/* 
 * File:   RX_RF.c
 * Author: George Panagopoulos
 *
 * Created on 16 Oct 2016, 8:17
 */
#ifndef _XTAL_FREQ
#define _XTAL_FREQ 4000000 //4Mhz FRC internal osc
#define __delay_us(x) _delay((unsigned long)((x)*(_XTAL_FREQ/4000000.0)))
#define __delay_ms(x) _delay((unsigned long)((x)*(_XTAL_FREQ/4000.0)))
#endif
#include <stdio.h>
#include <stdlib.h>
#include <stdint.h>
#include <string.h>
#include <xc.h>
#include "lcd.h"

// BEGIN CONFIG
#pragma config FOSC = INTRC_CLKOUT  // Oscillator Selection bits (INTOSCIO oscillator: I/O function on RA6/OSC2/CLKOUT pin, I/O function on RA7/OSC1/CLKIN)
#pragma config WDTE = OFF           // Watchdog Timer Enable bit (WDT disabled and can be enabled by SWDTEN bit of the WDTCON register)
#pragma config PWRTE = OFF          // Power-up Timer Enable bit (PWRT disabled)
#pragma config MCLRE = ON           // RE3/MCLR pin function select bit (RE3/MCLR pin function is digital input, MCLR internally tied to VDD)
#pragma config CP = OFF             // Code Protection bit (Program memory code protection is disabled)
#pragma config CPD = OFF            // Data Code Protection bit (Data memory code protection is disabled)
#pragma config BOREN = OFF          // Brown Out Reset Selection bits (BOR disabled)
#pragma config IESO = OFF           // Internal External Switchover bit (Internal/External Switchover mode is disabled)
#pragma config FCMEN = OFF          // Fail-Safe Clock Monitor Enabled bit (Fail-Safe Clock Monitor is enabled)
#pragma config LVP = OFF            // Low Voltage Programming Enable bit (RB3/PGM pin has PGM function, low voltage programming enabled)
 
#define PAYLOAD_SIZE        16

uint8_t rxdata;
uint8_t parity;
uint8_t rxbuffer[PAYLOAD_SIZE];        // Buffer for storing received data 
uint8_t rxidx;                         // buffer index
uint8_t rxdatacoming;
uint8_t rxdataready;

void usart_send(uint8_t txbyte) {

    while(!TXSTAbits.TRMT);     // make sure buffer full bit is high before transmitting
    TXREG = txbyte;             // transmit data
}

//used for debugging. send data to PC 
void usart_write_string(const char *str,int length)
{
    int cnt=0;
    for(cnt=0;cnt<length;cnt++)
    {
      usart_send(str[cnt]);
    }
    usart_send(13);    
    usart_send(10);
}
void interrupt ISR(void)
{
    //interrupts cannot be interrupted
    //automatically sets GIE on return from interrupt, which re enable interrupts.

    if (RCIE && RCIF)       //is interrupt occured by EUSART receive?,
    {                       //then RCREG is full we have new data (cleared when RCREG is read)         
        rxdata = RCREG;      
        
        if(RCSTAbits.OERR)
       {
           do
           {
               RCSTAbits.CREN = 0;
               RCSTAbits.CREN = 1;
           }
           while(RCSTAbits.OERR);
       }
       else if(RCSTAbits.FERR)
       {
           RCSTAbits.CREN = 0;
           RCSTAbits.CREN = 1;
       }
       else
       {                                 
           if(rxdata == '@')                        //start byte detected. start reading data
           {
               rxdatacoming=1;
               rxidx=0;
           }
           else if(rxdatacoming==1 && rxdata =='*') //stop byte detected
           {      
               lcd_clear();        
               lcd_set_cursor(1,1);              
               lcd_write_string_s(rxbuffer,PAYLOAD_SIZE);              
               usart_write_string(rxbuffer,PAYLOAD_SIZE);
               rxidx=0;                  
               memset(rxbuffer,NULL,sizeof(rxbuffer)); 
               rxdatacoming=0;
           }
           else if(rxdatacoming==1)
           {
               rxbuffer[rxidx] = rxdata;    // read new data into variable
               rxidx++;                    //increment RX buffer pointer
               
               if(rxidx>PAYLOAD_SIZE+1)     //+ stop byte
               {                
                   rxidx=0;                //init RX buffer pointer               
                   rxdatacoming=0; 
               }
           }
       }
        
        RCIF = 0;      // clear interrupt flag
    }
  }

void usart_init(uint16_t baud_rate,int en_RX)
{
    //SPBRG
    switch(baud_rate)
    {
     case 1200:
        SPBRG=207;
        break;
     case 2400:
        SPBRG=103;
        break;
     case 9600:
        SPBRG=25;
        break;
    }
    //TXSTA
    TXSTAbits.TX9=0;  //8 bit transmission
    TXSTAbits.TXEN=1; //Transmit enable
    TXSTAbits.SYNC=0; //Async mode
    TXSTAbits.BRGH=1; //High speed baud rate

    //RCSTA
    RCSTAbits.SPEN=1;   //Serial port enabled
    RCSTAbits.RX9=0;    //8 bit mode

    if(en_RX)
    {
        RCSTAbits.CREN=1;   //Enable receive
        RCSTAbits.ADDEN=0;  //Disable address detection

        RCIF=0;             //make sure receive interrupt flag is clear
        RCIE=1;             //enable UART receive interrupt
        PEIE=1;             //enable peripheral interrupt
        
        ei();
    }
}
void init_io(void) {
    ANSEL = 0x00;         // NO ADC
    ANSELH = 0x00;        //
    CM1CON0 = 0x00;       //No comparators
    CM2CON0 = 0x00;
 
    TRISA= 0;             // all output    
 
    PORTB = 0x00;
    TRISB= 0;             // all output

    TRISCbits.TRISC0 = 0; // output
    TRISCbits.TRISC1 = 0; // output
    TRISCbits.TRISC2 = 0; // output
    TRISCbits.TRISC3 = 0; // output
    TRISCbits.TRISC4 = 0; // output
    TRISCbits.TRISC5 = 0; // output
    TRISCbits.TRISC6 = 0; // UART TX
    TRISCbits.TRISC7 = 1; // UART RX
 
    PORTD=0x00;
    TRISD = 0;            // all output
 
    TRISEbits.TRISE0 = 1; // input
    TRISEbits.TRISE1 = 1; // input
    TRISEbits.TRISE2 = 1; // input
    TRISEbits.TRISE3 = 1; // /MCLR
}
int main()
{
    OSCCONbits.IRCF = 0x06; //set OSCCON IRCF bits to select internal OSC frequency 4MHz
  
    init_io();
    lcd_init();
    
    usart_init(1200,1);         //initialise UART     
    __delay_ms(100);            //Wait for UART module to stabilise  
  
  while(1)
  {                  
    //could sleep and wake up 
    //on UART interrupt for low power applications
    __delay_ms(100);  
  }
  return 0;
}