common/avr/timer_avr.h

   1 /*
   2 Copyright 2011 Jun Wako <wakojun@gmail.com>
   3
   4 This program is free software: you can redistribute it and/or modify
   5 it under the terms of the GNU General Public License as published by
   6 the Free Software Foundation, either version 2 of the License, or
   7 (at your option) any later version.
   8
   9 This program is distributed in the hope that it will be useful,
  10 but WITHOUT ANY WARRANTY; without even the implied warranty of
  11 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  12 GNU General Public License for more details.
  13
  14 You should have received a copy of the GNU General Public License
  15 along with this program.  If not, see <http://www.gnu.org/licenses/>.
  16 */
  17
  18 #ifndef TIMER_AVR_H
  19 #define TIMER_AVR_H 1
  20
  21 #include <stdint.h>
  22
  23 #ifndef TIMER_PRESCALER
  24 #   if F_CPU > 16000000
  25 #       define TIMER_PRESCALER      256
  26 #   elif F_CPU > 2000000
  27 #       define TIMER_PRESCALER      64
  28 #   elif F_CPU > 250000
  29 #       define TIMER_PRESCALER      8
  30 #   else
  31 #       define TIMER_PRESCALER      1
  32 #   endif
  33 #endif
  34 #define TIMER_RAW_FREQ      (F_CPU/TIMER_PRESCALER)
  35 #define TIMER_RAW           TCNT0
  36 #define TIMER_RAW_TOP       (TIMER_RAW_FREQ/1000)
  37
  38 #if (TIMER_RAW_TOP > 255)
  39 #   error "Timer0 can't count 1ms at this clock freq. Use larger prescaler."
  40 #endif
  41
  42 #endif