//***************************************************************************** // // systick.c - Driver for the SysTick timer in NVIC. // // Copyright (c) 2005-2017 Texas Instruments Incorporated. All rights reserved. // Software License Agreement // // Redistribution and use in source and binary forms, with or without // modification, are permitted provided that the following conditions // are met: // // Redistributions of source code must retain the above copyright // notice, this list of conditions and the following disclaimer. // // Redistributions in binary form must reproduce the above copyright // notice, this list of conditions and the following disclaimer in the // documentation and/or other materials provided with the // distribution. // // Neither the name of Texas Instruments Incorporated nor the names of // its contributors may be used to endorse or promote products derived // from this software without specific prior written permission. // // THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS // "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT // LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR // A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT // OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, // SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT // LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, // DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY // THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT // (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE // OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. // //***************************************************************************** //***************************************************************************** // //! \addtogroup systick_api //! @{ // //***************************************************************************** #include "types.h" #include #include #include "inc/hw_nvic.h" #include "debug.h" #include "interrupt.h" #include "systick.h" //***************************************************************************** // //! Enables the SysTick counter. //! //! This function starts the SysTick counter. If an interrupt handler has been //! registered, it is called when the SysTick counter rolls over. //! //! \note Calling this function causes the SysTick counter to (re)commence //! counting from its current value. The counter is not automatically reloaded //! with the period as specified in a previous call to SysTickPeriodSet(). If //! an immediate reload is required, the \b NVIC_ST_CURRENT register must be //! written to force the reload. Any write to this register clears the SysTick //! counter to 0 and causes a reload with the supplied period on the next //! clock. //! //! \return None. // //***************************************************************************** void SysTickEnable(void) { // // Enable SysTick. // HWREG(NVIC_ST_CTRL) |= NVIC_ST_CTRL_CLK_SRC | NVIC_ST_CTRL_ENABLE; } //***************************************************************************** // //! Disables the SysTick counter. //! //! This function stops the SysTick counter. If an interrupt handler has been //! registered, it is not called until SysTick is restarted. //! //! \return None. // //***************************************************************************** void SysTickDisable(void) { // // Disable SysTick. // HWREG(NVIC_ST_CTRL) &= ~(NVIC_ST_CTRL_ENABLE); } //***************************************************************************** // //! Registers an interrupt handler for the SysTick interrupt. //! //! \param pfnHandler is a pointer to the function to be called when the //! SysTick interrupt occurs. //! //! This function registers the handler to be called when a SysTick interrupt //! occurs. //! //! \sa IntRegister() for important information about registering interrupt //! handlers. //! //! \return None. // //***************************************************************************** void SysTickIntRegister(void (*pfnHandler)(void)) { // // Register the interrupt handler, returning an error if an error occurs. // IntRegister(FAULT_SYSTICK, pfnHandler); // // Enable the SysTick interrupt. // HWREG(NVIC_ST_CTRL) |= NVIC_ST_CTRL_INTEN; } //***************************************************************************** // //! Unregisters the interrupt handler for the SysTick interrupt. //! //! This function unregisters the handler to be called when a SysTick interrupt //! occurs. //! //! \sa IntRegister() for important information about registering interrupt //! handlers. //! //! \return None. // //***************************************************************************** void SysTickIntUnregister(void) { // // Disable the SysTick interrupt. // HWREG(NVIC_ST_CTRL) &= ~(NVIC_ST_CTRL_INTEN); // // Unregister the interrupt handler. // IntUnregister(FAULT_SYSTICK); } //***************************************************************************** // //! Enables the SysTick interrupt. //! //! This function enables the SysTick interrupt, allowing it to be //! reflected to the processor. //! //! \note The SysTick interrupt handler is not required to clear the SysTick //! interrupt source because it is cleared automatically by the NVIC when the //! interrupt handler is called. //! //! \return None. // //***************************************************************************** void SysTickIntEnable(void) { // // Enable the SysTick interrupt. // HWREG(NVIC_ST_CTRL) |= NVIC_ST_CTRL_INTEN; } //***************************************************************************** // //! Disables the SysTick interrupt. //! //! This function disables the SysTick interrupt, preventing it from being //! reflected to the processor. //! //! \return None. // //***************************************************************************** void SysTickIntDisable(void) { // // Disable the SysTick interrupt. // HWREG(NVIC_ST_CTRL) &= ~(NVIC_ST_CTRL_INTEN); } //***************************************************************************** // //! Sets the period of the SysTick counter. //! //! \param ui32Period is the number of clock ticks in each period of the //! SysTick counter and must be between 1 and 16,777,216, inclusive. //! //! This function sets the rate at which the SysTick counter wraps, which //! equates to the number of processor clocks between interrupts. //! //! \note Calling this function does not cause the SysTick counter to reload //! immediately. If an immediate reload is required, the \b NVIC_ST_CURRENT //! register must be written. Any write to this register clears the SysTick //! counter to 0 and causes a reload with the \e ui32Period supplied here on //! the next clock after SysTick is enabled. //! //! \return None. // //***************************************************************************** void SysTickPeriodSet(uint32_t ui32Period) { // // Check the arguments. // ASSERT((ui32Period > 0) && (ui32Period <= 16777216)); // // Set the period of the SysTick counter. // HWREG(NVIC_ST_RELOAD) = ui32Period - 1; } //***************************************************************************** // //! Gets the period of the SysTick counter. //! //! This function returns the rate at which the SysTick counter wraps, which //! equates to the number of processor clocks between interrupts. //! //! \return Returns the period of the SysTick counter. // //***************************************************************************** uint32_t SysTickPeriodGet(void) { // // Return the period of the SysTick counter. // return (HWREG(NVIC_ST_RELOAD) + 1); } //***************************************************************************** // //! Gets the current value of the SysTick counter. //! //! This function returns the current value of the SysTick counter, which is //! a value between the period - 1 and zero, inclusive. //! //! \return Returns the current value of the SysTick counter. // //***************************************************************************** uint32_t SysTickValueGet(void) { // // Return the current value of the SysTick counter. // return (HWREG(NVIC_ST_CURRENT)); } //***************************************************************************** // // Close the Doxygen group. //! @} // //*****************************************************************************