// 3-wire LCD test code for 24-pin PIC18F for the
// SDCC compiler (v3.2.0), July 7 2012 by WTN  (mod Sept 7 2015)
// Command line: sdcc -mpic16 -p18f2525 --use-non-free sdcc_lcd_test.c
// May be used for any purpose, provided as-is and without warranty.

#include <pic18fregs.h>
#include <stdio.h>
#include <stdlib.h>

#pragma config OSC=INTIO67,MCLRE=ON,WDT=OFF,PWRT=ON,BOREN=OFF,LVP=OFF,XINST=OFF

// bit macros
#define  testbit(var, bit)   ((var) & (1 <<(bit)))
#define  setbit(var, bit)    ((var) |= (1 << (bit)))
#define  clrbit(var, bit)    ((var) &= ~(1 << (bit)))

// RA0 = analog input 0
// RA1 = analog input 1
// RA2 = analog input 2
// RA3 = analog input 3
// RA4 = output LCD backlight default 0
// RA5 = analog input 4
// RB2 = analog input 8
// RB5 = output LCD E      default 0
// RB6 = output LCD CLK    default 0
// RB7 = output LCD DAT/RS default 0

#define portadirs 0b11101111
#define portbdirs 0b00011111
#define portcdirs 0b11111111
#define portadefaults 0b00000000
#define portbdefaults 0b00000000
#define portcdefaults 0b00000000

#define LCDbacklight LATAbits.LATA4
#define LCDenable    LATBbits.LATB5
#define LCDclock     LATBbits.LATB6
#define LCDdata      LATBbits.LATB7

// program declarations
int readanalog(unsigned char analog_channel);

// lcd code declarations
void loopdelay(unsigned int count);
void delayms(unsigned int ms);
// void putchar(char arg) __wparam; // already declared
void initLCD(void);
void setLCDshift(unsigned char c);
void sendLCDcommand(unsigned char c);
void sendLCDdata(unsigned char c);

// program variables
int analogvalue;
int var1;
float fvar1;
char buffer[10];

void main(void) {
    INTCON = 0;             // no interrupts
    OSCCON = 0b01110000;    // set for 8mhz clock
    ADCON1 = 0b00000110;    // use AN0-4,AN8, rest digital
    CMCON = 0;              // no comparators
    LATA = portadefaults;     // set default pin states
    LATB = portbdefaults;
    LATC = portcdefaults;
    TRISA = portadirs;         // set pin directions
    TRISB = portbdirs;
    TRISC = portcdirs;

    stdout = STREAM_USER;     // tell SDCC where to stream to

    initLCD();
    printf("Hello World");
    LCDbacklight = 1;         // flash backlight for approx 1 sec
    delayms(1000);            // use to calibrate mscalibrate define
    LCDbacklight = 0;         // leave off to save battery while debugging
    printf("\rNice to See");
    while(1) {
        analogvalue=readanalog(8);  // jitters too much
        analogvalue=0;              // discard 1st reading then
        for (var1=0;var1<32;var1++) { // average 32 readings
            analogvalue=analogvalue+readanalog(8);
        }
        analogvalue=analogvalue/32;
        putchar((char)160);  //position to line 2 char 13
        fvar1 = (float) analogvalue;
        fvar1 = fvar1 / 204.8; // fvar1 = voltage assuming 5V supply
//        printf("%3.1fV",fvar1 + 0.05);
// no float print by default... so fake it...
        fvar1 = fvar1 + 0.05; //rounding
        var1 = (int) fvar1;
        printf("%d.",var1);   //print int part
        var1 = (fvar1 - (int) var1) * 10;
        printf("%dV",var1);    //print 1st number after dp
        delayms(1000);
    }
}

int readanalog(unsigned char analog_channel) {
// read analog input, channel = 0 for AN0 etc
// does not set up port I/O, just reads
    int analog_value;
    ADCON0 = (int) analog_channel * 4 + 1;
    ADCON2bits.ADFM = 1; // right justified
    ADCON0bits.GO   = 1; // start conversion
    while (ADCON0bits.GO); // wait to complete
    analog_value = ADRESL;
    analog_value = analog_value + (ADRESH * 256);
    return analog_value;
}

