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Rev	Author	Line No.	Line
2	mjames	1	/**
		2	******************************************************************************
		3	* @file stm32f1xx_hal_iwdg.c
		4	* @author MCD Application Team
		5	* @brief IWDG HAL module driver.
		6	* This file provides firmware functions to manage the following
		7	* functionalities of the Independent Watchdog (IWDG) peripheral:
		8	* + Initialization and Start functions
		9	* + IO operation functions
		10	*
		11	******************************************************************************
		12	* @attention
		13	*
		14	* Copyright (c) 2016 STMicroelectronics.
		15	* All rights reserved.
		16	*
		17	* This software is licensed under terms that can be found in the LICENSE file
		18	* in the root directory of this software component.
		19	* If no LICENSE file comes with this software, it is provided AS-IS.
		20	*
		21	******************************************************************************
		22	@verbatim
		23	==============================================================================
		24	##### IWDG Generic features #####
		25	==============================================================================
		26	[..]
		27	(+) The IWDG can be started by either software or hardware (configurable
		28	through option byte).
		29
		30	(+) The IWDG is clocked by the Low-Speed Internal clock (LSI) and thus stays
		31	active even if the main clock fails.
		32
		33	(+) Once the IWDG is started, the LSI is forced ON and both cannot be
		34	disabled. The counter starts counting down from the reset value (0xFFF).
		35	When it reaches the end of count value (0x000) a reset signal is
		36	generated (IWDG reset).
		37
		38	(+) Whenever the key value 0x0000 AAAA is written in the IWDG_KR register,
		39	the IWDG_RLR value is reloaded into the counter and the watchdog reset
		40	is prevented.
		41
		42	(+) The IWDG is implemented in the VDD voltage domain that is still functional
		43	in STOP and STANDBY mode (IWDG reset can wake up the CPU from STANDBY).
		44	IWDGRST flag in RCC_CSR register can be used to inform when an IWDG
		45	reset occurs.
		46
		47	(+) Debug mode: When the microcontroller enters debug mode (core halted),
		48	the IWDG counter either continues to work normally or stops, depending
		49	on DBG_IWDG_STOP configuration bit in DBG module, accessible through
		50	__HAL_DBGMCU_FREEZE_IWDG() and __HAL_DBGMCU_UNFREEZE_IWDG() macros.
		51
		52	[..] Min-max timeout value @32KHz (LSI): ~125us / ~32.7s
		53	The IWDG timeout may vary due to LSI clock frequency dispersion.
		54	STM32F1xx devices provide the capability to measure the LSI clock
		55	frequency (LSI clock is internally connected to TIM5 CH4 input capture).
		56	The measured value can be used to have an IWDG timeout with an
		57	acceptable accuracy.
		58
		59	[..] Default timeout value (necessary for IWDG_SR status register update):
		60	Constant LSI_VALUE is defined based on the nominal LSI clock frequency.
		61	This frequency being subject to variations as mentioned above, the
		62	default timeout value (defined through constant HAL_IWDG_DEFAULT_TIMEOUT
		63	below) may become too short or too long.
		64	In such cases, this default timeout value can be tuned by redefining
		65	the constant LSI_VALUE at user-application level (based, for instance,
		66	on the measured LSI clock frequency as explained above).
		67
		68	##### How to use this driver #####
		69	==============================================================================
		70	[..]
		71	(#) Use IWDG using HAL_IWDG_Init() function to :
		72	(++) Enable instance by writing Start keyword in IWDG_KEY register. LSI
		73	clock is forced ON and IWDG counter starts counting down.
		74	(++) Enable write access to configuration registers:
		75	IWDG_PR and IWDG_RLR.
		76	(++) Configure the IWDG prescaler and counter reload value. This reload
		77	value will be loaded in the IWDG counter each time the watchdog is
		78	reloaded, then the IWDG will start counting down from this value.
		79	(++) Wait for status flags to be reset.
		80
		81	(#) Then the application program must refresh the IWDG counter at regular
		82	intervals during normal operation to prevent an MCU reset, using
		83	HAL_IWDG_Refresh() function.
		84
		85	* IWDG HAL driver macros list *
		86	====================================
		87	[..]
		88	Below the list of most used macros in IWDG HAL driver:
		89	(+) __HAL_IWDG_START: Enable the IWDG peripheral
		90	(+) __HAL_IWDG_RELOAD_COUNTER: Reloads IWDG counter with value defined in
		91	the reload register
		92
		93	@endverbatim
		94	*/
		95
		96	/* Includes ------------------------------------------------------------------*/
		97	#include "stm32f1xx_hal.h"
		98
		99	/** @addtogroup STM32F1xx_HAL_Driver
		100	* @{
		101	*/
		102
		103	#ifdef HAL_IWDG_MODULE_ENABLED
		104	/** @addtogroup IWDG
		105	* @brief IWDG HAL module driver.
		106	* @{
		107	*/
		108
		109	/* Private typedef -----------------------------------------------------------*/
		110	/* Private define ------------------------------------------------------------*/
		111	/** @defgroup IWDG_Private_Defines IWDG Private Defines
		112	* @{
		113	*/
		114	/* Status register needs up to 5 LSI clock periods divided by the clock
		115	prescaler to be updated. The number of LSI clock periods is upper-rounded to
		116	6 for the timeout value calculation.
		117	The timeout value is calculated using the highest prescaler (256) and
		118	the LSI_VALUE constant. The value of this constant can be changed by the user
		119	to take into account possible LSI clock period variations.
