/*
ADC and Serial UART Test Program
Date: 7-21-05
Author: Evan Dudzik

This program is an example of interfacing with two pieces of hardware within the PIC:
the analog to digital converter, and the UART, as well as using interrupts.

The program continuously reads the ADC value, and when it changes, outputs it via serial.
The output can be either a single character (0-255),
	or encoded to ASCII decimal for easy viewing in a terminal,
	by simply commenting out the appropriate line in the main function.
	
As a simple test, the program also echos recieved characters back to the host.
This way you can type in a terminal program to check the serial communication.
*/

#include <system.h>
#pragma DATA 0x2007, 0x3F50//_INTRC_IO & _WDT_OFF & _LVP_OFF

//important bits in SFR's for ADC, UART, and interrupt.
volatile bit go @ ADCON0.GO;
volatile bit gie @ INTCON.GIE;
volatile bit rcie @ PIE1.RCIE;
volatile bit peie @ INTCON.PEIE;
volatile bit rcif @ PIR1.RCIF;
volatile bit trmt @ TXSTA.TRMT;

char data_in;
bit newdata;

//interrupt service routine
void interrupt(void)
{
    if(rcif) //UART Recieve Interrupt
    {
        data_in = rcreg;
        newdata = 1;
        rcreg = 0;
    }
}
//Function: Reads one value from the ADC
//Returns: most significant byte of result
inline char adc_read()
{
	go=1;
	while(go);
	return adresh;
}

//Function: sends a single byte with the hardware serial UART.
inline void sendbyte(char b)
{
    txreg=b;
    while(!trmt) {};
}

//Function: Sends a character as ASCII decimal
void senddecimal(char b)
{
	char temp, temp2;
	temp=b;
	temp2=temp/100;
	sendbyte('<');
	sendbyte(temp2+'0');
	temp=temp%100;
	temp2=temp/10;
	sendbyte(temp2+'0');
	temp=temp%10;
	sendbyte(temp+'0');
	sendbyte('>');
}

void main()
{
	//*********************//
	// configure I/O ports //
	//*********************//
    portb   = 00000000b;
    trisb   = 11111111b; //0 = Output, 1 = Input
    porta   = 00000000b;     
    trisa   = 11111111b; //0 = Output, 1 = Input
    
    //***************//
    // configure ADC //
    //***************//

    osccon  = 01110000b; //internal oscillator @ 8MHz
    cmcon   = 00000111b; //comparators off
    ansel   = 00000001b; //AN0 on (RA0)
    adcon1  = 00000000b; //left justified, fosc/2 clock, Vdd & Vss ref voltages
    adcon0  = 00000001b; //set to AN0, ADC operating
    
    //*****************//
    // configure USART //
    //*****************//
    
	spbrg = 51; 		//9600 baud @ 8MHz
    txsta=00100100b; 	//full duplex asynchronous
    rcsta=10010000b; 	//full duplex asynchronous
    rcie = 1;			//enable RX interrupt
    peie = 1;			//enable peripheral interrupts (needed for RX)
    gie = 1;			//global interrupt enable
    
    char adcval,temp;
    
    while(1)
    {
		temp=adc_read();
		if(temp!=adcval)
		{
			adcval=temp;
			sendbyte(adcval);
			//senddecimal(adcval); //use this instead for clearer output in hyperterminal
		}			
		if(newdata){newdata=0; sendbyte(data_in);}
		delay_ms(5);	                
    }
}