// PIC18F14K50 in C - Versione 1.0 - Ottobre 2014
// Copyright (c) 2014 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

// ADC (8 bit) - Interrupt (debug)

#define VREF 3.20

#include "configurationbits.h"
// Note for 48 MHz clock:
// #pragma config FOSC = HS        // Oscillator Selection bits (HS oscillator)
// #pragma config PLLEN = ON       // 4 X PLL Enable bit (Oscillator multiplied by 4)

#define SAMPLES 16 // Buffer size

unsigned char volatile buffer[SAMPLES]; // Data samples from ADC
unsigned int volatile samples_in_buffer; // How many samples un buffer?

void display(unsigned voltage);

void main(void) // Program start here
{
    // Configure digital port
    TRISC = 0x00; // Port C as output

    // COnfigure ADC and analog port
    TRISBbits.RB5 = 1; // Disable digital output buffer on AN11/RB5
    ANSELHbits.ANS11 = 1; // Disable digital input buffer for AN11
    ADCON2bits.ADFM = 0; // Left justified
    ADCON2bits.ADCS = 0b110; // A/D Conversion Clock = FOSC/64 (1.33 us @ 48 MHz)
    ADCON2bits.ACQT = 0b001; // A/D Acquisition time set to 2 TAD
    ADCON1 = 0; // Set VDD and VSS as voltage reference
    ADCON0bits.CHS = 0b1011; // Analog Channel Select AN11

    // Configure interrupt
    RCONbits.IPEN = 1; // Enable priority levels on interrupts
    PIE1bits.ADIE = 1; // Enable interrupt from ADC
    IPR1bits.ADIP = 1; // Set ADC high priority interrupt
    PIR1bits.ADIF = 0; // Clear interrupt status to avoid automatic interrupt ad "boot time"
    INTCONbits.GIEH = 1; // Enables high priority interrupts

    ADCON0bits.ADON = 1; //  Power ON ADC
    ADCON0bits.GO = 1; // Start first conversion

    while (1) {
        display(buffer[samples_in_buffer]);
    }
}

void display(unsigned voltage) {

    voltage = voltage + 16;
    voltage = (voltage >> 5);
    PORTC = ~(0xFF << voltage);
}

void interrupt __high_priority my_isr_high(void) {
    if (PIR1bits.ADIF) // Interrupt from ADC?
    {
        buffer[samples_in_buffer] = ADRESH; // Read ADC value - 8 bit
        ADCON0bits.GO = 1; // Start new conversion
        samples_in_buffer++; // Point to next buffer
        if (samples_in_buffer >= SAMPLES) {
            //PIE1bits.ADIE = 0; // Buffer full - Disable interrupt from ADC
            samples_in_buffer = 0; // Buffer full - Empty 
        }
        PIR1bits.ADIF = 0; // Clear interrupt status
    }
}