S32K312软件看门狗之Software Watchdog Timer (SWT)

S32DS的SDK中提供了Wdg，是属于MCAL层的，配置有点复杂，还需要以来Gpt、Mcu和Platform框架里的东西，配置到已经开发好的工程中还容易出现配置问题。本文主要讲解Software Watchdog Timer (SWT)的软件看门狗配置和使用示例，这个看门狗属于Drivers层的，配置和使用很简单，也无需额外以来其他组件。

示例Demo工程，极限喂狗时间设置为2秒，操作模式设置为喂狗超时就重启。另一种操作模式是中断通知，需要依赖中断组件，不是本次描述重点。

Software Watchdog Timer (SWT)组件添加如下图所示：

为了方便查看，在代码中引入RTT日志打印的代码。

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测试代码如下：

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/*==================================================================================================
*   Project              : RTD AUTOSAR 4.4
*   Platform             : CORTEXM
*   Peripheral           : S32K3XX
*   Dependencies         : none
*
*   Autosar Version      : 4.4.0
*   Autosar Revision     : ASR_REL_4_4_REV_0000
*   Autosar Conf.Variant :
*   SW Version           : 2.0.1
*   Build Version        : S32K3_RTD_2_0_1_D2207_ASR_REL_4_4_REV_0000_20220707
*
*   (c) Copyright 2020 - 2021 NXP Semiconductors
*   All Rights Reserved.
*
*   NXP Confidential. This software is owned or controlled by NXP and may only be
*   used strictly in accordance with the applicable license terms. By expressly
*   accepting such terms or by downloading, installing, activating and/or otherwise
*   using the software, you are agreeing that you have read, and that you agree to
*   comply with and are bound by, such license terms. If you do not agree to be
*   bound by the applicable license terms, then you may not retain, install,
*   activate or otherwise use the software.
==================================================================================================*/

/**
*   @file main.c
*
*   @addtogroup main_module main module documentation
*   @{
*/

/* Including necessary configuration files. */
#include "Clock_Ip.h"

#include "Swt_Ip_BOARD_InitPeripherals_PBcfg.h"
#include "Swt_Ip.h"

volatile int exit_code = 0;
/* User includes */
#include "SEGGER_RTT_Conf.h"
#include "SEGGER_RTT.h"

#define SWT_INST                     0U

void delay(uint32 timeout)
{
    volatile uint32 i = timeout;

    while(i--);
}

/*!
  \brief The main function for the project.
  \details The startup initialization sequence is the following:
 * - startup asm routine
 * - main()
*/
int main(void)
{
    /* Write your code here */
	SEGGER_RTT_printf(0,"Clock_Ip_InitClock ... \n");
	Clock_Ip_InitClock(&Clock_Ip_aClockConfig[0]);

	/*Initialize SWT */
	SEGGER_RTT_printf(0,"Swt_Ip_Init ... \n");
	Swt_Ip_Init(SWT_INST, &Swt_Ip_Cfg0);

	for(;;)
	{
		SEGGER_RTT_printf(0,"Swt_Ip_Service ... \n");
		Swt_Ip_Service(SWT_INST);
		delay(1*16000000U);
	}

    for(;;)
    {
        if(exit_code != 0)
        {
            break;
        }
    }
    return exit_code;
}

/** @} */

?极限喂狗时间设置为2秒，我们一秒左右喂狗一次的效果如图

我们3秒左右喂狗一次的效果如下：

因为3秒喂狗，已经超过了极限喂狗时间，所以程序反复重启。

综上所述，已经到了我们使用和验证软件看门狗的目的了。