/*
 * File:   main.c
 * Author: boos
 *
 * Created on January 18, 2020, 6:39 PM
 */

// CONFIG1
#pragma config FOSC = INTOSC    // Oscillator Selection Bits (INTOSC oscillator: I/O function on CLKIN pin)
#pragma config WDTE = OFF       // Watchdog Timer Enable (WDT disabled)
#pragma config PWRTE = OFF      // Power-up Timer Enable (PWRT disabled)
#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 BOREN = ON       // 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)
#pragma config IESO = OFF       // Internal/External Switchover Mode (Internal/External Switchover Mode is disabled)
#pragma config FCMEN = OFF      // Fail-Safe Clock Monitor Enable (Fail-Safe Clock Monitor is disabled)

// CONFIG2
#pragma config WRT = OFF        // Flash Memory Self-Write Protection (Write protection off)
#pragma config CPUDIV = CLKDIV6 // CPU System Clock Selection Bit (CPU system clock divided by 6)
#pragma config USBLSCLK = 48MHz // USB Low SPeed Clock Selection bit (System clock expects 48 MHz, FS/LS USB CLKENs divide-by is set to 8.)
#pragma config PLLMULT = 3x     // PLL Multipler Selection Bit (3x Output Frequency Selected)
#pragma config PLLEN = ENABLED  // PLL Enable Bit (3x or 4x PLL Enabled)
#pragma config STVREN = ON      // Stack Overflow/Underflow Reset Enable (Stack Overflow or Underflow will cause a Reset)
#pragma config BORV = LO        // Brown-out Reset Voltage Selection (Brown-out Reset Voltage (Vbor), low trip point selected.)
#pragma config LPBOR = OFF      // Low-Power Brown Out Reset (Low-Power BOR is disabled)
#pragma config LVP = OFF        // Low-Voltage Programming Enable (High-voltage on MCLR/VPP must be used for programming)

#include <xc.h>
#define _XTAL_FREQ 4000000

// auxiliary variables
char dac_value = 0;
char dir = 1;

void main(void) {
    
     // set internal oscillator to 4MHz
    IRCF0 = 1;
    IRCF1 = 0;
    IRCF2 = 1;
    IRCF3 = 1;
    
    // turn off ADC settings for DAC pins
    TRISC2 = 0;
    TRISC3 = 0;
    ANSC2 = 0;
    ANSC3 = 0;
    
    // DAC source: VDD
    D1PSS0 = 0;
    D1PSS1 = 0;
    
    // enable DAC output 1, but NOT output 2
    DACOE1 = 1;
    DACOE2 = 0;
    
    // switch DAC on
    DACEN = 1;
    
    // main loop
    while (1) {
        
        // increase or decrease DAC value
        dac_value += dir;
        if (dac_value >= 31) {
            dir = -1;
        } else if (dac_value == 0) {
            dir = 1;
        }
        
        // write DAC value into DAC register
        DACR0 = dac_value & 1;
        DACR1 = (dac_value & 2) >> 1;
        DACR2 = (dac_value & 4) >> 2;
        DACR3 = (dac_value & 8) >> 3;
        DACR4 = (dac_value & 16) >> 4;
        
        // wait 100ms
        __delay_ms(100);
        
    }
    
    return;
    
}