#include <p24fxxxx.h>

_CONFIG2(FNOSC_FRCPLL & OSCIOFNC_ON &POSCMOD_NONE & I2C1SEL_PRI)      // Internal FRC OSC = 8MHz
_CONFIG1(JTAGEN_OFF & GCP_OFF & GWRP_OFF & COE_OFF & FWDTEN_OFF & ICS_PGx1) //turn off junk we don't need

#define VREG_DIR TRISAbits.TRISA0     //sets VREG33_DIR to TRISBIT A0
#define VREG_EN LATAbits.LATA0        //sets VREG_EN to LAT bit A0 (output latch)
#define MODE_LED_DIR TRISAbits.TRISA1   //sets the MODE_LED_DIR to TRISBIT A1
#define MODE_LED LATAbits.LATA1         //sets the MODE_LED to LAT bit A1 (output latch)

#pragma code


void initADC();
unsigned int getADC();
unsigned char UART1RX(void);
void UART1TX(char c);
void InitializeUART1(void);

//this loop services user input and passes it to be processed on <enter>
int main(void){

   CLKDIVbits.RCDIV0=0; //clock divider to 0
   AD1PCFG = 0xFFFF;    // Default all pins to digital
   OSCCONbits.SOSCEN=0; //Oscilator setup, registar-OSCON bits-SOSCEN
   MODE_LED_DIR = 0;    //Mode LED set as output
   VREG_DIR =0;       //VREG is set as output
   VREG_EN = 1;       //Sets the VREG pin to 1, turns on the Voltage regulators.
   MODE_LED = 1;    //Turns the MOD LED 0N

   InitializeUART1(); //Initialize UART1
   initADC();         //Initialise ADC  

   unsigned int voltage;

   /////FOREVER///LOOP//////////
   while(1)
   {
      if(UART1RX() == 'a')  //Checks if the recived byte is 'a' if so it sends the two RAW bytes form ADC
      {
         voltage = getADC(); //reads the ADC pin
         UART1TX(voltage>>8); //seds the top byte of ADC to UART
         UART1TX(voltage);    //sends the bottom byte of ADC to UART
      }   
   }
}

////////////////////////////////////////////////////////////////////////////////////
/////Analog to digital converter intitilisationn function///////////////////////////
/////Setch the ADC to read the AN12 chanel, whic is connected ot the BPv3 pin ADC///
////////////////////////////////////////////////////////////////////////////////////
void initADC()
{
//////////////////////////////////////////////////////////////
///////////////ADC config//////////////////////////////////
   AD1PCFGbits.PCFG12=0;//B12/AN12/ADC1/EXT

   //configure the ADC
   AD1CON1bits.SSRC  = 0b111;// SSRC<3:0> = 111 implies internal
                           // counter ends sampling and starts
                           // converting.
   AD1CSSL = 0;
   AD1CON3 = 0x1F02; // Sample time = 31Tad,
                     // Tad = 2 Tcy
   AD1CON2 = 0;   //CSCNA =0 -does not scan inputs,
               //BUFS =0 -A/D is currently filling buffer 00-07,
               //SMPI=0 -Interrupts at the completion of conversion for each sample/convert sequence,
               //BUFM =0 -Buffer configured as one 16-word buffer,
               //ALTS = 0 -Always uses MUX A input multiplexer settings

   AD1CHS =12;           //chanell selected 12, this is the AN12 pin which is conected to the voltage devider and the ADC pin on the BPv3
/////////////////////////////////////////////////////////////////
}

unsigned int getADC()
{
    AD1CON1bits.ADON =1; //turns the ADC module on
   AD1CON1bits.SAMP=1;  //start sample
    AD1CON1bits.DONE=0;  //starts conversion
   while(AD1CON1bits.DONE==0);//wait for conversion to finish
   AD1CON1bits.ADON =0; //turns the ADC module off
   return ADC1BUF0;
}


//get a byte from UART
unsigned char UART1RX(void){

    while(U1STAbits.URXDA == 0);
   return U1RXREG;
}

//add byte to buffer, pause if full
//uses PIC 4 byte UART FIFO buffer
void UART1TX(char c){
   while(U1STAbits.UTXBF == 1); //if buffer is full, wait
    U1TXREG = c;
}

//Initialize the terminal UART for the speed currently set in bpConfig.termSpeed
void InitializeUART1(void){
   
   TRISBbits.TRISB4=1; //UART 1 RX set as input
   //set pin configuration using peripheral pin select
      RPINR18bits.U1RXR = 5; // UART1 RX assign to RP5
     RPOR2bits.RP4R = 3; //UART1 TX assign to RP4

    U1BRG = 34;//13332=300, 1666=2400, 416=9600, 34@32mhz=115200....
    U1MODE = 0;
    U1MODEbits.BRGH = 1;
    U1STA = 0;
    U1MODEbits.UARTEN = 1;
    U1STAbits.UTXEN = 1;
    IFS0bits.U1RXIF = 0;
}