1 /**
2   ******************************************************************************
3   * @file    stm32l5xx_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) 2019 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          STM32L5xx devices provide the capability to measure the LSI clock
55          frequency (LSI clock is internally connected to TIM16 CH1 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, IWDG_RLR and IWDG_WINR.
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       (++) Depending on window parameter:
80         (+++) If Window Init parameter is same as Window register value,
81              nothing more is done but reload counter value in order to exit
82              function with exact time base.
83         (+++) Else modify Window register. This will automatically reload
84              watchdog counter.
85       (++) Wait for status flags to be reset.
86 
87     (#) Then the application program must refresh the IWDG counter at regular
88         intervals during normal operation to prevent an MCU reset, using
89         HAL_IWDG_Refresh() function.
90 
91      *** IWDG HAL driver macros list ***
92      ====================================
93      [..]
94        Below the list of most used macros in IWDG HAL driver:
95       (+) __HAL_IWDG_START: Enable the IWDG peripheral
96       (+) __HAL_IWDG_RELOAD_COUNTER: Reloads IWDG counter with value defined in
97           the reload register
98 
99   @endverbatim
100   ******************************************************************************
101   */
102 
103 /* Includes ------------------------------------------------------------------*/
104 #include "stm32l5xx_hal.h"
105 
106 /** @addtogroup STM32L5xx_HAL_Driver
107   * @{
108   */
109 
110 #ifdef HAL_IWDG_MODULE_ENABLED
111 /** @addtogroup IWDG
112   * @brief IWDG HAL module driver.
113   * @{
114   */
115 
116 /* Private typedef -----------------------------------------------------------*/
117 /* Private define ------------------------------------------------------------*/
118 /** @defgroup IWDG_Private_Defines IWDG Private Defines
119   * @{
120   */
121 /* Status register needs up to 5 LSI clock periods divided by the clock
122    prescaler to be updated. The number of LSI clock periods is upper-rounded to
123    6 for the timeout value calculation.
124    The timeout value is also calculated using the highest prescaler (256) and
125    the LSI_VALUE constant. The value of this constant can be changed by the user
126    to take into account possible LSI clock period variations.
127    The timeout value is multiplied by 1000 to be converted in milliseconds. */
128 #define HAL_IWDG_DEFAULT_TIMEOUT        ((6UL * 256UL * 1000UL) / LSI_VALUE)
129 #define IWDG_KERNEL_UPDATE_FLAGS        (IWDG_SR_WVU | IWDG_SR_RVU | IWDG_SR_PVU)
130 /**
131   * @}
132   */
133 
134 /* Private macro -------------------------------------------------------------*/
135 /* Private variables ---------------------------------------------------------*/
136 /* Private function prototypes -----------------------------------------------*/
137 /* Exported functions --------------------------------------------------------*/
138 
139 /** @addtogroup IWDG_Exported_Functions
140   * @{
141   */
142 
143 /** @addtogroup IWDG_Exported_Functions_Group1
144   *  @brief    Initialization and Start functions.
145   *
146 @verbatim
147  ===============================================================================
148           ##### Initialization and Start functions #####
149  ===============================================================================
150  [..]  This section provides functions allowing to:
151       (+) Initialize the IWDG according to the specified parameters in the
152           IWDG_InitTypeDef of associated handle.
153       (+) Manage Window option.
154       (+) Once initialization is performed in HAL_IWDG_Init function, Watchdog
155           is reloaded in order to exit function with correct time base.
156 
157 @endverbatim
158   * @{
159   */
160 
161 /**
162   * @brief  Initialize the IWDG according to the specified parameters in the
163   *         IWDG_InitTypeDef and start watchdog. Before exiting function,
164   *         watchdog is refreshed in order to have correct time base.
165   * @param  hiwdg  pointer to a IWDG_HandleTypeDef structure that contains
166   *                the configuration information for the specified IWDG module.
