/*
 * Digital Capacitor ESR Tester V3.1
 * Copyright (c) 2009, Regulus Berdin
 * All rights reserved. 
 * 
 * Permission is hereby granted, free of charge, to any person
 * obtaining a copy of this software and associated documentation
 * files (the "Software"), to deal in the Software without
 * restriction, including without limitation the rights to use,
 * copy, modify, merge, publish, distribute, sublicense, and/or
 * sell copies of the Software, and to permit persons to whom the
 * Software is furnished to do so, subject to the following
 * conditions:
 * 
 * The above copyright notice and this permission notice shall be
 * included in all copies or substantial portions of the Software.
 * 
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
 * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES
 * OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
 * NONINFRINGEMENT.  IN NO EVENT SHALL REGULUS BERDIN BE LIABLE FOR
 * ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF
 * CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
 * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
 * SOFTWARE.
*/ 
 
#include <16F876.h>
#device adc=10

#FUSES NOWDT, HS, NOPUT, NOPROTECT, NOBROWNOUT, NOLVP, NOCPD, NOWRT, NODEBUG
#use delay(clock=20M)


#use fast_io(a)
#use fast_io(b)
#use fast_io(c)


#define CHARGE_MASK     (1<<0)
#define DEBUG_MASK      (1<<1)
#define COM1_MASK       (1<<2)
#define COM2_MASK       (1<<3)

#define COM1_PIN        PIN_B2
#define COM2_PIN        PIN_B3

#define BUZZERP_PIN     PIN_A1
#define BUZZERN_PIN     PIN_A2

#define PASS_PIN        PIN_A5
#define FAIL_PIN        PIN_A3


float rx, fvs, fvo, fvg, fd, r1 = 3.3, r2 = 0.0;


const char led_map[16] = {
    /*
     aaaa
    f   b
    f   b
     ggg   
    e   c
    e   c
     ddd   
    
    */
    //.gfedcba
    0b00111111,             //0
    0b00000110,             //1
    0b01011011,             //2
    0b01001111,             //3
    0b01100110,             //4
    0b01101101,             //5
    0b01111101,             //6
    0b00000111,             //7
    0b01111111,             //8
    0b01101111,             //9
    0b01111111,             //10
    0b01111111,             //11
    0b01111111,             //12
    0b01111111,             //13
    0b01111111,             //14
    0b01111111              //15

};


unsigned int8 digit[2], dptr=0, dseg=1, scan_skip=0, beep=0, buz_pol=0;

#int_timer0
void tmr0_isr(void)
{
    set_timer0(255 - 155);  //4khz

    ++scan_skip;
    if (scan_skip>=4)
    {
        output_low(COM1_PIN);
        output_low(COM2_PIN);
        
        if (dptr==0)
        {
            output_c(~(dseg & digit[0]));
            output_high(COM1_PIN);
        }
        else
        {
            output_c(~(dseg & digit[1]));
            output_high(COM2_PIN);
        }
        
        dseg <<=1;
        if (dseg==0)
        {
            dseg = 1;
            dptr ^= 1;
        }
        scan_skip = 0;
    }
    
    if (beep)
    {
        buz_pol ^= 1;
        if (buz_pol)
        {
            output_high(BUZZERP_PIN);
            output_low(BUZZERN_PIN);
        }
        else
        {
            output_low(BUZZERP_PIN);
            output_high(BUZZERN_PIN);
        }
    }
}

void show_status(void)
{
    if (rx < 1.05)
    {
        output_high(PASS_PIN);
        beep = 1;
    }
    else if (rx < 5.05)
    {
        output_high(PASS_PIN);
        beep = 0;
    }
    else if (rx < 15.05)
    {
        output_high(PASS_PIN);
        delay_cycles(2);
        output_high(FAIL_PIN);
        beep = 0;
    }
    else
    {
        output_high(FAIL_PIN);
        beep = 0;
    }
}


void main(void)
{
    unsigned int16 vs, vo, vg;
    unsigned int8 i, c1, c2;
    
    port_b_pullups(0);
    set_tris_b(0x00);
    
    set_tris_c(0x00);
    output_c(0xFF);
    
    set_tris_a(0x01);
    output_a(0);

    setup_adc_ports(AN0);
    setup_adc(ADC_CLOCK_DIV_32);
    set_adc_channel(0);
    
    set_tris_b(0);
    
    setup_timer_0(RTCC_INTERNAL|RTCC_DIV_4);
    set_timer0(255 - 155);  //8khz
    enable_interrupts(INT_TIMER0);
    enable_interrupts(GLOBAL);

    i=0;

    for(;;)
    {
        output_b(0);
        delay_ms(20);
        vg = read_adc();

        output_b(CHARGE_MASK);
        delay_ms(20);
        vs = read_adc();
        delay_us(25);
        
        //critical part
        disable_interrupts(GLOBAL);
        output_b(DEBUG_MASK);
        //delay_us(1);
        vo = read_adc();
        enable_interrupts(GLOBAL);

        output_b(0);

        fvo = vo;
        fvs = vs;
        fvg = vg;
        
        fd = (fvg - fvo) + 0.00001;
        if (fd<=0.00001)
            fd = 0.00001;
        
        rx = ((r1 * (fvg - fvs))/fd) - r1 - r2;
        
        if (rx>=99.0)
        {
            digit[0] = led_map[9];
            digit[1] = led_map[9];
        }
        else if (rx<0)
        {
            digit[0] = led_map[0] | (1<<7);
            digit[1] = led_map[0];
        }
        else if (rx<10.0)
        {
            c1 = (rx + 0.05) * 10.0; //round
            c2 = c1 % 10;
            c1 -= c2;
            c1 /= 10;
            digit[0] = led_map[c1] | (1<<7);
            digit[1] = led_map[c2];
        }
        else
        {
            c1 = rx + 0.5;  //round
            c2 = c1 % 10;
            c1 -= c2;
            c1 /= 10;
            digit[0] = led_map[c1];
            digit[1] = led_map[c2];
        }
        show_status();
    }
}