// =========== LCD driver code ===========================================
// Created July 4 2012 by WTN (putchar modified for SDCC 7/7/12)
// For 3-wire LCD interface with 8-bit connection...
// define LCDenable to pin connected to E line
// define LCDdata to pin connected to shift reg data and RS line
// define LCDclock to shift reg clock pin (74HC164)
//
// Partial support for Parallax-like LCD commands...
// 8   move cursor left
// 9   move cursor right
// 12  clear screen
// 21  turn off display
// 22  turn on display (cursor off, blink off)
// 23  turn on display (cursor off, blink on)
// 24  turn on display (cursor on, blink off)
// 25  turn on display (cursor on, blink on)
// 128 position to 1st line (129-143 for chars 2-15)
// 148 position to 2nd line (149-163 for chars 2-15)
// 13  position to "next" line (alternates lines, does not clear)
// does not support line feed or other fancy stuff
// (Parallax is a trademark of the Parallax Inc. company,
//  who makes a serial LCD that implements similar commands.)
//
// Usage...
// initLCD();
// use printf to print strings
// use putchar to send command numbers
//
// Also supplies loopdelay(loops) and delayms(ms) subroutines
// set mscalibrate constant for number of loops for 1ms delay

unsigned char LCDcurrentline;  // global var for CR support
#define mscalibrate 270        // very approx for 8mhz clock

void loopdelay(unsigned int count)
{
    while(count--);
    return;
}

void delayms(unsigned int ms) {
    unsigned int i;
    for(i=0;i<ms;i++) {
        loopdelay(mscalibrate);
    }
    return;
}

void putchar(char arg) __wparam { // adapted for SDCC
    unsigned char c;
    unsigned char numberofshifts;
    c = (unsigned char) arg;
    if (c==13) {                 //cr code...
        if (LCDcurrentline == 0) {
            sendLCDcommand(192);
            LCDcurrentline = 1;
        } else {
            sendLCDcommand(128);
            LCDcurrentline = 0;
        }
    }
    else if (c==12) {            //12 = clear display
        sendLCDcommand(1);
        LCDcurrentline = 0;
    }
    else if (c==8) sendLCDcommand(0b00010000);    //8 = cursor left
    else if (c==9) sendLCDcommand(0b00010100);    //9 = cursor right
    else if (c==21) sendLCDcommand(0b00001000);   //21 = turn off display
    else if (c==22) sendLCDcommand(0b00001100);   //22 = turn on display
    else if (c==23) sendLCDcommand(0b00001101);   //23 = cursor off blink on
    else if (c==24) sendLCDcommand(0b00001110);   //24 = cursor on blink off
    else if (c==25) sendLCDcommand(0b00001111);   //25 = cursor on blink on
    else if (c>127) {
        if (c<148) {  //positions on 1st line 128-143
            sendLCDcommand(128);
            LCDcurrentline = 0;
            numberofshifts=c-128;
            while (numberofshifts) {
                sendLCDcommand(0b00010100);
                numberofshifts--;
            }
        } else {      //positions on 2nd line 148-163
            sendLCDcommand(192);
            LCDcurrentline = 1;
            numberofshifts=c-148;
            while (numberofshifts) {
                sendLCDcommand(0b00010100);
                numberofshifts--;
            }
        }
    }
    else sendLCDdata(c);
    return;
}

void initLCD(void) {
    setLCDshift(0);
    LCDenable=1;
    delayms(50);
    LCDenable=0;
    sendLCDcommand(0b00111000);
    delayms(10);
    sendLCDcommand(0b00111000);
    delayms(10);
    sendLCDcommand(0b00111000);
    delayms(10);
    sendLCDcommand(0b00111000);
    delayms(10);
    sendLCDcommand(0b00000100);
    sendLCDcommand(0b00001100);
    sendLCDcommand(0b00000001);
    LCDcurrentline = 0;
    return;
}

void setLCDshift(unsigned char c) {
    int i;
    LCDclock = 0;
    for (i=0;i<8;i++) {
        if (c & 0x80) LCDdata = 1; else LCDdata = 0;
        c = c << 1;
        LCDclock = 1;
        loopdelay(1);
        LCDclock = 0;
    }
    return;
}

void sendLCDcommand(unsigned char c) {
    setLCDshift(c);
    LCDdata=0;
    LCDenable=1;
    loopdelay(1);
    LCDenable=0;
    delayms(3);
    return;
}

void sendLCDdata(unsigned char c) {
    setLCDshift(c);
    LCDdata=1;
    LCDenable=1;
    loopdelay(1);
    LCDenable=0;
    delayms(3);
    return;
}
// ===== end LCD driver code =====
// end LCD test program