278 lines
9.0 KiB
C
278 lines
9.0 KiB
C
//*****************************************************************************
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//
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// systick.c - Driver for the SysTick timer in NVIC.
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//
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// Copyright (c) 2005-2013 Texas Instruments Incorporated. All rights reserved.
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// Software License Agreement
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//
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// Redistribution and use in source and binary forms, with or without
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// modification, are permitted provided that the following conditions
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// are met:
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//
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// Redistributions of source code must retain the above copyright
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// notice, this list of conditions and the following disclaimer.
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//
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// Redistributions in binary form must reproduce the above copyright
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// notice, this list of conditions and the following disclaimer in the
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// documentation and/or other materials provided with the
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// distribution.
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//
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// Neither the name of Texas Instruments Incorporated nor the names of
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// its contributors may be used to endorse or promote products derived
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// from this software without specific prior written permission.
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//
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// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
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// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
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// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
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// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
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// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
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// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
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// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
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// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
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// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
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// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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//
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// This is part of revision 1.1 of the Tiva Peripheral Driver Library.
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//
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//*****************************************************************************
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//*****************************************************************************
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//
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//! \addtogroup systick_api
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//! @{
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//
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//*****************************************************************************
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#include <stdbool.h>
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#include <stdint.h>
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#include "inc/hw_ints.h"
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#include "inc/hw_nvic.h"
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#include "inc/hw_types.h"
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#include "driverlib/debug.h"
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#include "driverlib/interrupt.h"
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#include "driverlib/systick.h"
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//*****************************************************************************
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//
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//! Enables the SysTick counter.
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//!
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//! This function starts the SysTick counter. If an interrupt handler has been
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//! registered, it is called when the SysTick counter rolls over.
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//!
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//! \note Calling this function causes the SysTick counter to (re)commence
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//! counting from its current value. The counter is not automatically reloaded
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//! with the period as specified in a previous call to SysTickPeriodSet(). If
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//! an immediate reload is required, the \b NVIC_ST_CURRENT register must be
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//! written to force the reload. Any write to this register clears the SysTick
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//! counter to 0 and causes a reload with the supplied period on the next
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//! clock.
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//!
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//! \return None.
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//
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//*****************************************************************************
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void
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SysTickEnable(void)
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{
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//
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// Enable SysTick.
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//
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HWREG(NVIC_ST_CTRL) |= NVIC_ST_CTRL_CLK_SRC | NVIC_ST_CTRL_ENABLE;
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}
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//*****************************************************************************
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//
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//! Disables the SysTick counter.
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//!
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//! This function stops the SysTick counter. If an interrupt handler has been
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//! registered, it is not called until SysTick is restarted.
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//!
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//! \return None.
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//
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//*****************************************************************************
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void
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SysTickDisable(void)
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{
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//
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// Disable SysTick.
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//
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HWREG(NVIC_ST_CTRL) &= ~(NVIC_ST_CTRL_ENABLE);
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}
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//*****************************************************************************
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//
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//! Registers an interrupt handler for the SysTick interrupt.
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//!
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//! \param pfnHandler is a pointer to the function to be called when the
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//! SysTick interrupt occurs.
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//!
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//! This function registers the handler to be called when a SysTick interrupt
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//! occurs.
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//!
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//! \sa IntRegister() for important information about registering interrupt
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//! handlers.
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//!
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//! \return None.
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//
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//*****************************************************************************
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void
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SysTickIntRegister(void (*pfnHandler)(void))
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{
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//
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// Register the interrupt handler, returning an error if an error occurs.
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//
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IntRegister(FAULT_SYSTICK, pfnHandler);
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//
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// Enable the SysTick interrupt.
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//
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HWREG(NVIC_ST_CTRL) |= NVIC_ST_CTRL_INTEN;
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}
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//*****************************************************************************
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//
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//! Unregisters the interrupt handler for the SysTick interrupt.