		120	The timeout value is multiplied by 1000 to be converted in milliseconds.
		121	LSI startup time is also considered here by adding LSI_STARTUP_TIME
		122	converted in milliseconds. */
		123	#define HAL_IWDG_DEFAULT_TIMEOUT (((6UL * 256UL * 1000UL) / LSI_VALUE) + ((LSI_STARTUP_TIME / 1000UL) + 1UL))
		124	#define IWDG_KERNEL_UPDATE_FLAGS (IWDG_SR_RVU \| IWDG_SR_PVU)
		125	/**
		126	* @}
		127	*/
		128
		129	/* Private macro -------------------------------------------------------------*/
		130	/* Private variables ---------------------------------------------------------*/
		131	/* Private function prototypes -----------------------------------------------*/
		132	/* Exported functions --------------------------------------------------------*/
		133
		134	/** @addtogroup IWDG_Exported_Functions
		135	* @{
		136	*/
		137
		138	/** @addtogroup IWDG_Exported_Functions_Group1
		139	* @brief Initialization and Start functions.
		140	*
		141	@verbatim
		142	===============================================================================
		143	##### Initialization and Start functions #####
		144	===============================================================================
		145	[..] This section provides functions allowing to:
		146	(+) Initialize the IWDG according to the specified parameters in the
		147	IWDG_InitTypeDef of associated handle.
		148	(+) Once initialization is performed in HAL_IWDG_Init function, Watchdog
		149	is reloaded in order to exit function with correct time base.
		150
		151	@endverbatim
		152	* @{
		153	*/
		154
		155	/**
		156	* @brief Initialize the IWDG according to the specified parameters in the
		157	* IWDG_InitTypeDef and start watchdog. Before exiting function,
		158	* watchdog is refreshed in order to have correct time base.
		159	* @param hiwdg pointer to a IWDG_HandleTypeDef structure that contains
		160	* the configuration information for the specified IWDG module.
		161	* @retval HAL status
		162	*/
		163	HAL_StatusTypeDef HAL_IWDG_Init(IWDG_HandleTypeDef *hiwdg)
		164	{
		165	uint32_t tickstart;
		166
		167	/* Check the IWDG handle allocation */
		168	if (hiwdg == NULL)
		169	{
		170	return HAL_ERROR;
		171	}
		172
		173	/* Check the parameters */
		174	assert_param(IS_IWDG_ALL_INSTANCE(hiwdg->Instance));
		175	assert_param(IS_IWDG_PRESCALER(hiwdg->Init.Prescaler));
		176	assert_param(IS_IWDG_RELOAD(hiwdg->Init.Reload));
		177
		178	/* Enable IWDG. LSI is turned on automatically */
		179	__HAL_IWDG_START(hiwdg);
		180
		181	/* Enable write access to IWDG_PR and IWDG_RLR registers by writing
		182	0x5555 in KR */
		183	IWDG_ENABLE_WRITE_ACCESS(hiwdg);
		184
		185	/* Write to IWDG registers the Prescaler & Reload values to work with */
		186	hiwdg->Instance->PR = hiwdg->Init.Prescaler;
		187	hiwdg->Instance->RLR = hiwdg->Init.Reload;
		188
		189	/* Check pending flag, if previous update not done, return timeout */
		190	tickstart = HAL_GetTick();
		191
		192	/* Wait for register to be updated */
		193	while ((hiwdg->Instance->SR & IWDG_KERNEL_UPDATE_FLAGS) != 0x00u)
		194	{
		195	if ((HAL_GetTick() - tickstart) > HAL_IWDG_DEFAULT_TIMEOUT)
		196	{
		197	if ((hiwdg->Instance->SR & IWDG_KERNEL_UPDATE_FLAGS) != 0x00u)
		198	{
		199	return HAL_TIMEOUT;
		200	}
		201	}
		202	}
		203
		204	/* Reload IWDG counter with value defined in the reload register */
		205	__HAL_IWDG_RELOAD_COUNTER(hiwdg);
		206
		207	/* Return function status */
		208	return HAL_OK;
		209	}
		210
		211
		212	/**
		213	* @}
		214	*/
		215
		216
		217	/** @addtogroup IWDG_Exported_Functions_Group2
		218	* @brief IO operation functions
		219	*
		220	@verbatim
		221	===============================================================================
		222	##### IO operation functions #####
		223	===============================================================================
		224	[..] This section provides functions allowing to:
		225	(+) Refresh the IWDG.
		226
		227	@endverbatim
		228	* @{
		229	*/
		230
		231	/**
		232	* @brief Refresh the IWDG.
		233	* @param hiwdg pointer to a IWDG_HandleTypeDef structure that contains
		234	* the configuration information for the specified IWDG module.
		235	* @retval HAL status
		236	*/
		237	HAL_StatusTypeDef HAL_IWDG_Refresh(IWDG_HandleTypeDef *hiwdg)
		238	{
		239	/* Reload IWDG counter with value defined in the reload register */
		240	__HAL_IWDG_RELOAD_COUNTER(hiwdg);
		241
		242	/* Return function status */
		243	return HAL_OK;
		244	}
		245
		246
		247	/**
		248	* @}
		249	*/
		250
		251	/**
		252	* @}
		253	*/
		254
		255	#endif /* HAL_IWDG_MODULE_ENABLED */
		256	/**
		257	* @}
		258	*/
		259
		260	/**
		261	* @}
		262	*/

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