/************************************************************************************//**
* \file Source\HCS12\timer.c
* \brief Bootloader timer driver source file.
* \ingroup Target_HCS12
* \internal
*----------------------------------------------------------------------------------------
* C O P Y R I G H T
*----------------------------------------------------------------------------------------
* Copyright (c) 2013 by Feaser http://www.feaser.com All rights reserved
*
*----------------------------------------------------------------------------------------
* L I C E N S E
*----------------------------------------------------------------------------------------
* This file is part of OpenBLT. OpenBLT 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.
*
* OpenBLT 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 OpenBLT.
* If not, see .
*
* A special exception to the GPL is included to allow you to distribute a combined work
* that includes OpenBLT without being obliged to provide the source code for any
* proprietary components. The exception text is included at the bottom of the license
* file .
*
* \endinternal
****************************************************************************************/
/****************************************************************************************
* Include files
****************************************************************************************/
#include "boot.h" /* bootloader generic header */
/****************************************************************************************
* Type definitions
****************************************************************************************/
/** \brief Structure type with the layout of the timer related control registers. */
typedef struct
{
volatile blt_int8u tios; /**< input capture/output compare select */
volatile blt_int8u cforc; /**< compare force register */
volatile blt_int8u oc7m; /**< output compare 7 mask register */
volatile blt_int8u oc7d; /**< output compare 7 data register */
volatile blt_int16u tcnt; /**< timer counter register */
volatile blt_int8u tscr1; /**< system control register 1 */
volatile blt_int8u ttov; /**< toggle overflow register */
volatile blt_int8u tctl1; /**< timer control register 1 */
volatile blt_int8u tctl2; /**< timer control register 2 */
volatile blt_int8u tctl3; /**< timer control register 3 */
volatile blt_int8u tctl4; /**< timer control register 4 */
volatile blt_int8u tie; /**< interrupt enable register */
volatile blt_int8u tscr2; /**< system control register 2 */
volatile blt_int8u tflg1; /**< timer interrupt flag 1 */
volatile blt_int8u tflg2; /**< timer interrupt flag 2 */
volatile blt_int16u tc[8]; /**< input capture/output compare register n */
} tTimerRegs; /**< timer related registers */
/****************************************************************************************
* Macro definitions
****************************************************************************************/
/** \brief Base address for the timer related control registers. */
#define TIMER_REGS_BASE_ADDRESS (0x0040)
/** \brief Macro for accessing the flash related control registers. */
#define TIMER ((volatile tTimerRegs *)TIMER_REGS_BASE_ADDRESS)
/** \brief Number of free running counter ticks in one millisecond. */
#define TIMER_COUNTS_PER_MS (BOOT_CPU_SYSTEM_SPEED_KHZ)
/****************************************************************************************
* Local data declarations
****************************************************************************************/
/** \brief Local variable for storing the number of milliseconds that have elapsed since
* startup.
*/
static blt_int32u millisecond_counter;
/****************************************************************************************
* Register definitions
****************************************************************************************/
/** \brief TSCR1 - timer enable bit. */
#define TEN_BIT (0x80)
/** \brief TIOS - channel 0 ic/oc configuration bit. */
#define IOS0_BIT (0x01)
/** \brief TFLG1 - channel 0 ic/oc event flag bit. */
#define C0F_BIT (0x01)
/************************************************************************************//**
** \brief Initializes the polling based millisecond timer driver.
** \return none.
**
****************************************************************************************/
void TimerInit(void)
{
/* reset the timer configuration. note that this also sets the default prescaler
* to 1, so the free running counter runs at the same speed as the system
* (BOOT_CPU_SYSTEM_SPEED_KHZ).
*/
TimerReset();
/* configure timer channel 0 as a 1 millisecond software timer */
TIMER->tios |= IOS0_BIT;
/* make sure timer 0 interrupt flag is cleared */
TIMER->tflg1 = C0F_BIT;
/* generate output compare event in 1 milliseconds from now */
TIMER->tc[0] = TIMER->tcnt + TIMER_COUNTS_PER_MS;
/* enable the timer subsystem */
TIMER->tscr1 |= TEN_BIT;
/* reset the millisecond counter value */
millisecond_counter = 0;
} /*** end of TimerInit ***/
/************************************************************************************//**
** \brief Reset the timer by placing the timer back into it's default reset
** configuration.
** \return none.
**
****************************************************************************************/
void TimerReset(void)
{
/* bring the timer subsystem back into its reset state */
TIMER->tie = 0;
TIMER->tscr1 = 0;
TIMER->tscr2 = 0;
TIMER->tios = 0;
TIMER->ttov = 0;
TIMER->tctl1 = 0;
TIMER->tctl2 = 0;
TIMER->tctl3 = 0;
TIMER->tctl4 = 0;
} /* end of TimerReset */
/************************************************************************************//**
** \brief Updates the millisecond timer.
** \return none.
**
****************************************************************************************/
void TimerUpdate(void)
{
/* check if the millisecond event occurred */
if ((TIMER->tflg1 & C0F_BIT) == C0F_BIT)
{
/* make sure timer 0 interrupt flag is cleared */
TIMER->tflg1 = C0F_BIT;
/* generate output compare event in 1 milliseconds from now */
TIMER->tc[0] += TIMER_COUNTS_PER_MS;
/* increment the millisecond counter */
millisecond_counter++;
}
} /*** end of TimerUpdate ***/
/************************************************************************************//**
** \brief Obtains the counter value of the millisecond timer.
** \return Current value of the millisecond timer.
**
****************************************************************************************/
blt_int32u TimerGet(void)
{
/* updating timer here allows this function to be called in a loop with timeout
* detection.
*/
TimerUpdate();
/* read and return the amount of milliseconds that passed since initialization */
return millisecond_counter;
} /*** end of TimerGet ***/
/*********************************** end of timer.c ************************************/