454 lines
14 KiB
C
454 lines
14 KiB
C
//*****************************************************************************
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//
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// am_hal_systick.c
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//! @file
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//!
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//! @brief Functions for interfacing with the SYSTICK
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//!
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//! @addtogroup systick2 System Timer (SYSTICK)
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//! @ingroup apollo2hal
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//! @{
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//
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//*****************************************************************************
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//*****************************************************************************
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//
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// Copyright (c) 2017, Ambiq Micro
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// All rights reserved.
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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 are met:
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//
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// 1. Redistributions of source code must retain the above copyright notice,
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// this list of conditions and the following disclaimer.
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//
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// 2. 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 distribution.
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//
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// 3. Neither the name of the copyright holder nor the names of its
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// contributors may be used to endorse or promote products derived from this
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// software without specific prior written permission.
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//
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// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
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// AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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// IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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// ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE
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// LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
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// CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
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// SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
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// INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
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// CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
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// ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
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// POSSIBILITY OF SUCH DAMAGE.
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//
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// This is part of revision 1.2.11 of the AmbiqSuite Development Package.
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//
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//*****************************************************************************
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#include <stdint.h>
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#include <stdbool.h>
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#include "am_mcu_apollo.h"
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//*****************************************************************************
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//
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// Macro definitions
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//
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//*****************************************************************************
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#define SYSTICK_MAX_TICKS ((1 << 24)-1)
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#define MAX_U32 (0xffffffff)
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//*****************************************************************************
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//
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//! @brief Start the SYSTICK.
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//!
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//! This function starts the systick timer.
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//!
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//! @note This timer does not run in deep-sleep mode as it runs from the core
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//! clock, which is gated in deep-sleep. If a timer is needed in deep-sleep use
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//! one of the ctimers instead. Also to note is this timer will consume higher
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//! power than the ctimers.
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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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am_hal_systick_start(void)
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{
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//
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// Start the systick timer.
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//
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AM_REG(SYSTICK, SYSTCSR) |= AM_REG_SYSTICK_SYSTCSR_ENABLE_M;
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}
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//*****************************************************************************
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//
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//! @brief Stop the SYSTICK.
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//!
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//! This function stops the systick timer.
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//!
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//! @note This timer does not run in deep-sleep mode as it runs from the core
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//! clock, which is gated in deep-sleep. If a timer is needed in deep-sleep use
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//! one of the ctimers instead. Also to note is this timer will consume higher
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//! power than the ctimers.
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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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am_hal_systick_stop(void)
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{
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//
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// Stop the systick timer.
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//
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AM_REG(SYSTICK, SYSTCSR) &= ~AM_REG_SYSTICK_SYSTCSR_ENABLE_M;
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}
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//*****************************************************************************
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//
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//! @brief Enable the interrupt in the SYSTICK.
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//!
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//! This function enables the interupt in the systick timer.
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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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am_hal_systick_int_enable(void)
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{
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//
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// Enable the systick timer interrupt.
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//
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AM_REG(SYSTICK, SYSTCSR) |= AM_REG_SYSTICK_SYSTCSR_TICKINT_M;
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}
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//*****************************************************************************
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//
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//! @brief Disable the interrupt in the SYSTICK.
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//!
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//! This function disables the interupt in the systick timer.
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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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am_hal_systick_int_disable(void)
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{
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//
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// Disable the systick timer interrupt.
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//
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AM_REG(SYSTICK, SYSTCSR) &= ~AM_REG_SYSTICK_SYSTCSR_TICKINT_M;
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}
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//*****************************************************************************
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//
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//! @brief Reads the interrupt status.
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//!
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//! This function reads the interrupt status in the systick timer.
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//!
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//! @return the interrupt status.
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//
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//*****************************************************************************
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uint32_t
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am_hal_systick_int_status_get(void)
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{
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//
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// Return the systick timer interrupt status.
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//
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return AM_REG(SYSTICK, SYSTCSR) & AM_REG_SYSTICK_SYSTCSR_COUNTFLAG_M;
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}
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//*****************************************************************************
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//
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//! @brief Reset the interrupt in the SYSTICK.
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//!
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//! This function resets the systick timer by clearing out the configuration
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//! register.
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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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am_hal_systick_reset(void)
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{
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//
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// Reset the systick timer interrupt.
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//
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AM_REG(SYSTICK, SYSTCSR) = 0x0;
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}
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//*****************************************************************************
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//
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//! @brief Load the value into the SYSTICK.
