diff options
Diffstat (limited to 'cpukit/score/cpu/avr/avr/wdt.h')
| -rw-r--r-- | cpukit/score/cpu/avr/avr/wdt.h | 248 |
1 files changed, 114 insertions, 134 deletions
diff --git a/cpukit/score/cpu/avr/avr/wdt.h b/cpukit/score/cpu/avr/avr/wdt.h index 0b424c9a83..7337e273b3 100644 --- a/cpukit/score/cpu/avr/avr/wdt.h +++ b/cpukit/score/cpu/avr/avr/wdt.h @@ -1,3 +1,8 @@ +/** + * @file + * + * @brief Watchdog Timer Handling + */ /* Copyright (c) 2002, 2004 Marek Michalkiewicz Copyright (c) 2005, 2006, 2007 Eric B. Weddington All rights reserved. @@ -40,59 +45,60 @@ #include <avr/io.h> #include <stdint.h> -/** \file */ -/** \defgroup avr_watchdog <avr/wdt.h>: Watchdog timer handling - \code #include <avr/wdt.h> \endcode - - This header file declares the interface to some inline macros - handling the watchdog timer present in many AVR devices. In order - to prevent the watchdog timer configuration from being - accidentally altered by a crashing application, a special timed - sequence is required in order to change it. The macros within - this header file handle the required sequence automatically - before changing any value. Interrupts will be disabled during - the manipulation. - - \note Depending on the fuse configuration of the particular - device, further restrictions might apply, in particular it might - be disallowed to turn off the watchdog timer. - - Note that for newer devices (ATmega88 and newer, effectively any - AVR that has the option to also generate interrupts), the watchdog - timer remains active even after a system reset (except a power-on - condition), using the fastest prescaler value (approximately 15 - ms). It is therefore required to turn off the watchdog early - during program startup, the datasheet recommends a sequence like - the following: - - \code - #include <stdint.h> - #include <avr/wdt.h> - - uint8_t mcusr_mirror __attribute__ ((section (".noinit"))); - - void get_mcusr(void) \ - __attribute__((naked)) \ - __attribute__((section(".init3"))); - void get_mcusr(void) - { - mcusr_mirror = MCUSR; - MCUSR = 0; - wdt_disable(); - } - \endcode - - Saving the value of MCUSR in \c mcusr_mirror is only needed if the - application later wants to examine the reset source, but in particular, - clearing the watchdog reset flag before disabling the - watchdog is required, according to the datasheet. +/** + * @defgroup avr_watchdog Watchdog Timer Handling + * + * This header file declares the interface to some inline macros + * handling the watchdog timer present in many AVR devices. In order + * to prevent the watchdog timer configuration from being + * accidentally altered by a crashing application, a special timed + * equence is required in order to change it. The macros within + * this header file handle the required sequence automatically + * before changing any value. Interrupts will be disabled during + * the manipulation. + * + * Note: Depending on the fuse configuration of the particular + * device, further restrictions might apply, in particular it might + * be disallowed to turn off the watchdog timer. + * + * Note that for newer devices (ATmega88 and newer, effectively any + * AVR that has the option to also generate interrupts), the watchdog + * timer remains active even after a system reset (except a power-on + * condition), using the fastest prescaler value (approximately 15 + * ms). It is therefore required to turn off the watchdog early + * during program startup, the datasheet recommends a sequence like + * the following: + * + * @code{.c} + * #include <stdint.h> + * #include <avr/wdt.h> + * + * uint8_t mcusr_mirror __attribute__ ((section (".noinit"))); + * + * void get_mcusr(void) \ + * __attribute__((naked)) \ + * __attribute__((section(".init3"))); + * void get_mcusr(void) + * { + * mcusr_mirror = MCUSR; + * MCUSR = 0; + * wdt_disable(); + * } + * @endcode + * + * Saving the value of MCUSR in @c mcusr_mirror is only needed if the + * application later wants to examine the reset source, but in particular, + * clearing the watchdog reset flag before disabling the + * watchdog is required, according to the datasheet. + * @{ */ /** - \ingroup avr_watchdog - Reset the watchdog timer. When the watchdog timer is enabled, - a call to this instruction is required before the timer expires, - otherwise a watchdog-initiated device reset will occur. + * @brief Watchdog Timer Reset + * + * Reset the watchdog timer. When the watchdog timer is enabled, + * a call to this instruction is required before the timer expires, + * otherwise a watchdog-initiated device reset will occur. */ #define wdt_reset() __asm__ __volatile__ ("wdr") @@ -118,14 +124,13 @@ /** - \ingroup avr_watchdog - Enable the watchdog timer, configuring it for expiry after - \c timeout (which is a combination of the \c WDP0 through - \c WDP2 bits to write into the \c WDTCR register; For those devices - that have a \c WDTCSR register, it uses the combination of the \c WDP0 - through \c WDP3 bits). - - See also the symbolic constants \c WDTO_15MS et al. + * Enable the watchdog timer, configuring it for expiry after + * @c timeout (which is a combination of the @c WDP0 through + * @c WDP2 bits to write into the @c WDTCR register; For those devices + * that have a @c WDTCSR register, it uses the combination of the @c WDP0 + * through @c WDP3 bits). + * + * See also the symbolic constants @c WDTO_15MS et al. */ @@ -317,10 +322,9 @@ __asm__ __volatile__ ( \ ) /** - \ingroup avr_watchdog - Disable the watchdog timer, if possible. This attempts to turn off the - Enable bit in the watchdog control register. See the datasheet for - details. + * Disable the watchdog timer, if possible. This attempts to turn off the + * Enable bit in the watchdog control register. See the datasheet for + * details. */ #define wdt_disable() \ __asm__ __volatile__ ( \ @@ -340,101 +344,77 @@ __asm__ __volatile__ ( \ /** - \ingroup avr_watchdog - Symbolic constants for the watchdog timeout. Since the watchdog - timer is based on a free-running RC oscillator, the times are - approximate only and apply to a supply voltage of 5 V. At lower - supply voltages, the times will increase. For older devices, the - times will be as large as three times when operating at Vcc = 3 V, - while the newer devices (e. g. ATmega128, ATmega8) only experience - a negligible change. - - Possible timeout values are: 15 ms, 30 ms, 60 ms, 120 ms, 250 ms, - 500 ms, 1 s, 2 s. (Some devices also allow for 4 s and 8 s.) - Symbolic constants are formed by the prefix - \c WDTO_, followed by the time. - - Example that would select a watchdog timer expiry of approximately - 500 ms: - \code - wdt_enable(WDTO_500MS); - \endcode + * Symbolic constants for the watchdog timeout. Since the watchdog + * timer is based on a free-running RC oscillator, the times are + * approximate only and apply to a supply voltage of 5 