration. Physical Pin 22.
	// Pin 22 is the IO10 connection on the 16-bit 28-pin Starter Board
	RPINR19bits.U2RXR = 11;	
	
	// Set UART2's baud rate generator register (U2BRG) to the value calculated above.
	U2BRG  = BRGVAL2;
	
	// Set UART2'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)
	U2MODE = 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)
	U2STA  = 0x0440; 		// Reset status register and enable TX & RX
	
	// Clear the UART2's RX interrupt flag. Althouhg we are not using a ISR for 
	// the UART receive, the UART RX interrupt flag can be used to deermine if 
	// we have recived a character from he UART. 
	IFS1bits.U2RXIF = 0;
	
	// Enable the UART 2 RX interrupt 
	IEC1bits.U2RXIE = 1;
	
	msgUpdate = 0;
	msgIndex = 0;
	
	while(1)
	{
		if( msgUpdate == 1 ) {			
			printf("%s\n\r", msgBuffer);
			msgUpdate = 0;
		}
	}
	return 0;
}

// ******************************************************************************************* //
// Defines an interrupt service routine that will execute whenever Timer 1's
// count reaches the specfied period value defined within the PR1 register.
// 
//     _ISR and _ISRFAST are macros for specifying interrupts that 
//     automatically inserts the proper interrupt into the interrupt vector 
//     table
//
// The functionality defined in an interrupt should be a minimal as possible
// to ensure additional interrupts can be processed. 
void _ISR _U2RXInterrupt(void)
{
	char receivedChar;
	
	IFS1bits.U2RXIF = 0;
	receivedChar = U2RXREG;
	
	if( receivedChar == '\n' ) {
		msgBuffer[msgIndex] = 0;
		msgUpdate = 1;
		msgIndex = 0;
	}
	else {
		if( msgIndex < (MSG_BUFFER_LENGTH-1) ) {
			msgBuffer[msgIndex++] = receivedChar;
		}
	}
}

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