/*--    LCD 

         v1.5 - non ASCII for command entry
         v1.4 - better timing

                microproccesssor pins
                     ----
               RST -|    |- VCC    		 
          RX  P3_0 -| 2  |- P1_7   D7		 
          TX  P3_1 -| 0  |- P1_6   D6		 
              XTAL -| 5  |- P1_5   D5		 
              XTAL -| 1  |- P1_4   D4		 
              P3_2 -|    |- P1_3   D3		 
     E        P3_3 -|    |- P1_2   D2		 
    RS        P3_4 -|    |- P1_1 * D1		 
    RW        P3_5 -|    |- P1_0 * D0		 
               GND -|    |- P3_7		 
    		     ----			 

LCD pins
						       
1    ground					       
2    Vcc					       
3    contrast							
4    RS
5    RW				
6    E							
7    D0
8    D1
9    D2
10   D3
11   D4
12   D5
13   D6
14   D7
       					
--*/

#include "reg.h"
#include <stdio.h>
#define DATA P1
#define RS P3_4
#define RW P3_5
#define E  P3_3
#define LCD_FUNCTION_CODE 0x38  // 1 line:30, 2 lines:38

void pause(int);           // select pause in milliseconds
void loop(int);            // pauses 9us per count
void serial_init(void);    //  
void lcd_init(void);       //
void lcd_command(char);    //
void lcd_send(char);       //
char gethex2(void);        // 
void sendhex2(char);       //

/*----------------------------------*/

main(){

char a;

serial_init(); lcd_init();
lcd_send('V'); lcd_send('1'); lcd_send('.'); lcd_send('5');
	
while(1){
	putchar(':');
	a=_getkey();

      	switch (a) {  
		case 0x1B:  //ESC, to enter a command from the keyboard
    		putchar('\n'); putchar('*'); a=gethex2(); lcd_command(a); 
                break;

                case 0x03:  //ctrl C
    		a=_getkey(); lcd_command(a); 
                break;

                case 0x08:  //backspace
		lcd_command(0x10); lcd_send(' '); lcd_command(0x10);
                break;

		case 0x0D:  //return, home
		lcd_command(0x02); break;

		case 0x18:  // ctrl X, clear screen
		lcd_command(0x01); break;

		case 0x0A:  // second line
		lcd_command(0xc0); break;

		case 0x12:  // ctrl R, read data
               	RS=1; RW=1; E=1; a=DATA; E=0; sendhex2(a);
		pause(2); break;
                
		case 0x11:  // ctrl Q, read busy flag and address
        	RS=0; RW=1; E=1; a=DATA; E=0; sendhex2(a);
		pause(2); break;

		default:
		putchar(a); lcd_send(a); break;
       
	}

} //while


} //main

/*----------------------------*/
 void pause(int ms)
 {
        int n;
        while(ms!=0){
                n=125;
                while(n!=0){
                        n=n-1;
                }
                ms=ms-1;
        }
 }

/*---------------------------*/

void serial_init(void){
  SM0=0; SM1=1; SM2=1; REN=1;
  SCON  = 0x50;                 /* SCON: mode 1, 8-bit UART, enable rcvr    */
  TMOD &= 0x0f; TMOD |= 0x20;   /* TMOD: timer 1, mode 2, 8-bit reload      */

  TH1   = 0xfd;                 /* TH1:  reload value for 9600 baud         */
//TH1   = 0xfa;                 /* TH1:  reload value for 4800 baud         */
//TH1   = 0xf4;                 /* TH1:  reload value for 2400 baud         */

  TR1   = 1;                    /* TR1:  timer 1 run                        */
  TI    = 1;                    /* TI:   set TI to send first char of UART  */
return;
}
 
/*----------------------------*/

void lcd_init(void){

pause(1000);
E=0; 
lcd_command(LCD_FUNCTION_CODE);
lcd_command(LCD_FUNCTION_CODE); 
lcd_command(LCD_FUNCTION_CODE);                
lcd_command(0x06); 
lcd_command(0x0E); 
}

/*-------------------------------*/

void lcd_command(char a)
{
       	RS=0; RW=0; DATA=a; E=1; E=0;
        loop(190);  // creates more than the needed 1.64ms delay
       	return;
}

/*-----------------------------*/

void lcd_send(char a)
{
	RS=1; RW=0; DATA=a; E=1; E=0;
	loop(5);  // creates more than the needed 40us delay
        return;
}

/*-------------------------------*/

char gethex2(void)
{
	char a, high, low;
first:
	high = _getkey();
	if(high > 0x66)  {goto first;}
	if(high >= 0x61) {putchar(high); high=high-0x57; goto second;}
        if(high > 0x39)  {goto first;}
	if(high >= 0x30) {putchar(high); high=high-0x30; goto second;}
        goto first;

second:
      	low = _getkey();
	if(low > 0x66)  {goto second;}
	if(low >= 0x61) {putchar(low); low=low-0x57; goto join;}
        if(low > 0x39)  {goto second;}
	if(low >= 0x30) {putchar(low); low=low-0x30; goto join;}
        goto second;
join:
   	a=high*16+low;
	return a;
}

/*--------------------------------*/

void sendhex2(char a)
{
char high, low;

high = a/16 + 0x30; low = a%16 + 0x30; 
if(high > 0x39) {high = high + 0x27;}
if(low > 0x39) {low = low + 0x27;}
putchar(high); putchar(low);
return;
}

/*----------------------------------*/

// creates a time delay of about 9us per count

void loop (int n)
{
  while(n != 0){n=n-1;}
  return;                      
}