LibrePilot/flight/PiOS/STM32F10x/pios_wdg.c

/**
 ******************************************************************************
 * @addtogroup PIOS PIOS Core hardware abstraction layer
 * @{
 * @addtogroup   PIOS_WDG Watchdog Functions
 * @brief PIOS Comamnds to initialize and clear watchdog timer
 * @{
 *
 * @file       pios_spi.c
 * @author     The OpenPilot Team, http://www.openpilot.org Copyright (C) 2010.
 * 	        Parts by Thorsten Klose (tk@midibox.org) (tk@midibox.org)
 * @brief      Hardware Abstraction Layer for SPI ports of STM32
 * @see        The GNU Public License (GPL) Version 3
 * @notes
 *
 * The PIOS Watchdog provides a HAL to initialize a watchdog 
 *
 *****************************************************************************/
/*
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 3 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful, but
 * WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
 * or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
 * for more details.
 *
 * You should have received a copy of the GNU General Public License along
 * with this program; if not, write to the Free Software Foundation, Inc.,
 * 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
 */


#include "pios.h"
#include "stm32f10x_iwdg.h"
#include "stm32f10x_dbgmcu.h"

/** 
 * @brief Initialize the watchdog timer for a specified timeout
 *
 * It is important to note that this function returns the achieved timeout 
 * for this hardware.  For hardware indendence this should be checked when 
 * scheduling updates.  Other hardware dependent details may need to be 
 * considered such as a window time which sets a minimum update time, 
 * and this function should return a recommended delay for clearing.  
 *
 * For the STM32 nominal clock rate is 32 khz, but for the maximum clock rate of
 * 60 khz and a prescalar of 4 yields a clock rate of 15 khz.  The delay that is 
 * set in the watchdog assumes the nominal clock rate, but the delay for FreeRTOS
 * to use is 75% of the minimal delay.
 *
 * @param[in] delayMs The delay period in ms
 * @returns Maximum recommended delay between updates
 */
uint8_t PIOS_WDG_Init( uint8_t delayMs )
{
  uint16_t delay;
  delay = 60 / 16 * delayMs;
  if( delay > 0xfff )
    delay = 0xfff;
  DBGMCU_Config(DBGMCU_IWDG_STOP, ENABLE);  // make the watchdog stop counting in debug mode
  IWDG_WriteAccessCmd( IWDG_WriteAccess_Enable );
  IWDG_SetPrescaler( IWDG_Prescaler_16 );
  IWDG_SetReload( delay );
  IWDG_ReloadCounter();
  IWDG_Enable();  
  return delay / (60 / 16) * .75;
}

/**
 * @brief Clear the watchdog timer
 *
 * This function must be called at the appropriate delay to prevent a reset event occuring
 */
void PIOS_WDG_Clear()
{
  IWDG_ReloadCounter();
}