/////////////////////////////////////////////////////////////////////////
////              GPS Disciplined OscillatorRef10Mhz.C               ////
////                              V2p                                ////
////                 PLL lock detection based on EFC                 ////
/////////////////////////////////////////////////////////////////////////

#include <16F88.h>
#device adc=16

#FUSES NOWDT                  //No Watch Dog Timer
#FUSES HS                     //Crystal osc >= 4mhz
#FUSES NOPUT                  //No Power Up Timer
#FUSES NOMCLR                 //Master Clear pin used for I/O
#FUSES NOBROWNOUT             //No brownout reset
#FUSES NOLVP                  //No low voltage prgming, B3(PIC16) or B5(PIC18) used for I/O
#FUSES NOCPD                  //No EE protection
#FUSES NOWRT                  //Program memory not write protected
#FUSES NODEBUG                //No Debug mode for ICD
#FUSES NOPROTECT              //Code not protected from reading
#FUSES NOFCMEN                //Fail-safe clock monitor disabled
#FUSES NOIESO                 //Internal External Switch Over mode disabled

#use delay(clock=10000000)
#define PIN_AUX4        PIN_A0      // AUX I/O no.4
#define PIN_AUX3        PIN_A1      // AUX I/O no.3
#define PIN_AUX1        PIN_A2      // AUX I/O no.1
#define PIN_LOCK_LED    PIN_A4      // (LED5) PLL LOCK status LED
#define PIN_SATS_LED    PIN_A3      // (LED4) SATS IN USE status LED
#define PIN_AUX2        PIN_A5      // AUX I/O no.2 ** input only **
#define PIN_ACQ_LED     PIN_B0      // (LED3) GPS AQUIRING LED
#define PIN_OVEN_LED    PIN_B1      // (LED2) OCXO OVEN status LED
#define PIN_RX          PIN_B2      // SERIAL data in
#define PIN_POWER_LED   PIN_B3      // (LED1) POWER ON status LED
#define PIN_OVEN        PIN_B4      // OVEN TEMP STATUS from OCXO
#define PIN_TX          PIN_B5      // SERIAL data out
#define PIN_OCV         PIN_B6      // Declared here but "sAN5" used in code
//#define PIN_B7        PIN_B7      // UNUSED
#use rs232(baud=4800,parity=N,xmit=PIN_TX,rcv=PIN_RX,bits=8)

// Constants
#define EFC_thr         16    // EFC stability counter thresold (max 254)

// Variables
   int i;                     // General purpose
   int OVEN_old=0;            // Oven status register
   int OVEN_new=0;            // New oven status
   int SATS_old=0;            // Number of satellites in use register
   int SATS_new=0;            // New numer of satellites in use
   int REF_lock_old=0;        // Reference lock status register
   int REF_lock_new=0;        // New reference lock status   
   int EFC_osc=0;             // EFC value oscillation counter
   int EFC_rep=0;             // EFC value repeated counter
   int16 EFC_1=0;             // EFC value 1 register
   int16 EFC_2=0;             // EFC value 2 register
   int16 EFC_new=0;           // New OCV value

// Functions

void NewLine(){
   printf("\r\n");
}

void CheckSATS() {
   char CH=0x00;              // NMEA data char
         
   // We look for $GPGGA (simplified to xxxxG). If fifth character is not "G",
   // we discard this sentence and study the next one.
   // ( At 4800bps, NMEA shows a bit time of 208.33uS )
   while (CH!='G') {
   
      // Wait for current NMEA sentence to finish
      setup_timer_0(RTCC_INTERNAL|RTCC_DIV_128);
      set_rtcc(0);
      while (get_rtcc()<90)  // 0,4uS*128 / Count
         if (!input(PIN_RX)) set_rtcc(0);
 
      // Prepare UART to start receiving the next NMEA sentence
      setup_uart(false);      // Turn UART off and on to discard overrun errors
      setup_uart(true);
      if (kbhit())            // Empty the two-char buffer
      CH=getc();
      if (kbhit())
      
      // Get the 5th char
      CH=getc();              // get 1st character, which is "$"
      CH=getc();              // get 2nd & discard 1st
      CH=getc();              // get 3rd & discard 2nd
      CH=getc();              // get 4th & discard 3rd
      CH=getc();              // get 5th & discard 4th
   };
    
   // Skip 6 commas and stay in the 6th one
   i=0;
   while (i<6) {
      CH=getc();
      if (CH==',') i++;
   };

   // Parse number of sats in use
   CH=getc();
   if (CH=='1') {             // Check for 2D or 3D fix
      CH=getc();              // Skip the comma
      CH=getc();              // Get the tens in number of sats
      if (CH=='0'){
         CH=getc();           // 9 or less sats in use, get the number
         SATS_new=CH-'0';     // Convert the char to number
      }
      else {
         CH=getc();           // More than 9 sats in use, get the number
         SATS_new=CH-'0';     // Conver the char to number
         SATS_new=SATS_new+10;// Add 10 to the units
      }
   }
   else
      SATS_new=0;                 // No fix, zero sats in use
      
