174 lines
8.0 KiB
C
174 lines
8.0 KiB
C
/************************************************************************************//**
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* \file Source\HCS12\timer.c
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* \brief Bootloader timer driver source file.
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* \ingroup Target_HCS12
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* \internal
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*----------------------------------------------------------------------------------------
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* C O P Y R I G H T
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*----------------------------------------------------------------------------------------
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* Copyright (c) 2013 by Feaser http://www.feaser.com All rights reserved
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*
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*----------------------------------------------------------------------------------------
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* L I C E N S E
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*----------------------------------------------------------------------------------------
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* This file is part of OpenBLT. OpenBLT is free software: you can redistribute it and/or
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* modify it under the terms of the GNU General Public License as published by the Free
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* Software Foundation, either version 3 of the License, or (at your option) any later
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* version.
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*
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* OpenBLT is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY;
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* without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR
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* PURPOSE. See the GNU General Public License for more details.
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*
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* You have received a copy of the GNU General Public License along with OpenBLT. It
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* should be located in ".\Doc\license.html". If not, contact Feaser to obtain a copy.
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*
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* \endinternal
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****************************************************************************************/
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/****************************************************************************************
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* Include files
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****************************************************************************************/
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#include "boot.h" /* bootloader generic header */
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/****************************************************************************************
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* Type definitions
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****************************************************************************************/
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/** \brief Structure type with the layout of the timer related control registers. */
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typedef struct
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{
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volatile blt_int8u tios; /**< input capture/output compare select */
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volatile blt_int8u cforc; /**< compare force register */
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volatile blt_int8u oc7m; /**< output compare 7 mask register */
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volatile blt_int8u oc7d; /**< output compare 7 data register */
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volatile blt_int16u tcnt; /**< timer counter register */
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volatile blt_int8u tscr1; /**< system control register 1 */
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volatile blt_int8u ttov; /**< toggle overflow register */
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volatile blt_int8u tctl1; /**< timer control register 1 */
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volatile blt_int8u tctl2; /**< timer control register 2 */
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volatile blt_int8u tctl3; /**< timer control register 3 */
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volatile blt_int8u tctl4; /**< timer control register 4 */
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volatile blt_int8u tie; /**< interrupt enable register */
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volatile blt_int8u tscr2; /**< system control register 2 */
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volatile blt_int8u tflg1; /**< timer interrupt flag 1 */
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volatile blt_int8u tflg2; /**< timer interrupt flag 2 */
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volatile blt_int16u tc[8]; /**< input capture/output compare register n */
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} tTimerRegs; /**< timer related registers */
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/****************************************************************************************
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* Macro definitions
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****************************************************************************************/
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/** \brief Base address for the timer related control registers. */
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#define TIMER_REGS_BASE_ADDRESS (0x0040)
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/** \brief Macro for accessing the flash related control registers. */
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#define TIMER ((volatile tTimerRegs *)TIMER_REGS_BASE_ADDRESS)
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/** \brief Number of free running counter ticks in one millisecond. */
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#define TIMER_COUNTS_PER_MS (BOOT_CPU_SYSTEM_SPEED_KHZ)
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/****************************************************************************************
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* Local data declarations
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****************************************************************************************/
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/** \brief Local variable for storing the number of milliseconds that have elapsed since
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* startup.
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*/
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static blt_int32u millisecond_counter;
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/****************************************************************************************
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* Register definitions
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****************************************************************************************/
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/** \brief TSCR1 - timer enable bit. */
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#define TEN_BIT (0x80)
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/** \brief TIOS - channel 0 ic/oc configuration bit. */
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#define IOS0_BIT (0x01)
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/** \brief TFLG1 - channel 0 ic/oc event flag bit. */
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#define C0F_BIT (0x01)
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/************************************************************************************//**
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** \brief Initializes the polling based millisecond timer driver.
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** \return none.
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**
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****************************************************************************************/
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void TimerInit(void)
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{
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/* reset the timer configuration. note that this also sets the default prescaler
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* to 1, so the free running counter runs at the same speed as the system
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* (BOOT_CPU_SYSTEM_SPEED_KHZ).
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*/
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TimerReset();
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/* configure timer channel 0 as a 1 millisecond software timer */
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TIMER->tios |= IOS0_BIT;
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/* make sure timer 0 interrupt flag is cleared */
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TIMER->tflg1 = C0F_BIT;
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/* generate output compare event in 1 milliseconds from now */
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TIMER->tc[0] = TIMER->tcnt + TIMER_COUNTS_PER_MS;
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/* enable the timer subsystem */
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TIMER->tscr1 |= TEN_BIT;
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/* reset the millisecond counter value */
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millisecond_counter = 0;
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} /*** end of TimerInit ***/
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/************************************************************************************//**
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** \brief Reset the timer by placing the timer back into it's default reset
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** configuration.
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** \return none.
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**
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****************************************************************************************/
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void TimerReset(void)
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{
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/* bring the timer subsystem back into its reset state */
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TIMER->tie = 0;
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TIMER->tscr1 = 0;
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TIMER->tscr2 = 0;
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TIMER->tios = 0;
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TIMER->ttov = 0;
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TIMER->tctl1 = 0;
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TIMER->tctl2 = 0;
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TIMER->tctl3 = 0;
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TIMER->tctl4 = 0;
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} /* end of TimerReset */
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/************************************************************************************//**
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** \brief Updates the millisecond timer.
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** \return none.
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**
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****************************************************************************************/
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void TimerUpdate(void)
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{
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/* check if the millisecond event occurred */
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if ((TIMER->tflg1 & C0F_BIT) == C0F_BIT)
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{
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/* make sure timer 0 interrupt flag is cleared */
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TIMER->tflg1 = C0F_BIT;
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/* generate output compare event in 1 milliseconds from now */
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TIMER->tc[0] += TIMER_COUNTS_PER_MS;
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/* increment the millisecond counter */
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millisecond_counter++;
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}
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} /*** end of TimerUpdate ***/
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/************************************************************************************//**
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** \brief Obtains the counter value of the millisecond timer.
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** \return Current value of the millisecond timer.
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**
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****************************************************************************************/
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blt_int32u TimerGet(void)
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{
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/* updating timer here allows this function to be called in a loop with timeout
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* detection.
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*/
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TimerUpdate();
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/* read and return the amount of milliseconds that passed since initialization */
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return millisecond_counter;
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} /*** end of TimerGet ***/
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/*********************************** end of timer.c ************************************/
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