#include <8052.h>

sfr at 0xD7 PLLCON;
sfr at 0xEF ADCCON1;
sfr at 0xD8 ADCCON2;

volatile int _n;

/* Timer 0 Interrupt Routine */
void ET0_int() interrupt 1
{
  _n--;
}

void wait(int w)
{
  int i;
  TH0 = 129;             // 16777216 / 12 / 127 / 110 = 100.08 Hz
  TL0 = 129;
  TR0 = 1;
  ET0 = 1;
  for (i = w; i > 0; i--) {
    _n = 110;
    while (_n > 0)
      ;
  }
  TR0 = 0;
  ET0 = 0;
}

void stop(int i)
{
  P3 = P3 | 0x3C;
  wait(i);
}

void forward(int i)
{
  P3 = P3 & 0xC3;
  P3 = P3 | 0x14;
  wait(i);
}

void back(int i)
{
  P3 = P3 & 0xC3;
  P3 = P3 | 0x28;
  wait(i);
}

void right(int i)
{
  P3 = P3 & 0xC3;
  P3 = P3 | 0x18;
  wait(i);
}

void left(int i)
{
  P3 = P3 & 0xC3;
  P3 = P3 | 0x24;
  wait(i);
}

void init(void)
{
  PLLCON = 0x00;         // core clock = 16.777216 MHz   
  SCON = 0x52;           // 8bit, no_parity, 1 stop_bit
  TMOD = 0x22;           // Timer1=8 bit_mode, Timer0=8 bit_mode
  TH1 = 0xF7;            // ..for 9600 baud..
  TR1 = 1;               // ..(assuming 16.777216 MHz clock)
  PCON = 0x80;           // double baud rate
  ADCCON1 = 0xAC;        // power up ADC & not EXT_Reference
  ADCCON2 = 0x00;        // sellect chan#0
  P1 = 0x03;             // Light OFF
  P3 = 0x03;             // all motor off
  /* interrupt enable */
  IE    = 0x80;
}


void main(void)
{
  init();
  forward(200);
  left(50);
  back(100);
  stop(0);
}