167   * @retval HAL status
168   */
HAL_IWDG_Init(IWDG_HandleTypeDef * hiwdg)169 HAL_StatusTypeDef HAL_IWDG_Init(IWDG_HandleTypeDef *hiwdg)
170 {
171   uint32_t tickstart;
172 
173   /* Check the IWDG handle allocation */
174   if (hiwdg == NULL)
175   {
176     return HAL_ERROR;
177   }
178 
179   /* Check the parameters */
180   assert_param(IS_IWDG_ALL_INSTANCE(hiwdg->Instance));
181   assert_param(IS_IWDG_PRESCALER(hiwdg->Init.Prescaler));
182   assert_param(IS_IWDG_RELOAD(hiwdg->Init.Reload));
183   assert_param(IS_IWDG_WINDOW(hiwdg->Init.Window));
184 
185   /* Enable IWDG. LSI is turned on automatically */
186   __HAL_IWDG_START(hiwdg);
187 
188   /* Enable write access to IWDG_PR, IWDG_RLR and IWDG_WINR registers by writing
189   0x5555 in KR */
190   IWDG_ENABLE_WRITE_ACCESS(hiwdg);
191 
192   /* Write to IWDG registers the Prescaler & Reload values to work with */
193   hiwdg->Instance->PR = hiwdg->Init.Prescaler;
194   hiwdg->Instance->RLR = hiwdg->Init.Reload;
195 
196   /* Check pending flag, if previous update not done, return timeout */
197   tickstart = HAL_GetTick();
198 
199   /* Wait for register to be updated */
200   while ((hiwdg->Instance->SR & IWDG_KERNEL_UPDATE_FLAGS) != 0x00u)
201   {
202     if ((HAL_GetTick() - tickstart) > HAL_IWDG_DEFAULT_TIMEOUT)
203     {
204       if ((hiwdg->Instance->SR & IWDG_KERNEL_UPDATE_FLAGS) != 0x00u)
205       {
206         return HAL_TIMEOUT;
207       }
208     }
209   }
210 
211   /* If window parameter is different than current value, modify window
212   register */
213   if (hiwdg->Instance->WINR != hiwdg->Init.Window)
214   {
215     /* Write to IWDG WINR the IWDG_Window value to compare with. In any case,
216     even if window feature is disabled, Watchdog will be reloaded by writing
217     windows register */
218     hiwdg->Instance->WINR = hiwdg->Init.Window;
219   }
220   else
221   {
222     /* Reload IWDG counter with value defined in the reload register */
223     __HAL_IWDG_RELOAD_COUNTER(hiwdg);
224   }
225 
226   /* Return function status */
227   return HAL_OK;
228 }
229 
230 
231 /**
232   * @}
233   */
234 
235 
236 /** @addtogroup IWDG_Exported_Functions_Group2
237   *  @brief   IO operation functions
238   *
239 @verbatim
240  ===============================================================================
241                       ##### IO operation functions #####
242  ===============================================================================
243  [..]  This section provides functions allowing to:
244       (+) Refresh the IWDG.
245 
246 @endverbatim
247   * @{
248   */
249 
250 /**
251   * @brief  Refresh the IWDG.
252   * @param  hiwdg  pointer to a IWDG_HandleTypeDef structure that contains
253   *                the configuration information for the specified IWDG module.
254   * @retval HAL status
255   */
HAL_IWDG_Refresh(IWDG_HandleTypeDef * hiwdg)256 HAL_StatusTypeDef HAL_IWDG_Refresh(IWDG_HandleTypeDef *hiwdg)
257 {
258   /* Reload IWDG counter with value defined in the reload register */
259   __HAL_IWDG_RELOAD_COUNTER(hiwdg);
260 
261   /* Return function status */
262   return HAL_OK;
263 }
264 
265 
266 /**
267   * @}
268   */
269 
270 /**
271   * @}
272   */
273 
274 #endif /* HAL_IWDG_MODULE_ENABLED */
275 /**
276   * @}
277   */
278 
279 /**
280   * @}
281   */
282 
283