kopia lustrzana https://github.com/bristol-seds/pico-tracker
222 wiersze
8.6 KiB
C
222 wiersze
8.6 KiB
C
/**
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* SAM D20/D21/R21 Watchdog Driver
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*
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* Copyright (C) 2012-2014 Atmel Corporation. All rights reserved.
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*
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* \asf_license_start
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*
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* \page License
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions are met:
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*
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* 1. Redistributions of source code must retain the above copyright notice,
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* this list of conditions and the following disclaimer.
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*
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* 2. Redistributions in binary form must reproduce the above copyright notice,
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* this list of conditions and the following disclaimer in the documentation
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* and/or other materials provided with the distribution.
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*
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* 3. The name of Atmel may not be used to endorse or promote products derived
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* from this software without specific prior written permission.
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*
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* 4. This software may only be redistributed and used in connection with an
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* Atmel microcontroller product.
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*
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* THIS SOFTWARE IS PROVIDED BY ATMEL "AS IS" AND ANY EXPRESS OR IMPLIED
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* WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
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* MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NON-INFRINGEMENT ARE
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* EXPRESSLY AND SPECIFICALLY DISCLAIMED. IN NO EVENT SHALL ATMEL BE LIABLE FOR
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* ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
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* STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
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* ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
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* POSSIBILITY OF SUCH DAMAGE.
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*
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* \asf_license_stop
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*
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*/
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#ifndef WDT_H_INCLUDED
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#define WDT_H_INCLUDED
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/**
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* SAM D20/D21/R21 Watchdog Driver (WDT)
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*
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* This driver for SAM D20/D21/R21 devices provides an interface for
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* the configuration and management of the device's Watchdog Timer
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* module, including the enabling, disabling and kicking within the
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* device. The following driver API modes are covered by this manual:
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*
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* - Polled APIs
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*
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* The following peripherals are used by this module:
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*
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* - WDT (Watchdog Timer)
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*
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* Module Overview
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*
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* The Watchdog module (WDT) is designed to give an added level of
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* safety in critical systems, to ensure a system reset is triggered
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* in the case of a deadlock or other software malfunction that
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* prevents normal device operation.
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*
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* At a basic level, the Watchdog is a system timer with a fixed
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* period; once enabled, it will continue to count ticks of its
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* asynchronous clock until it is periodically reset, or the timeout
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* period is reached. In the event of a Watchdog timeout, the module
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* will trigger a system reset identical to a pulse of the device's
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* reset pin, resetting all peripherals to their power-on default
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* states and restarting the application software from the reset
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* vector.
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*
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* In many systems, there is an obvious upper bound to the amount of
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* time each iteration of the main application loop can be expected to
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* run, before a malfunction can be assumed (either due to a deadlock
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* waiting on hardware or software, or due to other means). When the
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* Watchdog is configured with a timeout period equal to this upper
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* bound, a malfunction in the system will force a full system reset
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* to allow for a graceful recovery.
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*
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* Locked Mode
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*
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* The Watchdog configuration can be set in the device fuses and
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* locked in hardware, so that no software changes can be made to the
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* Watchdog configuration. Additionally, the Watchdog can be locked on
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* in software if it is not already locked, so that the module
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* configuration cannot be modified until a power on reset of the
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* device.
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*
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* The locked configuration can be used to ensure that faulty software
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* does not cause the Watchdog configuration to be changed, preserving
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* the level of safety given by the module.
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*
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* Window Mode
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*
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* Just as there is a reasonable upper bound to the time the main
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* program loop should take for each iteration, there is also in many
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* applications a lower bound, i.e. a minimum time for which each loop
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* iteration should run for under normal circumstances. To guard
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* against a system failure resetting the Watchdog in a tight loop (or
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* a failure in the system application causing the main loop to run
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* faster than expected) a "Window" mode can be enabled to disallow
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* resetting of the Watchdog counter before a certain period of time.
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* If the Watchdog is not reset after the window opens but not before
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* the Watchdog expires, the system will reset.
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*
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* Early Warning
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*
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* In some cases it is desirable to receive an early warning that the
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* Watchdog is about to expire, so that some system action (such as
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* saving any system configuration data for failure analysis purposes)
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* can be performed before the system reset occurs. The Early Warning
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* feature of the Watchdog module allows such a notification to be
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* requested; after the configured early warning time (but before the
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* expiry of the Watchdog counter) the Early Warning flag will become
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* set, so that the user application can take an appropriate action.