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//!
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//! @param ui32LoadVal the desired load value for the systick. Maximum value is
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//! 0x00FF.FFFF.
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//!
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//! This function loads the desired value into the systick timer.
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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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am_hal_systick_load(uint32_t ui32LoadVal)
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{
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//
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// Write the reload register.
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//
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AM_REG(SYSTICK, SYSTRVR) = ui32LoadVal;
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}
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//*****************************************************************************
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//
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//! @brief Get the current count value in the SYSTICK.
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//!
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//! This function gets the current count value in the systick timer.
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//!
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//! @return Current count value.
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//
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//*****************************************************************************
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uint32_t
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am_hal_systick_count(void)
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{
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//
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// Return the current systick timer count value.
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//
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return AM_REG(SYSTICK, SYSTCVR);
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}
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//*****************************************************************************
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//
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//! @brief Wait the specified number of ticks.
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//!
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//! This function delays for the given number of SysTick ticks.
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//!
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//! @note If the SysTick timer is being used elsewhere, it will be corrupted
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//! by calling this function.
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//!
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//! @return 0 if successful.
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//
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//*****************************************************************************
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uint32_t
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am_hal_systick_wait_ticks(uint32_t u32Ticks)
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{
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if ( u32Ticks == 0 )
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{
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u32Ticks++; // Make sure we get the COUNTFLAG
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}
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//
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// The proper SysTick initialization sequence is: (p 4-36 of the M4 UG).
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// 1. Program reload value
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// 2. Clear current value
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// 3. Program CSR
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//
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// Set the reload value to the required number of ticks.
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//
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AM_REG(SYSTICK, SYSTRVR) = u32Ticks;
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//
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// Clear the current count.
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//
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AM_REG(SYSTICK, SYSTCVR) = 0x0;
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//
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// Set to use the processor clock, but don't cause an exception (we'll poll).
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//
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AM_REG(SYSTICK, SYSTCSR) = AM_REG_SYSTICK_SYSTCSR_ENABLE_M;
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//
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// Poll till done
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//
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while ( !(AM_REG(SYSTICK, SYSTCSR) & AM_REG_SYSTICK_SYSTCSR_COUNTFLAG_M) );
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//
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// And disable systick before exiting.
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//
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AM_REG(SYSTICK, SYSTCSR) = 0;
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return 0;
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}
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//*****************************************************************************
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//
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//! @brief Delay the specified number of microseconds.
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//!
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//! This function will use the SysTick timer to delay until the specified
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//! number of microseconds have elapsed. It uses the processor clocks and
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//! takes into account the current CORESEL setting.
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//!
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//! @note If the SysTick timer is being used elsewhere, it will be corrupted
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//! by calling this function.
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//!
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//! @return Total number of SysTick ticks delayed.
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//
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//*****************************************************************************
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uint32_t
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am_hal_systick_delay_us(uint32_t u32NumUs)
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{
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uint32_t u32ClkFreq, u32nLoops, u32Ticks, uRet;
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uint32_t u32CoreSel = AM_BFR(CLKGEN, CCTRL, CORESEL);
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u32nLoops = 1;
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switch (u32CoreSel)
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{
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//
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// We need to compute the required number of ticks. To do so and to
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// minimize divide operations, we'll use the following equation:
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// u32Ticks = (u32NumUs * HFCR_EXACT)/1000000
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// = (u32NumUs * (HFCR_EXACT * 1024)/1000000) / 1024
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// The values for the variable u32ClkFreq are computed as follows:
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// u32ClkFreq = (24390200 * 1024) / ((clksel+1)*1000000);
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// (and we'll do the remaining divide by 1024, using a shift, later).
