init_PCA()
{
    PCA0CN    = 0x40;
    PCA0MD    = 0x04;

}
void timer0_ISR (void) interrupt 1
{
TH0 = 0xFA;//1ms
TL0 = 0xCB;

    PCA0L     = 0xCB;
    PCA0H     = 0xFA;}

/* Function:    io_check_inputs
* Description: Check the input levels of all intrusions and write the changes if any.
* Parameter:   power_state_t power_state: use as indicator if the device is battery powered at the moment.
* Return:      intr_state_t intr_rc: status indicationg input changes:
*                  INTR_STATE_NOT_DETECTED: no input changes detected.
*                  INTR_STATE_RECHECK_DETECTED: a change detected but still not sure it is true. After 19ms will get decision!
*                  INTR_STATE_DETECTED: found changes in one or more inputs.
*/
intr_state_t io_check_inputs(uint8_t *online_status, const power_state_t power_state)
{
    static intr_state_t     intr_state;
    static uint8_t          timer1ms;
    intr_state_t            intr_rc;                        // Signal the caller about the intrusions check progress.
    static uint8_t          old_port[PORT_INDEX_MAX];       // The initial values - 0 - are equal to all doors closed (no intrusion).
    uint8_t                 new_port[PORT_INDEX_MAX];
    uint8_t                 u;

    intr_rc = INTR_STATE_NOT_DETECTED;                      // No change in any intrusion.

    io_read_inputs(new_port);

    switch (intr_state)
    {
        case INTR_STATE_NOT_DETECTED:
            if (memcmp(old_port, new_port, PORT_INDEX_MAX))
            {
                memcpy(old_port, new_port, PORT_INDEX_MAX);

                intr_state  = INTR_STATE_RECHECK_DETECTED;
                intr_rc     = INTR_STATE_RECHECK_DETECTED;
                timer1ms    = g_tmr0_tick1ms;
            }
            break;

        case INTR_STATE_RECHECK_DETECTED:
            intr_rc = INTR_STATE_RECHECK_DETECTED;          // The caller is informed that currently some intrusion is checking!
            u       = g_tmr0_tick1ms - timer1ms;

            if ((u > INTR_RECHECK_INTERVAL) || (POWER_STATE_OFFLINE == power_state))
            {
                intr_state = INTR_STATE_NOT_DETECTED;       // Ready to detect another intrusion.

                if (!memcmp(old_port, new_port, PORT_INDEX_MAX))
                {   // After the required delay the input levels are still the same - door is open/close.
                    intr_rc = INTR_STATE_DETECTED;
                    io_copy_inputs(online_status, new_port);
                }
            }
            break;
    }

    return intr_rc;
}