main.c

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// This file has been prepared for Doxygen automatic documentation generation.
#include <inavr.h>

#include <iotiny24.h>   // standard IAR header file with 4.11A and later
#include "main.h"
#include "USI_TWI_Master.h"
#include "LCD.h"
#include "KPD.h"

__flash unsigned char STRING_WELCOME[] = {"Tiny24 CODE LOCK"};
__flash unsigned char STRING_OPEN[] = {"   LOCK  OPEN   "};
__flash unsigned char STRING_CLOSE[] = {"  LOCK  CLOSED  "};

__eeprom unsigned char CODE_ACCESS[CODE_ACCESS_LENGTH+1] = {"1234 "};

unsigned char KeyBuffer[CODE_MAX_LENGTH];

// Main program
void main(void)
{
  unsigned char i;

  Initialise();

  Beep(625);                        // 800 Hz tone at 1 MHz clock
  Delay(100);
  LCD_ClearDisplay();
  ClearInputBuffer();
  Beep(0);

  do                                  // main loop
  {
    for (i=0;i<16;i++)
      LCD_PutXY(STRING_WELCOME[i],i,0); // uses less SRAM than LCD_WriteLine

    while (!KPD_KeyPressed);
    asm("wdr");                       // we have input; reset watchdog

    for (i=CODE_MAX_LENGTH;i>0;i--)
      KeyBuffer[i] = KeyBuffer[i-1];  // scroll input buffer
    KeyBuffer[0] = KPD_GetKey();
    Beep(625);                        // 800 Hz tone at 1 MHz clock
    Delay(100);
    Beep(0);

    for (i=0;i<CODE_MAX_LENGTH;i++)
      LCD_PutXY(KeyBuffer[i],11-i,1);

    CheckAccess();
  }
  while(1);
}

// Master init
void Initialise(void)
{
  USI_TWI_Master_Initialise();        // initialise TWI
  LCD_Init();                         // initialise LCD
  KPD_Init();                         // initialise keypad

  DDRA |= (1 << LOCK_PIN);            // set pin as output (lock control)
  PORTA &= ~(1 << LOCK_PIN);          // set pin low (close lock)

  DDRA |= (1 << PINA5);               // set pin A5 as output (buzzer)

  asm("wdr");
  MCUSR = 0;                          // clear all reset flags
  WDTCSR = (1<<WDIE) | (1<<WDE) | (1<<WDP3);  // enable WD, timeout in 4.0 s
}

void ClearInputBuffer(void)
{
  unsigned char i;

  for (i=0;i<CODE_MAX_LENGTH;i++)
    KeyBuffer[i] = 0;
}

void CheckAccess(void)
{
  unsigned char i;

  for (i=0;i<CODE_ACCESS_LENGTH;i++)
    if (CODE_ACCESS[CODE_ACCESS_LENGTH-i-1] != KeyBuffer[i])
      return;

  // Still here? It was a match, then. Sesame, open.
  OpenLock();
  for (i=0;i<16;i++)
    LCD_PutXY(STRING_CLOSE[i],i,0);   // uses less SRAM than LCD_WriteLine
  Delay(1000);
  KPD_Init();                         // initialise keypad: clear pending keys
}

// Activate signal, which opens the lock.
void OpenLock(void)
{
  unsigned char i;

  for (i=0;i<16;i++)
    LCD_PutXY(STRING_OPEN[i],i,0);    // uses less SRAM than LCD_WriteLine

  Beep(1250);                       // 400 Hz tone at 1 MHz clock

  PORTA |= (1 << LOCK_PIN);           // set pin high (open lock)
  DelayBar(3);
  PORTA &= ~(1 << LOCK_PIN);          // set pin low (close lock)

  Beep(0);
}

// Display a progress bar on second row of LCD. Reduce size of bar from right
// to left, one pixel at a time. Maximum time is 20 seconds (set by input).
void DelayBar(unsigned char sec)
{
  unsigned char i,j;
  unsigned char delay;

  delay = (sec << 2);
  delay += (sec << 3);
  delay += (sec / 2);

  for (i=0;i<16;i++)
    LCD_PutXY_Raw(0x13,i,1);
  for (i=0;i<16;i++)
  {
    for (j=0;j<4;j++)
    {
      LCD_PutXY_Raw(0x7E-j,15-i,1);
      Delay(delay);
    }
    LCD_PutXY(' ',15-i,1);
    Delay(delay);
  }
}

// Sound pietzoelectric buzzer using timer/counter 1. Buzzer frequency is
// inversely proportional to tone input value: Freq = fCLK / (2 x tone).
void Beep(unsigned int tone)
{
  if (tone == 0)
  {
    TCCR1A = (1 << COM1B1);               // clear OC1B on compare match
    TCCR1B = (1 << WGM12);                // CTC mode,  no clock
    TCCR1C = (1 << FOC1B);                // force output compare for channel B
  }
  else
  {
    TCNT1 = 0x0000;                       // clear 16-bit counter
    OCR1A = tone;                         // set TOP
    OCR1B = tone >> 1;                    // set compare
    TCCR1A = (1 << COM1B0);               // toggle OC1B on compare match
    TCCR1B = (1 << WGM12) | (1 << CS10);  // CTC mode, 1/CLK
  }
}

// Delay execution for number of milliseconds. Calibrated for 1 MHz clock.
void Delay(unsigned int ms)
{
  unsigned char delay;

  do
  {
    delay = 166;                      // 6 cycles/loop
    while(delay--);
  }
  while (ms--);
}

// Watchdog timeout.
#pragma vector = WDT_vect
__interrupt void WDT_ISR(void)
{
  MCUSR &= ~(1 << WDRF);              // clear WD reset flag
  WDTCSR |= (1<<WDIE);                // set WDIE to avoid hardware reset
  ClearInputBuffer();                 // erase all keystrokes from buffer
  LCD_ClearLine(1);                   // erase all characters on 2nd row
}

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