// PIC18 in C - Versione 0.85 - Ottobre 2015
// Copyright (c) 2015 VincenzoV.net
// Creative Commons | Attribuzione-Condividi allo stesso modo 3.0 Unported.
// Creative Commons | Attribution-Share Alike 3.0 Unported
// https://www.vincenzov.net/tutorial/PIC18/adc.htm

// PIC18F14K50 - ADC (10 bit) - Read data sheet!
// MPLAB X / XC8

#define VREF 3.20

#include "configurationbits.h"

void main(void) 
{
    unsigned int voltage10bits; // Voltage as ten bits integer (0 -> 1023)
    double voltage;             // Voltage as floating point number 0 -> 3,3 (V)

    OSCCON = 0x70;              // Set internal clock to 16 MHz - Data sheet: REGISTER 2-1: OSCCON: OSCILLATOR CONTROL REGISTER

    // Configure I/O pins
    TRISC = 0x00;         // Port C as digital output (LEDs) - Data sheet: REGISTER 9-12: TRISC: PORTC TRI-STATE REGISTER
    TRISBbits.RB5 = 1;    // Disable digital output buffer on AN11/RB5 - Data sheet: REGISTER 9-7: TRISB: PORTB TRI-STATE REGISTER
    ANSELHbits.ANS11 = 1; // Disable digital input buffer for AN11 - Data sheet: REGISTER 9-15: ANSEL: ANALOG SELECT REGISTER 1

    // Configure ADC
    ADCON2bits.ADFM = 1;     // Right justified // Data sheet: Figure 17-2: 10-BIT A/D CONVERSION RESULT FORMAT
    ADCON2bits.ADCS = 0b101; // A/D Conversion Clock = FOSC/16 (1 us @ 16 MHz) - Data sheet: Table 17-1: ADC CLOCK PERIOD (TAD) VS. DEVICE OPERATING FREQUENCIES
    ADCON2bits.ACQT = 0b001; // A/D Acquisition time set to 2 TAD - Data sheet: 17.3 A/D Acquisition Requirements - Figure 17-4: A/D CONVERSION TAD CYCLES (ACQT<2:0> = 010, TACQ = 4 TAD)
    ADCON1 = 0;              // Set VDD and VSS as voltage reference - Data sheet: REGISTER 17-2: ADCON1: A/D CONTROL REGISTER 1
    ADCON0bits.CHS = 0b1011; // Analog Channel Select AN11 - Data sheet: REGISTER 17-1: ADCON0: A/D CONTROL REGISTER 0
    ADCON0bits.ADON = 1;     // ADC is enabled - Data sheet: REGISTER 17-1: ADCON0: A/D CONTROL REGISTER 0

    while (1) {
        ADCON0bits.GO = 1;           // Start conversion - Data sheet: REGISTER 17-1: ADCON0: A/D CONTROL REGISTER 0

        while (ADCON0bits.nDONE);    // Wait End Of Conversion - Data sheet: REGISTER 17-1: ADCON0: A/D CONTROL REGISTER 0
        
        voltage10bits = ADRESH << 8; // Read voltage - 2 MSB - Data sheet: REGISTER 17-6: ADRESH: ADC RESULT REGISTER HIGH (ADRESH) ADFM = 1
        voltage10bits |= ADRESL;     // Read voltage - 8 LSB - Data sheet: REGISTER 17-7: ADRESL: ADC RESULT REGISTER LOW (ADRESL) ADFM = 1
        
        // voltage = (double) VREF / 1024 * voltage10bits;
        LATC = voltage10bits >> 2;   // Display ADC result - Data sheet: REGISTER 9-13: LATC: PORTC DATA LATCH REGISTER
    }

}