   // Update SATS and send the new number via RS232 if changed
   if (SATS_new!=SATS_old)
      if (SATS_new==0){
         printf("$GPS,nofix");
         NewLine();
         }
      else
         if (SATS_old==0){
         printf("$GPS,fix");
         NewLine();
         };
      
   SATS_old=SATS_new;
   
   // Blink the satellites LED
   if (SATS_new==0){              // No sats, long blink
      output_high(PIN_ACQ_LED);
      delay_ms(250);
      output_low(PIN_ACQ_LED);
   }
   else
      for (i=0;i<SATS_new;i++){   // Blink the number of sats in use
      output_high(PIN_SATS_LED);
      delay_ms(50);
      output_low(PIN_SATS_LED);
      delay_ms(200);
   };
}

void CheckOVEN() {

   // OXC Temperature Monitor Out check
   OVEN_new=input(PIN_OVEN);
   
   // Update OVEN and send the new value via RS232 if changed
   if (OVEN_new!=OVEN_old){
      
      if (OVEN_new){
         output_high(PIN_OVEN_LED);
         printf("$OVEN,hot");
         NewLine();         
       }
       else {
          output_low(PIN_OVEN_LED);
          printf("$OVEN,cold");
          NewLine();
       }
       
       OVEN_old=OVEN_new;
   };
}

void CheckEFC() {

   EFC_new=read_adc()/64;
   
   // Compare new EFC value with EFC_1&2 and update EFC registers
   
   if (EFC_new==EFC_2){              // EFC remains constant
      EFC_osc=EFC_osc+1;
      EFC_rep=EFC_rep+1;
      }
   else
      if (EFC_new==EFC_1){          // EFC returned to previous value
         EFC_osc=EFC_osc+1;
         EFC_rep=1;
         EFC_1=EFC_2;               // Place EFC_1 & EFC_2 in correct order
         EFC_2=EFC_new;
         }
      else{                         // EFC different than EFC_1 & EFC_2
            EFC_osc=EFC_rep;
            EFC_rep=1;
            EFC_1=EFC_2;
            EFC_2=EFC_new;
            };
   
   if (EFC_osc==255)         // Prevent EFC_osc from increasing forever
      EFC_osc=254;
      
   if (EFC_rep==255)         // Prevent EFC_rep from increasing forever
      EFC_rep=254;
       
   printf("$EFC,%Lu",EFC_1);
   printf(",%Lu",EFC_2);
   printf(",%u",EFC_osc);   
   printf(",%u",EFC_rep);      
   NewLine();      
         
}

void CheckLock(){
   
   // // Update status depending on new EFC register values
   
   if (SATS_new==0){
      ref_lock_new=0;
      EFC_osc=0;
      EFC_rep=0;
      }
      
   else
      if (EFC_osc>=EFC_thr)
         REF_lock_new=1;
      else
         REF_lock_new=0;
      
   if (REF_lock_new!=REF_lock_old)
      if (REF_lock_new){
         output_high(PIN_LOCK_LED);
         printf("$REF,lock");
         NewLine();
         }
      else{
         output_low(PIN_LOCK_LED);
         printf("$REF,unlock");
         NewLine();
         };   
 
   REF_lock_old=REF_lock_new;
   
}

void StrobeLeds(){
   output_high(PIN_B3); delay_ms(50);   // LED1
   output_high(PIN_B1); delay_ms(50);   // LED2
   output_high(PIN_B0); delay_ms(50);   // LED3
   output_high(PIN_A3); delay_ms(50);   // LED4
   output_high(PIN_A4); delay_ms(50);   // LED5
   output_low(PIN_B3);  delay_ms(50);   // LED1
   output_low(PIN_B1);  delay_ms(50);   // LED2
   output_low(PIN_B0);  delay_ms(50);   // LED3
   output_low(PIN_A3);  delay_ms(50);   // LED4
   output_low(PIN_A4);  delay_ms(50);   // LED5
   delay_ms(500);
}

void main()
{
   
   // Wizard Generated Code
   setup_adc_ports(sAN5|VSS_VDD);
   setup_adc(ADC_CLOCK_DIV_32);
   set_adc_channel(5);
   setup_spi(SPI_SS_DISABLED);
   setup_timer_1(T1_DISABLED);
   setup_timer_2(T2_DISABLED,0,1);
   setup_comparator(NC_NC_NC_NC);
   setup_vref(FALSE);

   //User Code
   printf("EB4EQA GPSDO v2.0");
   NewLine();
   
   StrobeLeds();
   
   output_high(PIN_POWER_LED);
   
   while (TRUE) {
      CheckOVEN();
      CheckSATS();
      CheckEFC();
      CheckLOCK();
   };

}