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*
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* \note It is important to note that the purpose of the Early Warning feature
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* is not to allow the user application to reset the Watchdog; doing
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* so will defeat the safety the module gives to the user application.
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* Instead, this feature should be used purely to perform any tasks that
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* need to be undertaken before the system reset occurs.
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*
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* Special Considerations
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*
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* On some devices the Watchdog configuration can be fused to be always on in
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* a particular configuration; if this mode is enabled the Watchdog is not
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* software configurable and can have its count reset and early warning state
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* checked/cleared only.
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*
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*/
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#include "system/clock.h"
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#include "system/gclk.h"
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/**
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* Enum for the possible period settings of the Watchdog timer module, for
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* values requiring a period as a number of Watchdog timer clock ticks.
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*/
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enum wdt_period {
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/** No Watchdog period. This value can only be used when setting the
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* Window and Early Warning periods; its use as the Watchdog Reset
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* Period is invalid. */
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WDT_PERIOD_NONE = 0,
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/** Watchdog period of 8 clocks of the Watchdog Timer Generic Clock. */
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WDT_PERIOD_8CLK = 1,
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/** Watchdog period of 16 clocks of the Watchdog Timer Generic Clock. */
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WDT_PERIOD_16CLK = 2,
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/** Watchdog period of 32 clocks of the Watchdog Timer Generic Clock. */
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WDT_PERIOD_32CLK = 3,
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/** Watchdog period of 64 clocks of the Watchdog Timer Generic Clock. */
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WDT_PERIOD_64CLK = 4,
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/** Watchdog period of 128 clocks of the Watchdog Timer Generic Clock. */
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WDT_PERIOD_128CLK = 5,
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/** Watchdog period of 256 clocks of the Watchdog Timer Generic Clock. */
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WDT_PERIOD_256CLK = 6,
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/** Watchdog period of 512 clocks of the Watchdog Timer Generic Clock. */
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WDT_PERIOD_512CLK = 7,
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/** Watchdog period of 1024 clocks of the Watchdog Timer Generic Clock. */
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WDT_PERIOD_1024CLK = 8,
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/** Watchdog period of 2048 clocks of the Watchdog Timer Generic Clock. */
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WDT_PERIOD_2048CLK = 9,
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/** Watchdog period of 4096 clocks of the Watchdog Timer Generic Clock. */
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WDT_PERIOD_4096CLK = 10,
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/** Watchdog period of 8192 clocks of the Watchdog Timer Generic Clock. */
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WDT_PERIOD_8192CLK = 11,
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/** Watchdog period of 16384 clocks of the Watchdog Timer Generic Clock. */
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WDT_PERIOD_16384CLK = 12,
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};
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void wdt_set_config(bool always_on,
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bool enable,
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enum gclk_generator clock_source,
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enum wdt_period timeout_period,
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enum wdt_period window_period,
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enum wdt_period early_warning_period);
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void wdt_set_config_default(void);
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/**
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* Determines if the Watchdog timer is currently enabled and locked, so that
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* it cannot be disabled or otherwise reconfigured.
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*
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* \return Current Watchdog lock state.
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*/
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static inline bool wdt_is_locked(void)
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{
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Wdt *const WDT_module = WDT;
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return (WDT_module->CTRL.reg & WDT_CTRL_ALWAYSON);
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}
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/**
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* Clears the Watchdog timer Early Warning period elapsed flag, so that a new
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* early warning period can be detected.
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*/
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static inline void wdt_clear_early_warning(void)
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{
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Wdt *const WDT_module = WDT;
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WDT_module->INTFLAG.reg = WDT_INTFLAG_EW;
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}
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/**
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* Determines if the Watchdog timer Early Warning period has elapsed.
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*
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* \note If no early warning period was configured, the value returned by this
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* function is invalid.
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*
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* \return Current Watchdog Early Warning state.
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*/
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static inline bool wdt_is_early_warning(void)
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{
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Wdt *const WDT_module = WDT;
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return (WDT_module->INTFLAG.reg & WDT_INTFLAG_EW);
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}
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void wdt_reset_count(void);
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#endif /* WDT_H_INCLUDED */
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