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//!
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//! This function unregisters the handler to be called when a SysTick interrupt
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//! occurs.
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//!
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//! \sa IntRegister() for important information about registering interrupt
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//! handlers.
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//!
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//! \return None.
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//
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//*****************************************************************************
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void
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SysTickIntUnregister(void)
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{
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//
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// Disable the SysTick interrupt.
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//
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HWREG(NVIC_ST_CTRL) &= ~(NVIC_ST_CTRL_INTEN);
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//
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// Unregister the interrupt handler.
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//
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IntUnregister(FAULT_SYSTICK);
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}
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//*****************************************************************************
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//
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//! Enables the SysTick interrupt.
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//!
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//! This function enables the SysTick interrupt, allowing it to be
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//! reflected to the processor.
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//!
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//! \note The SysTick interrupt handler is not required to clear the SysTick
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//! interrupt source because it is cleared automatically by the NVIC when the
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//! interrupt handler is called.
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//!
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//! \return None.
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//
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//*****************************************************************************
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void
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SysTickIntEnable(void)
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{
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//
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// Enable the SysTick interrupt.
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//
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HWREG(NVIC_ST_CTRL) |= NVIC_ST_CTRL_INTEN;
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}
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//*****************************************************************************
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//
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//! Disables the SysTick interrupt.
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//!
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//! This function disables the SysTick interrupt, preventing it from being
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//! reflected to the processor.
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//!
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//! \return None.
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//
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//*****************************************************************************
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void
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SysTickIntDisable(void)
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{
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//
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// Disable the SysTick interrupt.
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//
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HWREG(NVIC_ST_CTRL) &= ~(NVIC_ST_CTRL_INTEN);
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}
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//*****************************************************************************
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//
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//! Sets the period of the SysTick counter.
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//!
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//! \param ui32Period is the number of clock ticks in each period of the
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//! SysTick counter and must be between 1 and 16,777,216, inclusive.
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//!
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//! This function sets the rate at which the SysTick counter wraps, which
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//! equates to the number of processor clocks between interrupts.
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//!
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//! \note Calling this function does not cause the SysTick counter to reload
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//! immediately. If an immediate reload is required, the \b NVIC_ST_CURRENT
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//! register must be written. Any write to this register clears the SysTick
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//! counter to 0 and causes a reload with the \e ui32Period supplied here on
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//! the next clock after SysTick is enabled.
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//!
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//! \return None.
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//
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//*****************************************************************************
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void
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SysTickPeriodSet(uint32_t ui32Period)
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{
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//
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// Check the arguments.
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//
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ASSERT((ui32Period > 0) && (ui32Period <= 16777216));
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//
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// Set the period of the SysTick counter.
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//
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HWREG(NVIC_ST_RELOAD) = ui32Period - 1;
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}
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//*****************************************************************************
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//
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//! Gets the period of the SysTick counter.
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//!
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//! This function returns the rate at which the SysTick counter wraps, which
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//! equates to the number of processor clocks between interrupts.
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//!
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//! \return Returns the period of the SysTick counter.
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//
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//*****************************************************************************
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uint32_t
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SysTickPeriodGet(void)
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{
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//
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// Return the period of the SysTick counter.
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//
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return(HWREG(NVIC_ST_RELOAD) + 1);
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}
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//*****************************************************************************
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//
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//! Gets the current value of the SysTick counter.
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//!
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//! This function returns the current value of the SysTick counter, which is
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//! a value between the period - 1 and zero, inclusive.
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//!
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//! \return Returns the current value of the SysTick counter.
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//
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//*****************************************************************************
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uint32_t
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SysTickValueGet(void)
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{
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//
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// Return the current value of the SysTick counter.
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//
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return(HWREG(NVIC_ST_CURRENT));
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}
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//*****************************************************************************
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//
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// Close the Doxygen group.
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//! @}
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//
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//*****************************************************************************
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