157 lines
6.6 KiB
C
157 lines
6.6 KiB
C
/****************************************************************************************
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| Description: bootloader timer driver source file
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| File Name: timer.c
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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) 2012 by Feaser http://www.feaser.com All rights reserved
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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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| 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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| You should have received a copy of the GNU General Public License along with OpenBLT.
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| If not, see <http://www.gnu.org/licenses/>.
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| A special exception to the GPL is included to allow you to distribute a combined work
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| that includes OpenBLT without being obliged to provide the source code for any
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| proprietary components. The exception text is included at the bottom of the license
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| file <license.html>.
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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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typedef struct
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{
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volatile blt_int32u CTRL; /* SysTick Control and Status Register */
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volatile blt_int32u LOAD; /* SysTick Reload Value Register */
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volatile blt_int32u VAL; /* SysTick Current Value Register */
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} tSysTickRegs;
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/****************************************************************************************
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* Macro definitions
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****************************************************************************************/
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#define SYSTICK_BIT_CLKSOURCE ((blt_int32u)0x00000004)
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#define SYSTICK_BIT_ENABLE ((blt_int32u)0x00000001)
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#define SYSTICK_BIT_COUNTERFLAG ((blt_int32u)0x00010000)
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/****************************************************************************************
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* Local data declarations
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****************************************************************************************/
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static blt_int16u millisecond_counter;
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/****************************************************************************************
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* Register definitions
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****************************************************************************************/
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#define SYSTICK ((tSysTickRegs *) (blt_int32u)0xE000E010)
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/****************************************************************************************
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** NAME: TimerInit
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** PARAMETER: none
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** RETURN VALUE: none
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** DESCRIPTION: Initializes the polling based millisecond timer driver.
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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 */
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TimerReset();
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/* configure the systick frequency as a 1 ms event generator */
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SYSTICK->LOAD = BOOT_CPU_SYSTEM_SPEED_KHZ - 1;
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/* reset the current counter value */
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SYSTICK->VAL = 0;
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/* select core clock as source and enable the timer */
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SYSTICK->CTRL = SYSTICK_BIT_CLKSOURCE | SYSTICK_BIT_ENABLE;
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/* reset the millisecond counter value */
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TimerSet(0);
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} /*** end of TimerInit ***/
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/****************************************************************************************
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** NAME: TimerReset
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** PARAMETER: none
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** RETURN VALUE: none
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** DESCRIPTION: Reset the timer by placing the timer back into it's default reset
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** configuration.
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**
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****************************************************************************************/
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void TimerReset(void)
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{
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/* set the systick's status and control register back into the default reset value */
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SYSTICK->CTRL = 0;
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} /* end of TimerReset */
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/****************************************************************************************
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** NAME: TimerUpdate
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** PARAMETER: none
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** RETURN VALUE: none
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** DESCRIPTION: Updates the millisecond timer.
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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 milliseond event occurred */
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if ((SYSTICK->CTRL & SYSTICK_BIT_COUNTERFLAG) != 0)
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{
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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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** NAME: TimerSet
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** PARAMETER: timer_value initialize value of the millisecond timer.
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** RETURN VALUE: none
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** DESCRIPTION: Sets the initial counter value of the millisecond timer.
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**
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****************************************************************************************/
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void TimerSet(blt_int32u timer_value)
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{
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/* set the millisecond counter value */
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millisecond_counter = timer_value;
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} /*** end of TimerSet ***/
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/****************************************************************************************
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** NAME: TimerGet
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** PARAMETER: none
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** RETURN VALUE: current value of the millisecond timer
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** DESCRIPTION: Obtains the counter 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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