1 /**
2 ******************************************************************************
3 * @file stm32f4xx_iwdg.c
4 * @author MCD Application Team
5 * @version V1.4.0
6 * @date 04-August-2014
7 * @brief This file provides firmware functions to manage the following
8 * functionalities of the Independent watchdog (IWDG) peripheral:
9 * + Prescaler and Counter configuration
10 * + IWDG activation
11 * + Flag management
12 *
13 @verbatim
14 ===============================================================================
15 ##### IWDG features #####
16 ===============================================================================
17 [..]
18 The IWDG can be started by either software or hardware (configurable
19 through option byte).
20
21 The IWDG is clocked by its own dedicated low-speed clock (LSI) and
22 thus stays active even if the main clock fails.
23 Once the IWDG is started, the LSI is forced ON and cannot be disabled
24 (LSI cannot be disabled too), and the counter starts counting down from
25 the reset value of 0xFFF. When it reaches the end of count value (0x000)
26 a system reset is generated.
27 The IWDG counter should be reloaded at regular intervals to prevent
28 an MCU reset.
29
30 The IWDG is implemented in the VDD voltage domain that is still functional
31 in STOP and STANDBY mode (IWDG reset can wake-up from STANDBY).
32
33 IWDGRST flag in RCC_CSR register can be used to inform when a IWDG
34 reset occurs.
35
36 Min-max timeout value @32KHz (LSI): ~125us / ~32.7s
37 The IWDG timeout may vary due to LSI frequency dispersion. STM32F4xx
38 devices provide the capability to measure the LSI frequency (LSI clock
39 connected internally to TIM5 CH4 input capture). The measured value
40 can be used to have an IWDG timeout with an acceptable accuracy.
41 For more information, please refer to the STM32F4xx Reference manual
42
43 ##### How to use this driver #####
44 ===============================================================================
45 [..]
46 (#) Enable write access to IWDG_PR and IWDG_RLR registers using
47 IWDG_WriteAccessCmd(IWDG_WriteAccess_Enable) function
48
49 (#) Configure the IWDG prescaler using IWDG_SetPrescaler() function
50
51 (#) Configure the IWDG counter value using IWDG_SetReload() function.
52 This value will be loaded in the IWDG counter each time the counter
53 is reloaded, then the IWDG will start counting down from this value.
54
55 (#) Start the IWDG using IWDG_Enable() function, when the IWDG is used
56 in software mode (no need to enable the LSI, it will be enabled
57 by hardware)
58
59 (#) Then the application program must reload the IWDG counter at regular
60 intervals during normal operation to prevent an MCU reset, using
61 IWDG_ReloadCounter() function.
62
63 @endverbatim
64 ******************************************************************************
65 * @attention
66 *
67 * <h2><center>© COPYRIGHT 2014 STMicroelectronics</center></h2>
68 *
69 * Licensed under MCD-ST Liberty SW License Agreement V2, (the "License");
70 * You may not use this file except in compliance with the License.
71 * You may obtain a copy of the License at:
72 *
73 * http://www.st.com/software_license_agreement_liberty_v2
74 *
75 * Unless required by applicable law or agreed to in writing, software
76 * distributed under the License is distributed on an "AS IS" BASIS,
77 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
78 * See the License for the specific language governing permissions and
79 * limitations under the License.
80 *
81 ******************************************************************************
82 */
83
84 /* Includes ------------------------------------------------------------------*/
85 #include "stm32f4xx_iwdg.h"
86
87 /** @addtogroup STM32F4xx_StdPeriph_Driver
88 * @{
89 */
90
91 /** @defgroup IWDG
92 * @brief IWDG driver modules
93 * @{
94 */
95
96 /* Private typedef -----------------------------------------------------------*/
97 /* Private define ------------------------------------------------------------*/
98
99 /* KR register bit mask */
100 #define KR_KEY_RELOAD ((uint16_t)0xAAAA)
101 #define KR_KEY_ENABLE ((uint16_t)0xCCCC)
102
103 /* Private macro -------------------------------------------------------------*/
104 /* Private variables ---------------------------------------------------------*/
105 /* Private function prototypes -----------------------------------------------*/
106 /* Private functions ---------------------------------------------------------*/
107
108 /** @defgroup IWDG_Private_Functions
109 * @{
110 */
111
112 /** @defgroup IWDG_Group1 Prescaler and Counter configuration functions
113 * @brief Prescaler and Counter configuration functions
114 *
115 @verbatim
116 ===============================================================================
117 ##### Prescaler and Counter configuration functions #####
118 ===============================================================================
119
120 @endverbatim
121 * @{
122 */
123
124 /**
125 * @brief Enables or disables write access to IWDG_PR and IWDG_RLR registers.
126 * @param IWDG_WriteAccess: new state of write access to IWDG_PR and IWDG_RLR registers.
