/*This is a programme for the demo of RTX51*/
 
#include <at89x51.h>    /* special function registers 8052 */
#include <intrins.h>
#include <rtx51tny.h>    /* RTX-51 tiny functions & defines */

/*Constants*/
#define INIT   0   /* task number of task:  init  */
#define SCAN_KEY  1   /* task number of task:  scanKey */
#define DEBOUNCE  2   /* task number of task:  debounce */
#define KEY_PROCESS  3   /* task number of task:  keyProcess */
#define DISPLAY   4   /* task number of task:  display */

/* Variables of Bytes */
unsigned char keyNumber;
unsigned char keyValue;
unsigned char keyTemp[5];
unsigned char keyInput[5];
unsigned char keyStore[5];
unsigned char keyReady[5];
unsigned char keyOutput[5];

/*Constant Data*/
code unsigned char keyCode[]=
 {0xa1,0xa2,0xa3,0xa4,0xa5,0xa6,0xa7,0xa8,
 0xb1,0xb2,0xb3,0xb4,0xb5,0xb6,0xb7,0xb8,
 0xc1,0xc2,0xc3,0xc4,0xc5,0xc6,0xc7,0xc8,
 0xd1,0xd2,0xd3,0xd4,0xd5,0xd6,0xd7,0xd8};

/*Bit Addressable of Ports and Register*/
unsigned char bdata led_buffer;
sbit led1 = led_buffer^0;
sbit led2 = led_buffer^1;
sbit led3 = led_buffer^2;
sbit led4 = led_buffer^3;
sbit acc_7 = ACC^7;

/*Function Prototypes*/
void serialInit (void);
unsigned char *getKeyValue (void);

/*Task 0 'init': Initialize*/
void init (void) _task_ INIT  /* program execution starts here */ 
{
  serialInit ();     /* initialize the serial interface */
  os_create_task (SCAN_KEY);  /* start scanKey task    */
  os_create_task (DISPLAY);   /* start display task    */
  os_delete_task (INIT);   /* stop init task (no longer needed)*/
  led_buffer = 0xff;    /* turn off all leds at the start */
}

/*Task 1 'scanKey'*/
void scanKey (void)  _task_ SCAN_KEY
{
  unsigned char i;
  unsigned char temp;

  while (1)       /* scanKey is an endless loop  */ 
  {

 P2 = temp = 0xfe;    /* set the first scan bit   */
 for (i = 0; i < 4; i++)  
      {
  keyInput[i] = ~P0;   /* have reversed data from P1  */
  P2 = P2 | ~temp;         /* reset the scan bit    */
  if (i == 3) break;   /* end last loop early    */
  temp = (temp << 1) + 1;  /* scan bit shift left    */
     P2 = P2 & temp;    /* set new scan bit     */ 
   }
 os_create_task (DEBOUNCE);  /* start debounce task    */
 os_wait (K_IVL, 2, 0);   /* wait interval: 20mS    */
  }
}

/*Task 2 'debounce'*/
void debounce (void)  _task_ DEBOUNCE
{
  unsigned char i;

  for (i = 0; i < 4; i++)
  {
 keyReady[i] = keyTemp[i] & keyInput[i] | keyReady[i]
      & (keyTemp[i] ^ keyInput[i]);
 keyTemp[i] = keyInput[i];

 keyOutput[i] = keyReady[i] & ~keyStore[i];
 keyStore[i] = keyReady[i];
  }
 
  if (keyOutput[0] | keyOutput[1] | keyOutput[2]
 | keyOutput[3] | keyOutput[4])
 os_create_task (KEY_PROCESS); /* start keyProcess task  */

  os_delete_task (DEBOUNCE);  /* stop debounce task   */
}

/*Task 3 'keyProcess'*/
void keyProcess (void)  _task_ KEY_PROCESS
{
  unsigned char *pointer;

  pointer = getKeyValue();
  keyValue = *pointer;
  SBUF = keyValue;     /* send the key Value to host */

  os_delete_task (KEY_PROCESS);  /* stop debounce task   */
}

/*Task 4 'display'*/
void display (void)  _task_ DISPLAY
{
  while (1)       /* dispaly is an endless loop  */ 
  {
 os_wait (K_SIG, 0, 0);   /* wait a signal     */

 if (led1) P1_0 = 0;else P1_0 = 1;/*turn on/off led 1    */
 if (led2) P1_1 = 0;else P1_1 = 1;/*turn on/off led 2    */
 if (led3) P1_2 = 0;else P1_2 = 1;/*turn on/off led 3    */
 if (led4) P1_3 = 0;else P1_3 = 1;/*turn on/off led 4    */
  }
}

/*Function 'getKeyValue'*/
unsigned char *getKeyValue (void)
{
  unsigned char temp;
  unsigned char i;
  unsigned char j;
  unsigned char *pointer = keyCode;

  for (i = 0; i < 4; i++)
  {
 for (j = 0; j < 8; j++)
 {
   temp = _cror_(keyOutput[i], 1);/* rotate right for pressed key */
   if (_testbit_(acc_7))   /* find pressed key if acc_7=1  */
   {
  keyNumber = 4 * j + i;  /* calculate the key order number */

  return(pointer + keyNumber);  
   }
   else keyOutput[i] = temp;  /* prepare for rotate next   */
 }
  }
}

/*serialInit: Initialize Ierial Interface*/
void serialInit (void) 
{
  SCON  = 0x50;                      /* mode 1:8bit UART,};enable receiver*/
  TMOD |= 0x20;                      /* timer 1 mode 2: 8-Bit reload */
  TH1   = 0xe8;                      /* reload value 1200 baud   */
  TR1   = 1;                         /* timer 1 run      */
  ES    = 1;                         /* enable serial port interrupt */
}

/*Serial Port Interrupt Handler*/
void serial_i_o_interrupt_handler(void) interrupt 4 using 2
{
    if (RI)
    {
  led_buffer = SBUF;   /* keep received led on/off data */
  RI = 0;                  /* clear receive interrupt flag  */
  isr_send_signal (DISPLAY); /* signal task display    */
  }

    TI = 0;       /* clear transmit interrupt flag  */
}

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