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timer_b.c

   1  /*******************************************************************************
   2     timerB.c:
   3     Copyright (C) 2009 Brno University of Technology,
   4                        Faculty of Information Technology
   5  
   6     LICENSE TERMS
   7  
   8     Redistribution and use in source and binary forms, with or without
   9     modification, are permitted provided that the following conditions
  10     are met:
  11     1. Redistributions of source code must retain the above copyright
  12        notice, this list of conditions and the following disclaimer.
  13     2. Redistributions in binary form must reproduce the above copyright
  14        notice, this list of conditions and the following disclaimer in
  15        the documentation and/or other materials provided with the
  16        distribution.
  17     3. All advertising materials mentioning features or use of this software
  18        or firmware must display the following acknowledgement:
  19  
  20          This product includes software developed by the University of
  21          Technology, Faculty of Information Technology, Brno and its
  22          contributors.
  23  
  24     4. Neither the name of the Company nor the names of its contributors
  25        may be used to endorse or promote products derived from this
  26        software without specific prior written permission.
  27  
  28     This software or firmware is provided ``as is'', and any express or implied
  29     warranties, including, but not limited to, the implied warranties of
  30     merchantability and fitness for a particular purpose are disclaimed.
  31     In no event shall the company or contributors be liable for any
  32     direct, indirect, incidental, special, exemplary, or consequential
  33     damages (including, but not limited to, procurement of substitute
  34     goods or services; loss of use, data, or profits; or business
  35     interruption) however caused and on any theory of liability, whether
  36     in contract, strict liability, or tort (including negligence or
  37     otherwise) arising in any way out of the use of this software, even
  38     if advised of the possibility of such damage.
  39  
  40     $Id$
  41  
  42  *******************************************************************************/
  43  
  44  #include "arch_specific.h"
  45  #include "define.h"
  46  #include "timer_b.h"
  47  
  48  /**
  49  
  50   **/
  51  void timerb_init(void) {
  52    // TimerB zvysi svou hodnotu kazdych 8/f_SMCLK sekund
  53    // 8 / 14.745 MHz = 0.5425us
  54  
  55    TBCTL  =  CNTL_0 | TBCLR | TBSSEL_2 | ID_2;      // nulovani casovace, halt, clock SMCLK, divider 4, 16bit counter
  56    TBCTL |=  MC_2;                                  // kontinualni mod, start timer
  57  }
  58  
  59  /**
  60  
  61  
  62   **/
  63  void delay_ms(unsigned long msecs) {
  64    unsigned long Pomdelay_cycle;
  65    unsigned int  FirstTBR;
  66    unsigned int  SecondTBR;
  67  
  68    msecs   = msecs * 1843;  // 1ms ~= 1843 * perioda casovace (1843 * 0.5425us)
  69    FirstTBR = TBR;
  70    Pomdelay_cycle = 0;
  71  
  72    while (Pomdelay_cycle < msecs)
  73    {
  74  
  75      WDG_reset();  //nulovani watchdogu
  76  
  77      SecondTBR = TBR;
  78      if (SecondTBR != FirstTBR)
  79      {
  80         if (SecondTBR > FirstTBR)
  81           Pomdelay_cycle = Pomdelay_cycle + (unsigned long)(SecondTBR - FirstTBR);
  82         else
  83           Pomdelay_cycle = Pomdelay_cycle + (unsigned long)((TBCCR0 - FirstTBR) + SecondTBR + 1);
  84  
  85         FirstTBR = SecondTBR;
  86      }
  87  
  88    }
  89  }
  90