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//
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case 0:
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u32ClkFreq = 24975;
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if ( u32NumUs > ((SYSTICK_MAX_TICKS / 24975)*1024) )
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{
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u32nLoops = (u32NumUs / ((SYSTICK_MAX_TICKS / 24975)*1024)) + 1;
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u32NumUs /= u32nLoops;
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}
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if ( u32NumUs > (MAX_U32 / 24975) )
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{
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u32Ticks = (u32NumUs >> 10) * u32ClkFreq;
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}
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else
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{
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u32Ticks = (u32NumUs * u32ClkFreq) >> 10;
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}
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break;
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case 1:
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u32ClkFreq = 12487;
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if ( u32NumUs > ((SYSTICK_MAX_TICKS / 12487)*1024) )
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{
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u32nLoops = (u32NumUs / ((SYSTICK_MAX_TICKS / 12487)*1024)) + 1;
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u32NumUs /= u32nLoops;
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}
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if ( u32NumUs > (MAX_U32 / 12487) )
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{
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u32Ticks = (u32NumUs >> 10) * u32ClkFreq;
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}
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else
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{
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u32Ticks = (u32NumUs * u32ClkFreq) >> 10;
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}
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break;
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case 2:
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u32ClkFreq = 8325;
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if ( u32NumUs > ((SYSTICK_MAX_TICKS / 8325)*1024) )
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{
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u32nLoops = (u32NumUs / ((SYSTICK_MAX_TICKS / 8325)*1024)) + 1;
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u32NumUs /= u32nLoops;
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}
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if ( u32NumUs > (MAX_U32 / 8325) )
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{
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u32Ticks = (u32NumUs >> 10) * u32ClkFreq;
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}
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else
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{
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u32Ticks = (u32NumUs * u32ClkFreq) >> 10;
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}
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break;
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case 3:
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u32ClkFreq = 6243;
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if ( u32NumUs > ((SYSTICK_MAX_TICKS / 6243)*1024) )
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{
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u32nLoops = (u32NumUs / ((SYSTICK_MAX_TICKS / 6243)*1024)) + 1;
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u32NumUs /= u32nLoops;
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}
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if ( u32NumUs > (MAX_U32 / 6243) )
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{
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u32Ticks = (u32NumUs >> 10) * u32ClkFreq;
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}
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else
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{
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u32Ticks = (u32NumUs * u32ClkFreq) >> 10;
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}
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break;
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case 4:
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u32ClkFreq = 4995;
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if ( u32NumUs > ((SYSTICK_MAX_TICKS / 4995)*1024) )
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{
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u32nLoops = (u32NumUs / ((SYSTICK_MAX_TICKS / 4995)*1024)) + 1;
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u32NumUs /= u32nLoops;
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}
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if ( u32NumUs > (MAX_U32 / 4995) )
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{
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u32Ticks = (u32NumUs >> 10) * u32ClkFreq;
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}
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else
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{
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u32Ticks = (u32NumUs * u32ClkFreq) >> 10;
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}
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break;
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case 5:
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u32ClkFreq = 4162;
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if ( u32NumUs > ((SYSTICK_MAX_TICKS / 4162)*1024) )
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{
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u32nLoops = (u32NumUs / ((SYSTICK_MAX_TICKS / 4162)*1024)) + 1;
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u32NumUs /= u32nLoops;
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}
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if ( u32NumUs > (MAX_U32 / 4162) )
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{
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u32Ticks = (u32NumUs >> 10) * u32ClkFreq;
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}
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else
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{
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u32Ticks = (u32NumUs * u32ClkFreq) >> 10;
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}
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break;
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case 6:
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u32ClkFreq = 3567;
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if ( u32NumUs > ((SYSTICK_MAX_TICKS / 3567)*1024) )
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{
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u32nLoops = (u32NumUs / ((SYSTICK_MAX_TICKS / 3567)*1024)) + 1;
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u32NumUs /= u32nLoops;
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}
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if ( u32NumUs > (MAX_U32 / 3567) )
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{
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u32Ticks = (u32NumUs >> 10) * u32ClkFreq;
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}
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else
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{
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u32Ticks = (u32NumUs * u32ClkFreq) >> 10;
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}
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break;
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case 7:
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u32ClkFreq = 3121;
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if ( u32NumUs > ((SYSTICK_MAX_TICKS / 3121)*1024) )
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{
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u32nLoops = (u32NumUs / ((SYSTICK_MAX_TICKS / 3121)*1024)) + 1;
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u32NumUs /= u32nLoops;
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}
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if ( u32NumUs > (MAX_U32 / 3121) )
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{
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u32Ticks = (u32NumUs >> 10) * u32ClkFreq;
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}
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else
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{
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u32Ticks = (u32NumUs * u32ClkFreq) >> 10;
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}
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break;
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default:
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u32Ticks = 1;
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break;
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} // switch()
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uRet = u32Ticks * u32nLoops;
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while ( u32nLoops-- )
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{
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am_hal_systick_wait_ticks(u32Ticks);
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}
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return uRet;
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}
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//*****************************************************************************
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//
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// End Doxygen group.
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//! @}
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//
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//*****************************************************************************
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