/*
 * File: Main.c
 * Author:
 *
 * Created on June 13, 2019, 2:22 PM
 */

#define _XTAL_FREQ 32000000

// PIC16F18875 Configuration Bit Settings

// 'C' source line config statements

// CONFIG1
#pragma config FEXTOSC = OFF // External Oscillator mode selection bits (EC above 8MHz; PFM set to high power)
#pragma config RSTOSC = HFINT32 // Power-up default value for COSC bits (EXTOSC operating per FEXTOSC bits)
#pragma config CLKOUTEN = OFF // Clock Out Enable bit (CLKOUT function is disabled; i/o or oscillator function on OSC2)
#pragma config CSWEN = ON // Clock Switch Enable bit (Writing to NOSC and NDIV is allowed)
#pragma config FCMEN = ON // Fail-Safe Clock Monitor Enable bit (FSCM timer enabled)

// CONFIG2
#pragma config MCLRE = ON // Master Clear Enable bit (MCLR pin is Master Clear function)
#pragma config PWRTE = OFF // Power-up Timer Enable bit (PWRT disabled)
#pragma config LPBOREN = OFF // Low-Power BOR enable bit (ULPBOR disabled)
#pragma config BOREN = OFF // Brown-out reset enable bits (Brown-out Reset Enabled, SBOREN bit is ignored)
#pragma config BORV = LO // Brown-out Reset Voltage Selection (Brown-out Reset Voltage (VBOR) set to 1.9V on LF, and 2.45V on F Devices)
#pragma config ZCD = OFF // Zero-cross detect disable (Zero-cross detect circuit is disabled at POR.)
#pragma config PPS1WAY = ON // Peripheral Pin Select one-way control (The PPSLOCK bit can be cleared and set only once in software)
#pragma config STVREN = ON // Stack Overflow/Underflow Reset Enable bit (Stack Overflow or Underflow will cause a reset)

// CONFIG3
#pragma config WDTCPS = WDTCPS_31// WDT Period Select bits (Divider ratio 1:65536; software control of WDTPS)
#pragma config WDTE = OFF // WDT operating mode (WDT enabled regardless of sleep; SWDTEN ignored)
#pragma config WDTCWS = WDTCWS_7 // WDT Window Select bits (window always open (100%); software control; keyed access not required)
#pragma config WDTCCS = SC // WDT input clock selector (Software Control)

// CONFIG4
#pragma config WRT = OFF // UserNVM self-write protection bits (Write protection off)
#pragma config SCANE = available // Scanner Enable bit (Scanner module is available for use)
#pragma config LVP = OFF // Low Voltage Programming Enable bit (Low Voltage programming enabled. MCLR/Vpp pin function is MCLR.)

// CONFIG5
#pragma config CP = OFF // UserNVM Program memory code protection bit (Program Memory code protection disabled)
#pragma config CPD = OFF // DataNVM code protection bit (Data EEPROM code protection disabled)

#include <xc.h>

int GPSh1;
int GPSh2;
int GPSm1;
int GPSm2;
int GPSs1;
int GPSs2;

unsigned getSPBRG(unsigned baudrate, char brg16, char brgh) {
    unsigned mult;
    if (brg16 == 0 && brgh == 0) mult = 64;
    else if (brg16 == 1 && brgh == 1) mult = 4;
    else mult = 16;

    // baudrate = fOsc / (mult*(spbrg + 1))
    // baudrate * (spbrg + 1) = fOsc / mult
    // spbrg + 1 = (fOsc / mult) / baudrate
    // spbrg = (fOsc / mult) / baudrate - 1
    return (_XTAL_FREQ / mult) / baudrate - 1;
}

char getch(){
    if (OERR) {
        CREN = 0;
        Nop();
        CREN = 1;
    }
    while(!RCIF);
    return RCREG;
}

void printSerial(char* txt, char ch) {
    while(*txt) {
        TXREG = *txt;
        txt++;
        while (!TXIF);
    }
    TXREG = ch;
    while (!TXIF);
    TXREG = '\n';
    while (!TXIF);
}

void GPStime(){
    char x = 0;
    x = getch(); if(x != '$') return;
    printSerial("Got $", ' ');
    x = getch(); printSerial("Got: ", x); if(x != 'G') { printSerial("Quitting"); return; }
    x = getch(); printSerial("Got: ", x); if(x != 'P') { printSerial("Quitting"); return; }
    x = getch(); printSerial("Got: ", x); if(x != 'G') { printSerial("Quitting"); return; }
    x = getch(); printSerial("Got: ", x); if(x != 'L') { printSerial("Quitting"); return; }
    x = getch(); printSerial("Got: ", x); if(x != 'L') { printSerial("Quitting"); return; }

    {
        char ch;
        LATA0 = 0;
        do {
            ch = getch();
            printSerial("Got: ", ch);
        } while (ch != 'E' && ch != 'W');
        char comma = getch(); // read a comma
        printSerial("Got: ", comma);
        GPSh1 = getch() - '0';
        printSerial("Got: ", GPSh1 + '0');
        GPSh2 = getch() - '0';
        printSerial("Got: ", GPSh2 + '0');
        GPSm1 = getch() - '0';
        printSerial("Got: ", GPSm1 + '0');
        GPSm2 = getch() - '0';
        printSerial("Got: ", GPSm2 + '0');
        GPSs1 = getch() - '0';
        printSerial("Got: ", GPSs1 + '0');
        GPSs2 = getch() - '0';
        printSerial("Got: ", GPSs2 + '0');
    }

}

void main(void)
{
    TRISA = 0b00000000;
    TRISB = 0b00000000;

    // LATA = 1; __delay_ms(1000);

    PORTC = 0;
    TRISC = 0b10000000; // all outputs, except RX on RC7
    ANSELC = 0b00000000; // disable analog

    RC6PPS = 0x10;

    //init USART
    // SPEN RX9 SREN CREN ADDEN FERR OERR RX9D
    RCSTA = 0b00110000; // TX9D=0 -->8-bit; SPEN=1, CREN=1, addr-det disabled.
    // CSRC TX9 TXEN SYNC SENDB BRGH TRMT TX9D
    TXSTA = 0b00100100; // TX9D=0 -->8-bit; BRGH=1; TXEN=1 --> enable, SYNC=0 --> async
    //ABDOVF RCIDL NOP SCKP BRG16 NOP WUE ABDEN
    BAUDCON = 0b00001000; // SCKP=0 -> not inverted, BRG16=1, WUE=0, ABDEN=0
    SPEN = 1;

    // LATA = 2; __delay_ms(1000);

    unsigned brg = getSPBRG(9600, 1, 1);
    SPBRGL = brg & 0xFF;
    SPBRGH = brg >> 8;

    // LATA = 3; __delay_ms(1000);

    while(1){
        GPStime();
        TXREG = GPSh1 + '0';
        while (!TXIF);
        TXREG = GPSh2 + '0';
        while (!TXIF);
        TXREG = GPSm1 + '0';
        while (!TXIF);
        TXREG = GPSm2 + '0';
        while (!TXIF);
        TXREG = GPSs1 + '0';
        while (!TXIF);
        TXREG = GPSs2 + '0';
        while (!TXIF);
        TXREG = '\n';
        while (!TXIF);
    }

    LATA = 7;
    return;
}