/*
 * File:   TX_RF.c
 * Author: George Panagopoulos
 * Processor: PIC12F1822
 *
 * Created on 06 Nov 2016, 13:00
 *
 *          
 */

#include <stdio.h>
#include <stdlib.h>
#include <stdint.h>
#include <string.h>
#include <xc.h>



// CONFIG1
#pragma config FOSC = XT        // Oscillator Selection (XT Oscillator, Crystal/resonator connected between OSC1 and OSC2 pins)
#pragma config WDTE = ON       // Watchdog Timer Enable (WDT enabled)
#pragma config PWRTE = ON       // Power-up Timer Enable (PWRT ENABLED)
#pragma config MCLRE = OFF      // MCLR Pin Function Select (MCLR/VPP pin function is digital input)
#pragma config CP = OFF         // Flash Program Memory Code Protection (Program memory code protection is disabled)
#pragma config CPD = OFF        // Data Memory Code Protection (Data memory code protection is disabled)
#pragma config BOREN = OFF       // Brown-out Reset Enable (Brown-out Reset enabled)
#pragma config CLKOUTEN = OFF   // Clock Out Enable (CLKOUT function is disabled. I/O or oscillator function on the CLKOUT pin)

// CONFIG2
#pragma config WRT = OFF        // Flash Memory Self-Write Protection (Write protection off)
#pragma config PLLEN = OFF      // PLL Enable (4x PLL disabled)
#pragma config STVREN = OFF     // Stack Overflow/Underflow Reset Enable (Stack Overflow or Underflow will not cause a Reset)
#pragma config BORV = LO        // Brown-out Reset Voltage Selection (Brown-out Reset Voltage (Vbor), low trip point selected.)
#pragma config LVP = OFF        // Low-Voltage Programming Enable (High-voltage on MCLR/VPP must be used for programming)

#define _XTAL_FREQ          4000000      //4MHZ external oscillator used in _delay()


void enable_uart(int enable)
{
    RCSTAbits.SPEN=enable;   //Serial port enabled
    
    if(enable)
        __delay_ms(12);      //let receiver adjust its gain
}
void init_usart(uint16_t baud_rate)
{
    //SPBRG
    switch(baud_rate)
    {
     case 1200:
        SPBRG=207;
        break;
     case 2400:
        SPBRG=103;
        break;
     case 9600:
        SPBRG=25;
        break;
    }
  
    TXSTAbits.SYNC =0;  //Async mode
    RCSTAbits.SPEN=1;   //Serial port enabled
     
    //TXSTA
    TXSTAbits.TX9=0;  //8 bit transmission
    TXSTAbits.TXEN=1; //Transmit enable
    TXSTAbits.BRGH=1; //High speed baud rate
}


void usart_write_char(char txbyte)
{
  while(!PIR1bits.TXIF);
  TXREG=txbyte;
}
void send_preamble()
{
    int i;
    for(i=0;i<5;i++)
    {     
        usart_write_char(0xf8);
    }
    usart_write_char(0xfA);
}
void send_start_byte()
{
    usart_write_char('@');
}
void send_stop_byte()
{    
    usart_write_char('*');
}
void USARTWriteString(const char *str,int length,int repeat)
{
    int i,k=0;
      
    for(k=0;k<repeat;k++)
    {
        send_preamble();
        send_start_byte();
        for(i=0;i<length;i++)
        {
            usart_write_char(str[i]);
        }
        send_stop_byte();
    }
}

void watchdog_sleep(void) {
    WDTCONbits.SWDTEN = 0b1;
    SLEEP();
    WDTCONbits.SWDTEN = 0b0;
}

int main(int argc, char** argv)
{
    char* tx_message = (char*)"Hello InstWorld!";
   
    //configure PORT
    CPSCON0bits.CPSON=0;    //disable capacitive sensing!
    ANSELA=0;               //set all analog pins to digital I/O
    TRISA=0b000010;         //configure RA0 as output (USART TX)
                            //RA1 input (USART RX)
    LATA=0;                 //all output pins low.
    OPTION_REGbits.PSA = 1; //assign prescaler to WDT
    OPTION_REGbits.PS=0b111;//prescale = 128
                            //->WDT timeout = 2.3s
    init_usart(1200);

    while(1)
    {            
        enable_uart(1);
        USARTWriteString(tx_message,16,1);  
        __delay_ms(100);             //LET UART TRANSMISSION FINISH UP!     
        enable_uart(0);
        watchdog_sleep();            //enter sleep mode until WDT timeout 
    }
    return (EXIT_SUCCESS);
}