4 * Copyright 2003, 2004, 2005 Develer S.r.l. (http://www.develer.com/)
5 * Copyright 2000 Bernardo Innocenti <bernie@develer.com>
6 * This file is part of DevLib - See README.devlib for information.
11 * \author Bernardo Innocenti <bernie@develer.com>
12 * \author Francesco Sacchi <batt@develer.com>
14 * \brief Low-level timer module for AVR (interface).
19 *#* Revision 1.27 2006/05/18 00:38:24 bernie
20 *#* Use hw_cpu.h instead of ubiquitous hw.h.
22 *#* Revision 1.26 2006/02/21 21:28:02 bernie
23 *#* New time handling based on TIMER_TICKS_PER_SEC to support slow timers with ticks longer than 1ms.
25 *#* Revision 1.25 2005/07/19 07:26:37 bernie
26 *#* Refactor to decouple timer ticks from milliseconds.
28 *#* Revision 1.24 2005/04/11 19:10:28 bernie
29 *#* Include top-level headers from cfg/ subdir.
31 *#* Revision 1.23 2005/03/01 23:24:51 bernie
32 *#* Tweaks for avr-libc 1.2.x.
34 *#* Revision 1.21 2004/12/13 12:07:06 bernie
35 *#* DISABLE_IRQSAVE/ENABLE_IRQRESTORE: Convert to IRQ_SAVE_DISABLE/IRQ_RESTORE.
37 *#* Revision 1.20 2004/11/16 20:59:46 bernie
38 *#* Include <avr/io.h> explicitly.
40 *#* Revision 1.19 2004/10/19 08:56:41 bernie
41 *#* TIMER_STROBE_ON, TIMER_STROBE_OFF, TIMER_STROBE_INIT: Move from timer_avr.h to timer.h, where they really belong.
43 *#* Revision 1.18 2004/09/20 03:31:03 bernie
44 *#* Fix racy racy code.
46 #ifndef DRV_TIMER_AVR_H
47 #define DRV_TIMER_AVR_H
49 #include <appconfig.h> /* CONFIG_TIMER */
50 #include <cfg/compiler.h> /* uint8_t */
51 #include <hw_cpu.h> /* CLOCK_FREQ */
54 * \name Values for CONFIG_TIMER.
56 * Select which hardware timer interrupt to use for system clock and softtimers.
57 * \note The timer 1 overflow mode set the timer as a 24 kHz PWM.
61 #define TIMER_ON_OUTPUT_COMPARE0 1
62 #define TIMER_ON_OVERFLOW1 2
63 #define TIMER_ON_OUTPUT_COMPARE2 3
64 #define TIMER_ON_OVERFLOW3 4
68 * Hardware dependent timer initialization.
70 #if (CONFIG_TIMER == TIMER_ON_OUTPUT_COMPARE0)
72 #define TIMER_PRESCALER 64
73 #define TIMER_HW_BITS 8
74 #define DEFINE_TIMER_ISR SIGNAL(SIG_OUTPUT_COMPARE0)
75 #define TIMER_TICKS_PER_SEC 1000
76 #define TIMER_HW_CNT OCR_DIVISOR
78 //! Type of time expressed in ticks of the hardware high-precision timer
79 typedef uint8_t hptime_t;
81 #elif (CONFIG_TIMER == TIMER_ON_OVERFLOW1)
83 #define TIMER_PRESCALER 1
84 #define TIMER_HW_BITS 8
85 /*! This value is the maximum in overflow based timers. */
86 #define TIMER_HW_CNT (1 << TIMER_HW_BITS)
87 #define DEFINE_TIMER_ISR SIGNAL(SIG_OVERFLOW1)
88 #define TIMER_TICKS_PER_SEC ((TIMER_HW_HPTICKS_PER_SEC + TIMER_HW_CNT / 2) / TIMER_HW_CNT)
90 //! Type of time expressed in ticks of the hardware high precision timer
91 typedef uint16_t hptime_t;
93 #elif (CONFIG_TIMER == TIMER_ON_OUTPUT_COMPARE2)
95 #define TIMER_PRESCALER 64
96 #define TIMER_HW_BITS 8
97 #define DEFINE_TIMER_ISR SIGNAL(SIG_OUTPUT_COMPARE2)
98 #define TIMER_TICKS_PER_SEC 1000
99 /*! Value for OCR register in output-compare based timers. */
100 #define TIMER_HW_CNT OCR_DIVISOR
103 //! Type of time expressed in ticks of the hardware high precision timer
104 typedef uint8_t hptime_t;
106 #elif (CONFIG_TIMER == TIMER_ON_OVERFLOW3)
108 #define TIMER_PRESCALER 1
109 #define TIMER_HW_BITS 8
110 /*! This value is the maximum in overflow based timers. */
111 #define TIMER_HW_CNT (1 << TIMER_HW_BITS)
112 #define DEFINE_TIMER_ISR SIGNAL(SIG_OVERFLOW3)
113 #define TIMER_TICKS_PER_SEC ((TIMER_HW_HPTICKS_PER_SEC + TIMER_HW_CNT / 2) / TIMER_HW_CNT)
115 //! Type of time expressed in ticks of the hardware high precision timer
116 typedef uint16_t hptime_t;
119 #error Unimplemented value for CONFIG_TIMER
120 #endif /* CONFIG_TIMER */
123 /*! Frequency of the hardware high precision timer. */
124 #define TIMER_HW_HPTICKS_PER_SEC ((CLOCK_FREQ + TIMER_PRESCALER / 2) / TIMER_PRESCALER)
127 * System timer: additional division after the prescaler
128 * 12288000 / 64 / 192 (0..191) = 1 ms
130 #define OCR_DIVISOR (((CLOCK_FREQ + TIMER_PRESCALER / 2) / TIMER_PRESCALER + TIMER_TICKS_PER_SEC / 2) / TIMER_TICKS_PER_SEC - 1)
132 /*! Not needed, IRQ timer flag cleared automatically */
133 #define timer_hw_irq() do {} while (0)
136 #endif /* DRV_TIMER_AVR_H */