V. At lower + * supply voltages, the times will increase. For older devices, the + * times will be as large as three times when operating at Vcc = 3 V, + * while the newer devices (e. g. ATmega128, ATmega8) only experience + * a negligible change. + * + * Possible timeout values are: 15 ms, 30 ms, 60 ms, 120 ms, 250 ms, + * 500 ms, 1 s, 2 s. (Some devices also allow for 4 s and 8 s.) + * Symbolic constants are formed by the prefix + * @c WDTO_, followed by the time. + * + * Example that would select a watchdog timer expiry of approximately + * 500 ms: + * + * @code{.c} + * wdt_enable(WDTO_500MS); + * @endcode */ #define WDTO_15MS 0 -/** \ingroup avr_watchdog - See \c WDT0_15MS */ +/** @see WDT0_15MS */ #define WDTO_30MS 1 -/** \ingroup avr_watchdog See - \c WDT0_15MS */ +/** @see WDT0_15MS */ #define WDTO_60MS 2 -/** \ingroup avr_watchdog - See \c WDT0_15MS */ +/** @see WDT0_15MS */ #define WDTO_120MS 3 -/** \ingroup avr_watchdog - See \c WDT0_15MS */ +/** @see WDT0_15MS */ #define WDTO_250MS 4 -/** \ingroup avr_watchdog - See \c WDT0_15MS */ +/** @see WDT0_15MS */ #define WDTO_500MS 5 -/** \ingroup avr_watchdog - See \c WDT0_15MS */ +/** @see WDT0_15MS */ #define WDTO_1S 6 -/** \ingroup avr_watchdog - See \c WDT0_15MS */ +/** @see WDT0_15MS */ #define WDTO_2S 7 #if defined(__DOXYGEN__) || defined(WDP3) -/** \ingroup avr_watchdog - See \c WDT0_15MS - Note: This is only available on the - ATtiny2313, - ATtiny24, ATtiny44, ATtiny84, - ATtiny25, ATtiny45, ATtiny85, - ATtiny261, ATtiny461, ATtiny861, - ATmega48, ATmega88, ATmega168, - ATmega48P, ATmega88P, ATmega168P, ATmega328P, - ATmega164P, ATmega324P, ATmega644P, ATmega644, - ATmega640, ATmega1280, ATmega1281, ATmega2560, ATmega2561, - ATmega8HVA, ATmega16HVA, ATmega32HVB, - ATmega406, ATmega1284P, - AT90PWM1, AT90PWM2, AT90PWM2B, AT90PWM3, AT90PWM3B, AT90PWM216, AT90PWM316, - AT90PWM81, - AT90USB82, AT90USB162, - AT90USB646, AT90USB647, AT90USB1286, AT90USB1287, - ATtiny48, ATtiny88. - */ +/** + * @see WDT0_15MS + * + * Note: This is only available on: + * ATtiny2313, + * ATtiny24, ATtiny44, ATtiny84, + * ATtiny25, ATtiny45, ATtiny85, + * ATtiny261, ATtiny461, ATtiny861, + * ATmega48, ATmega88, ATmega168, + * ATmega48P, ATmega88P, ATmega168P, ATmega328P, + * ATmega164P, ATmega324P, ATmega644P, ATmega644, + * ATmega640, ATmega1280, ATmega1281, ATmega2560, ATmega2561, + * ATmega8HVA, ATmega16HVA, ATmega32HVB, + * ATmega406, ATmega1284P, + * AT90PWM1, AT90PWM2, AT90PWM2B, AT90PWM3, AT90PWM3B, AT90PWM216, AT90PWM316, + * AT90PWM81, + * AT90USB82, AT90USB162, + * AT90USB646, AT90USB647, AT90USB1286, AT90USB1287, + * ATtiny48, ATtiny88. + */ #define WDTO_4S 8 -/** \ingroup avr_watchdog - See \c WDT0_15MS - Note: This is only available on the - ATtiny2313, - ATtiny24, ATtiny44, ATtiny84, - ATtiny25, ATtiny45, ATtiny85, - ATtiny261, ATtiny461, ATtiny861, - ATmega48, ATmega88, ATmega168, - ATmega48P, ATmega88P, ATmega168P, ATmega328P, - ATmega164P, ATmega324P, ATmega644P, ATmega644, - ATmega640, ATmega1280, ATmega1281, ATmega2560, ATmega2561, - ATmega8HVA, ATmega16HVA, ATmega32HVB, - ATmega406, ATmega1284P, - AT90PWM1, AT90PWM2, AT90PWM2B, AT90PWM3, AT90PWM3B, AT90PWM216, AT90PWM316, - AT90PWM81, - AT90USB82, AT90USB162, - AT90USB646, AT90USB647, AT90USB1286, AT90USB1287, - ATtiny48, ATtiny88. - */ +/** @see WDTO_4S */ #define WDTO_8S 9 #endif /* defined(__DOXYGEN__) || defined(WDP3) */ - +/** @} */ #endif /* _AVR_WDT_H_ */ |