127 * This parameter can be one of the following values:
128 * @arg IWDG_WriteAccess_Enable: Enable write access to IWDG_PR and IWDG_RLR registers
129 * @arg IWDG_WriteAccess_Disable: Disable write access to IWDG_PR and IWDG_RLR registers
130 * @retval None
131 */
IWDG_WriteAccessCmd(uint16_t IWDG_WriteAccess)132 void IWDG_WriteAccessCmd(uint16_t IWDG_WriteAccess)
133 {
134 /* Check the parameters */
135 assert_param(IS_IWDG_WRITE_ACCESS(IWDG_WriteAccess));
136 IWDG->KR = IWDG_WriteAccess;
137 }
138
139 /**
140 * @brief Sets IWDG Prescaler value.
141 * @param IWDG_Prescaler: specifies the IWDG Prescaler value.
142 * This parameter can be one of the following values:
143 * @arg IWDG_Prescaler_4: IWDG prescaler set to 4
144 * @arg IWDG_Prescaler_8: IWDG prescaler set to 8
145 * @arg IWDG_Prescaler_16: IWDG prescaler set to 16
146 * @arg IWDG_Prescaler_32: IWDG prescaler set to 32
147 * @arg IWDG_Prescaler_64: IWDG prescaler set to 64
148 * @arg IWDG_Prescaler_128: IWDG prescaler set to 128
149 * @arg IWDG_Prescaler_256: IWDG prescaler set to 256
150 * @retval None
151 */
IWDG_SetPrescaler(uint8_t IWDG_Prescaler)152 void IWDG_SetPrescaler(uint8_t IWDG_Prescaler)
153 {
154 /* Check the parameters */
155 assert_param(IS_IWDG_PRESCALER(IWDG_Prescaler));
156 IWDG->PR = IWDG_Prescaler;
157 }
158
159 /**
160 * @brief Sets IWDG Reload value.
161 * @param Reload: specifies the IWDG Reload value.
162 * This parameter must be a number between 0 and 0x0FFF.
163 * @retval None
164 */
IWDG_SetReload(uint16_t Reload)165 void IWDG_SetReload(uint16_t Reload)
166 {
167 /* Check the parameters */
168 assert_param(IS_IWDG_RELOAD(Reload));
169 IWDG->RLR = Reload;
170 }
171
172 /**
173 * @brief Reloads IWDG counter with value defined in the reload register
174 * (write access to IWDG_PR and IWDG_RLR registers disabled).
175 * @param None
176 * @retval None
177 */
IWDG_ReloadCounter(void)178 void IWDG_ReloadCounter(void)
179 {
180 IWDG->KR = KR_KEY_RELOAD;
181 }
182
183 /**
184 * @}
185 */
186
187 /** @defgroup IWDG_Group2 IWDG activation function
188 * @brief IWDG activation function
189 *
190 @verbatim
191 ===============================================================================
192 ##### IWDG activation function #####
193 ===============================================================================
194
195 @endverbatim
196 * @{
197 */
198
199 /**
200 * @brief Enables IWDG (write access to IWDG_PR and IWDG_RLR registers disabled).
201 * @param None
202 * @retval None
203 */
IWDG_Enable(void)204 void IWDG_Enable(void)
205 {
206 IWDG->KR = KR_KEY_ENABLE;
207 }
208
209 /**
210 * @}
211 */
212
213 /** @defgroup IWDG_Group3 Flag management function
214 * @brief Flag management function
215 *
216 @verbatim
217 ===============================================================================
218 ##### Flag management function #####
219 ===============================================================================
220
221 @endverbatim
222 * @{
223 */
224
225 /**
226 * @brief Checks whether the specified IWDG flag is set or not.
227 * @param IWDG_FLAG: specifies the flag to check.
228 * This parameter can be one of the following values:
229 * @arg IWDG_FLAG_PVU: Prescaler Value Update on going
230 * @arg IWDG_FLAG_RVU: Reload Value Update on going
231 * @retval The new state of IWDG_FLAG (SET or RESET).
232 */
IWDG_GetFlagStatus(uint16_t IWDG_FLAG)233 FlagStatus IWDG_GetFlagStatus(uint16_t IWDG_FLAG)
234 {
235 FlagStatus bitstatus = RESET;
236 /* Check the parameters */
237 assert_param(IS_IWDG_FLAG(IWDG_FLAG));
238 if ((IWDG->SR & IWDG_FLAG) != (uint32_t)RESET)
239 {
240 bitstatus = SET;
241 }
242 else
243 {
244 bitstatus = RESET;
245 }
246 /* Return the flag status */
247 return bitstatus;
248 }
249
250 /**
251 * @}
252 */
253
254 /**
255 * @}
256 */
257
258 /**
259 * @}
260 */
261
262 /**
263 * @}
264 */
265
266 /************************ (C) COPYRIGHT STMicroelectronics *****END OF FILE****/
267