stm32F4系列MCU，窗口看门狗 WWDG中的bug
stm32F4系列MCU，窗口看门狗 WWDG中的bug。
1. 如果使能预喂狗中断，那么必须满足如下两点
（1）在开启wwdg中断之前，需要先将 SR 寄存器中的EWI标志位清零，否则会看门狗会不断复位
（2）在wwdg_irq里加上一小段延时，否则看门狗会不断复位
2. 如果系统里还有其他中断，比如按键，在按键中断中设置一个变量，这个变量在wwdg_isr中读取，来决定是否停止喂狗
这样按下按键以后，系统直接就飞了。
这里给出一个测试代码。 如下所示。
1. 如果使能预喂狗中断，那么必须满足如下两点
（1）在开启wwdg中断之前，需要先将 SR 寄存器中的EWI标志位清零，否则会看门狗会不断复位
（2）在wwdg_irq里加上一小段延时，否则看门狗会不断复位
2. 如果系统里还有其他中断，比如按键，在按键中断中设置一个变量，这个变量在wwdg_isr中读取，来决定是否停止喂狗
这样按下按键以后，系统直接就飞了。
这里给出一个测试代码。 如下所示。
/**
******************************************************************************
* @file USART/USART_Printf/main.c
* @author MCD Application Team
* @version V1.0.1
* @date 13-April-2012
* @brief Main program body
******************************************************************************
* @attention
*
* <h2><center>© COPYRIGHT 2012 STMicroelectronics</center></h2>
*
* Licensed under MCD-ST Liberty SW License Agreement V2, (the "License");
* You may not use this file except in compliance with the License.
* You may obtain a copy of the License at:
*
* http://www.st.com/software_license_agreement_liberty_v2
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*
******************************************************************************
*/
/* Includes ------------------------------------------------------------------*/
#include "stm32f4xx.h"
#include "stm324xg_eval.h"
#include <stdio.h>
/** @addtogroup STM32F4xx_StdPeriph_Examples
* @{
*/
/** @addtogroup USART_Printf
* @{
*/
/* Private typedef -----------------------------------------------------------*/
/* Private define ------------------------------------------------------------*/
/* Private macro -------------------------------------------------------------*/
/* Private variables ---------------------------------------------------------*/
USART_InitTypeDef USART_InitStructure;
/* Private function prototypes -----------------------------------------------*/
#ifdef __GNUC__
/* With GCC/RAISONANCE, small printf (option LD Linker->Libraries->Small printf
set to 'Yes') calls __io_putchar() */
#define PUTCHAR_PROTOTYPE int __io_putchar(int ch)
#else
#define PUTCHAR_PROTOTYPE int fputc(int ch, FILE *f)
#endif /* __GNUC__ */
/* Private functions ---------------------------------------------------------*/
void delay(int t);
void wwdg_nvic_config(void);
void key_init(void);
/**
* @brief Main program
* @param None
* @retval None
*/
int main(void)
{
int i = 0;
RCC_AHB1PeriphClockCmd(RCC_AHB1Periph_GPIOB, ENABLE);
/*!< At this stage the microcontroller clock setting is already configured,
this is done through SystemInit() function which is called from startup
file (startup_stm32f4xx.s) before to branch to application main.
To reconfigure the default setting of SystemInit() function, refer to
system_stm32f4xx.c file
*/
/* USARTx configured as follow:
- BaudRate = 115200 baud
- Word Length = 8 Bits
- One Stop Bit
- No parity
- Hardware flow control disabled (RTS and CTS signals)
- Receive and transmit enabled
*/
USART_InitStructure.USART_BaudRate = 115200;
USART_InitStructure.USART_WordLength = USART_WordLength_8b;
USART_InitStructure.USART_StopBits = USART_StopBits_1;
USART_InitStructure.USART_Parity = USART_Parity_No;
USART_InitStructure.USART_HardwareFlowControl = USART_HardwareFlowControl_None;
USART_InitStructure.USART_Mode = USART_Mode_Rx | USART_Mode_Tx;
STM_EVAL_COMInit(COM1, &USART_InitStructure);
/* Output a message on Hyperterminal using printf function */
printf("\n\rUSART Printf Example\n\r");
/* key configuration */
key_init();
/* WWDG configuration */
/* Enable WWDG clock */
RCC_APB1PeriphClockCmd(RCC_APB1Periph_WWDG, ENABLE);
/* WWDG clock counter = (PCLK1 (42MHz)/4096)/8 = 1281 Hz (~780 us) */
WWDG_SetPrescaler(WWDG_Prescaler_8);
/* Set Window value to 80; WWDG counter should be refreshed only when the counter
is below 80 (and greater than 64) otherwise a reset will be generated */
WWDG_SetWindowValue(120);
/* Enable WWDG and set counter value to 127, WWDG timeout = ~780 us * 64 = 49.92 ms
In this case the refresh window is: ~780 * (127-80) = 36.6ms < refresh window < ~780 * 64 = 49.9ms
*/
WWDG_Enable(127);
wwdg_nvic_config();
WWDG->SR = 0;
WWDG_EnableIT();
while (1)
{
printf("%d\r\n", i++);
delay(1000);
}
}
void delay(int t)
{
int i,j;
for(i=0; i<t; i++)
for(j=0; j<10000;j++)
;
}
/**
* @brief Retargets the C library printf function to the USART.
