common/timer.c

   1 #include <avr/io.h>
   2 #include "timer.h"
   3
   4 #define BIT(n) (1<<(n))
   5
   6 static void timer_start(uint8_t num, uint32_t period)
   7 {
   8         uint8_t cs;
   9
  10         if(num==0)
  11         {
  12                 if(period<0x100)
  13                         cs = BIT(CS00);
  14                 else if(period<0x800)
  15                 {
  16                         cs = BIT(CS01);
  17                         period /= 8;
  18                 }
  19                 else if(period<0x4000)
  20                 {
  21                         cs = BIT(CS01) | BIT(CS00);
  22                         period /= 64;
  23                 }
  24                 else if(period<0x10000)
  25                 {
  26                         cs = BIT(CS02);
  27                         period /= 256;
  28                 }
  29                 else
  30                 {
  31                         cs = BIT(CS02) | BIT(CS00);
  32                         period /= 1024;
  33                         if(period>0xFF)
  34                                 period = 0xFF;
  35                 }
  36                 TCCR0A = BIT(WGM01);
  37                 TCCR0B = cs;
  38                 OCR0A = period;
  39                 TIMSK0 = BIT(OCIE0A);
  40         }
  41         else if(num==1)
  42         {
  43                 if(period<0x10000)
  44                         cs = BIT(CS10);
  45                 else if(period<0x80000)
  46                 {
  47                         cs = BIT(CS11);
  48                         period /= 8;
  49                 }
  50                 else if(period<0x400000)
  51                 {
  52                         cs = BIT(CS11) | BIT(CS10);
  53                         period /= 64;
  54                 }
  55                 else if(period<0x1000000)
  56                 {
  57                         cs = BIT(CS12);
  58                         period /= 256;
  59                 }
  60                 else
  61                 {
  62                         cs = BIT(CS12) | BIT(CS10);
  63                         period /= 1024;
  64                         if(period>0xFFFF)
  65                                 period = 0xFFFF;
  66                 }
  67                 TCCR1A = 0;
  68                 TCCR1B = BIT(WGM12) | cs;
  69                 OCR1AH = period>>8;
  70                 OCR1AL = period;
  71                 TIMSK1 = BIT(OCIE1A);
  72         }
  73         else if(num==2)
  74         {
  75                 if(period<0x100)
  76                         cs = BIT(CS20);
  77                 else if(period<0x800)
  78                 {
  79                         cs = BIT(CS21);
  80                         period /= 8;
  81                 }
  82                 else if(period<0x2000)
  83                 {
  84                         cs = BIT(CS21) | BIT(CS20);
  85                         period /= 32;
  86                 }
  87                 else if(period<0x4000)
  88                 {
  89                         cs = BIT(CS22);
  90                         period /= 64;
  91                 }
  92                 else if(period<0x8000)
  93                 {
  94                         cs = BIT(CS22) | BIT(CS20);
  95                         period /= 128;
  96                 }
  97                 else if(period<0x10000)
  98                 {
  99                         cs = BIT(CS22) | BIT(CS21);
 100                         period /= 256;
 101                 }
 102                 else
 103                 {
 104                         cs = BIT(CS22) | BIT(CS21) | BIT(CS20);
 105                         period /= 1024;
 106                         if(period>0xFF)
 107                                 period = 0xFF;
 108                 }
 109                 TCCR2A = BIT(WGM21);
 110                 TCCR2B = cs;
 111                 OCR2A = period;
 112                 TIMSK2 = BIT(OCIE2A);
 113         }
 114 }
 115
 116 void timer_start_hz(uint8_t num, uint32_t freq_p, uint8_t freq_q)
 117 {
 118         timer_start(num, F_CPU*freq_q/freq_p);
 119 }
 120
 121 void timer_start_us(uint8_t num, uint32_t us)
 122 {
 123         timer_start(num, F_CPU/1000000*us);
 124 }
 125
 126 void timer_stop(uint8_t num)
 127 {
 128         if(num==0)
 129         {
 130                 TCCR0B = 0;
 131                 TIMSK0 = 0;
 132         }
 133         else if(num==1)
 134         {
 135                 TCCR1B = 0;
 136                 TIMSK1 = 0;
 137         }
 138         else if(num==2)
 139         {
 140                 TCCR2B = 0;
 141                 TIMSK2 = 0;
 142         }
 143 }