/*

  lcd.c firmware for Distant Meter V1.0
  the sensor is simple reed switch with magnet tied
  to bycycle wheel. Optional 8-bit analog display for 
  user sensor.
    
  MC908QY4CP 16-pin MCU
  compiled with icc08
     
  Copyright (c) 2004 Wichit Sirichote

*/
 

#include <io908QY4.H>

#define one_revolution 157 // 2PIr, radius is 25cm 
#define p 1 // scale of ADC reading


char temp,k;
unsigned int PV,temp16;
char i,n,timer1,timer2;
unsigned char sec;
char x1,x2,x3;

long average,length, count;

char diff,old, now;

char *title = "DISTANCE METER 1";
char buffer[10];

/*   signal for lcd interface
   E       PTB1
   RS      PTB0
 
   D4      PTB4
   D5      PTB5
   D6      PTB6
   D7      PTB7
   
   D0-D3 and R/W# are tied to GND
*/

	
void delay(int j)
{ 
   unsigned int i; 
   for (i = 0; i < j; i++) 
   COPCTL = 0;   // clear COP otherwise the cpu itself will be reset 	  
} 

void pulseE()
{ 
    PTB |= 2; 
    delay(10);
	PTB &= ~2;   
} 
void LCDWI(char c)     /* write instruction to instruction register */ 
{ 
     temp = c;
	 PTB &= ~3;   // clear RS and E
	 PTB &= 0x0f; // clear high nibbel to low
	 c &= 0xf0; // prepare only high nibble
	 PTB |= c;
	 pulseE();
	 c = temp;
	 c <<=4;
	 PTB &= 0x0f;
	 PTB |= c;
	 pulseE();
	 delay(50);
}	 

void 
LCDWD(char c)    /* write data to data register */ 
{ 
    temp = c;
	PTB |= 1; // set bit RS
	PTB &= ~2; // clear bit E
    PTB &= 0x0f; // clear high nibbel to low
	c &= 0xf0; // prepare only high nibble
	PTB |= c; // mearge high nibble first
	pulseE();
	c = temp;
	c <<=4;
	PTB &= 0x0f;
	PTB |= c;
	pulseE();
	delay(50);
}	

void i_LCD() /* initialize LCD in accordance with Hitachi 44780 4-bit
mode */ 
{
    PTB &= ~3;	// clear RS and E
	PTB |= 0x30;
	pulseE(); 
    delay(200); 
    pulseE(); 
    delay(50); 
    pulseE(); 
    delay(50); 
    PTB &= 0x0f;
	PTB |= 0x20;
	pulseE(); 
    pulseE(); 
    pulseE(); 
    LCDWI(0x28); // set 4-bit bus, 1/16 line, 5*7 dots  
    LCDWI(0x0c); // display on/off on display,off cursor, no blink
    LCDWI(0x06); // entry mode DDRAM auto address increment 
    LCDWI(1);    // clear display  
    delay(50); 
} 

// print LCD text >8
// the 16x1 line LCD has two blocks start address!
void print_lcds(char *s)
{
    char i;
	LCDWI(1); // clear display
	LCDWI(0x80); // start at left most position
	for(i=0; i<8; i++)
	  LCDWD(*s++);
	  LCDWI(0xc0); // new address for position 9
	   for(i=0; i<8; i++)
	      LCDWD(*s++);
}		

char read_ADC()
{
 	 ADSCR = 0; // read channel 0 one time
	 while(!(ADSCR&0x80))
	 ;
	 return ADR;
}
// 3-point moving average (digital filtering)

long read_ADC_filter(){
   PV = read_ADC();
   x3 = x2;
   x2 = x1;
   x1 = PV;
   PV = (x1+x2+x3)/3;
   return PV;
}		 					 

int read_adc_scale(){ 
  long k;
  k = read_ADC_filter()*p;
  return k;
}


void print_dec(char d,unsigned int n)
{
   buffer[0] = n/10000+48;
   temp16 = n%10000;
   buffer[1] = temp16/1000+48;
   temp16 %=1000;
   buffer[2] = temp16/100+48;
   temp16 %=100;
   buffer[3] = temp16/10+48;
   buffer[4] = temp16%10+48;
   LCDWI(d);
   for(i=0; i<5; i++)
     LCDWD(buffer[i]);
}   
	 
void print_distant()
{
 	 if(++timer1>10)
	 {
	 timer1 = 0;
	 PTA ^= 2; // toggle PA1
	// count++; // test auto increment
	 length = count*one_revolution; // one revolution = 157cm
	 print_dec(0x80,length/100); // 100cm = 1m
	 LCDWD(' ');
	 LCDWD('m');
	 print_dec(0xc0,read_adc_scale());
	 }
}	 

void task_led()
{
    if(++timer2>50)
	{
	 timer2 =0;
     LCDWI(0xc7);
	 k^=1;
	 if (k) LCDWD('-');
	 else LCDWD('_');
	 }
}

// PTA2 input bit for reed swicth sensor
// detect rising edge
void detect_pulse_input()
{  
     now = PTA&4; // read only PTA2
	 diff = old-now;
	 if(diff>4) count++;
	  old = now;
}	  

void print_average()
{   
    average += count;
	average /= 2;
    print_dec(0xc0,average);
}	

void main()
{
 	// OCSTRIM = 0x81; // trim internal oscillator
 	 delay(1000); // powerup delay for LCD
	 n = k=0;
 	 count = 0;
	 average = 0;
	 
	 TMODH = 0x01;
	 TMODL = 0xf4;
	 TSC = 0x06; // run timer 
	 DDRA = ~0x1; // PA0 is ADC input
	 DDRB = 0xff; // port B is output port
	 PTB = 0; // clear port B
	 PTAPUE = ~0x81; // osc2 pin is PTA4 I/O 
	 ADCLK = 0x40; // ADC clock= fbus/4
	 i_LCD();
	 print_lcds(title);
	 delay(60000);
	 now = old = PTA&4;
	 LCDWI(1); // clear lcd
	 //asm(" cli"); //enable irq interrupt
	 	 
	for(;;)
	{
	 while(!(TSC&0x80))
	 ;
	 TSC &= ~0x80; // clear TOF
	// PTA ^= 2; // task running ~60Hz so the loop running is 120Hz or 1/120Hz 
	 task_led();
	 print_distant();
	 detect_pulse_input();
	 COPCTL = 0; // clear COP 	 
	 }
}