summaryrefslogtreecommitdiff
path: root/n/asserv/src/timer.c
blob: 1e18aca8decedfbab6b9b021abbc3812b3e580f9 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
/* timer.c */
/* asserv - Position & speed motor control on a ATmega128. {{{
 *
 * Copyright (C) 2004 Nicolas Schodet
 *
 * Robot APB Team/Efrei 2005.
 *        Web: http://assos.efrei.fr/robot/
 *      Email: robot AT efrei DOT fr
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 * 
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
 *
 * }}} */

/* +AutoDec */

/** Initialise the timer. */
static inline void
timer_init (void);

/** Test if a overflow occured and reset the flag. */
static inline int
timer_pending (void);

/** Read timer value. Used for performance analysis. */
static inline int8_t
timer_read (void);

/* -AutoDec */

/** Initialise the timer. */
static inline void
timer_init (void)
{
    /* 1024 prescaler. */
    TCCR0 = regv (FOC0, WGM00, COM01, COM0, WGM01, CS02, CS01, CS00,
		     0,     0,     0,    0,     0,    1,    1,    0);
    /* Fov = F_io / (prescaler * (TOP + 1))
     * Tov = 1 / Fov = 4.44 ms */
}

/** Test if a overflow occured and reset the flag. */
static inline int
timer_pending (void)
{
    if (TIFR & _BV (TOV0))
      {
	/* Write 1 to clear. */
	TIFR |= _BV (TOV0);
	return 1;
      }
    else
	return 0;
}

/** Read timer value. Used for performance analysis. */
static inline int8_t
timer_read (void)
{
    return TCNT0;
}