* @param None
* @retval None
*/
PUTCHAR_PROTOTYPE
{
/* Place your implementation of fputc here */
/* e.g. write a character to the USART */
USART_SendData(EVAL_COM1, (uint8_t) ch);
/* Loop until the end of transmission */
while (USART_GetFlagStatus(EVAL_COM1, USART_FLAG_TC) == RESET)
{}
return ch;
}
#ifdef USE_FULL_ASSERT
/**
* @brief Reports the name of the source file and the source line number
* where the assert_param error has occurred.
* @param file: pointer to the source file name
* @param line: assert_param error line source number
* @retval None
*/
void assert_failed(uint8_t* file, uint32_t line)
{
/* User can add his own implementation to report the file name and line number,
ex: printf("Wrong parameters value: file %s on line %d\r\n", file, line) */
/* Infinite loop */
while (1)
{
}
}
#endif
/**
* @}
*/
static int wwdg_clear_flag = 0;
void WWDG_IRQHandler(void)
{
WWDG->SR = 0;
if (wwdg_clear_flag == 0) //wwdg_clear_flag 在按键中断中被设置为1
{
/* Update WWDG counter */
WWDG->CR = 127 & 0x7F;
delay(1);
}
}
void wwdg_nvic_config(void)
{
NVIC_InitTypeDef NVIC_InitStructure;
NVIC_InitStructure.NVIC_IRQChannel = WWDG_IRQn;
NVIC_InitStructure.NVIC_IRQChannelPreemptionPriority = 0;
NVIC_InitStructure.NVIC_IRQChannelSubPriority = 1;
NVIC_InitStructure.NVIC_IRQChannelCmd = ENABLE;
NVIC_Init(&NVIC_InitStructure);
}
static void key_gpio_init(void)
{
GPIO_InitTypeDef GPIO_InitStructure;
/* 使能时钟 */
RCC_AHB1PeriphClockCmd(RCC_AHB1Periph_GPIOA | \
RCC_AHB1Periph_GPIOF | \
RCC_AHB1Periph_GPIOD,
ENABLE);
GPIO_InitStructure.GPIO_Mode = GPIO_Mode_IN;
GPIO_InitStructure.GPIO_Speed = GPIO_Speed_2MHz;
GPIO_InitStructure.GPIO_OType = GPIO_OType_PP;
GPIO_InitStructure.GPIO_PuPd = GPIO_PuPd_DOWN;
/* 初始化中断按键 */
GPIO_InitStructure.GPIO_Pin = GPIO_Pin_0;
GPIO_Init(GPIOA, &GPIO_InitStructure);
/* 初始化轮询按键 */
GPIO_InitStructure.GPIO_Pin = GPIO_Pin_6 | GPIO_Pin_7 | GPIO_Pin_8
| GPIO_Pin_9 | GPIO_Pin_10 | GPIO_Pin_11;
GPIO_Init(GPIOF, &GPIO_InitStructure);
/* 初始化LED引脚 */
GPIO_InitStructure.GPIO_Pin = GPIO_Pin_3;
GPIO_InitStructure.GPIO_Mode = GPIO_Mode_OUT;
GPIO_Init(GPIOD, &GPIO_InitStructure);
}
static void key_exti_config(void)
{
EXTI_InitTypeDef EXTI_InitStructure;
/* 连接PA0到外部中断线0 */
SYSCFG_EXTILineConfig(EXTI_PortSourceGPIOA, EXTI_PinSource0);
/* 配置外部中断线0 */
EXTI_InitStructure.EXTI_Line = EXTI_Line0;
EXTI_InitStructure.EXTI_Mode = EXTI_Mode_Interrupt;
EXTI_InitStructure.EXTI_Trigger = EXTI_Trigger_Rising_Falling;
EXTI_InitStructure.EXTI_LineCmd = ENABLE;
EXTI_Init(&EXTI_InitStructure);
}
static void key_nvic_config(void)
{
NVIC_InitTypeDef NVIC_InitStructure;
/* 使能外部中断0 */
NVIC_InitStructure.NVIC_IRQChannel = EXTI0_IRQn;
NVIC_InitStructure.NVIC_IRQChannelPreemptionPriority = 0x3;
NVIC_InitStructure.NVIC_IRQChannelSubPriority = 0x3;
NVIC_InitStructure.NVIC_IRQChannelCmd = ENABLE;
NVIC_Init(&NVIC_InitStructure);
}
void key_init(void)
{
key_gpio_init();
key_exti_config();
key_nvic_config();
}
void EXTI0_IRQHandler(void)
{
extern int stop_feed_dog;
/* 清除中断标志 */
printf("key isr\r\n");
wwdg_clear_flag = 1;
EXTI_ClearITPendingBit(EXTI_Line0);
}
/**
* @}
*/
/************************ (C) COPYRIGHT STMicroelectronics *****END OF FILE****/