354 lines
10 KiB
C
354 lines
10 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 systick1 System Timer (SYSTICK)
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//! @ingroup apollo1hal
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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) 2020, 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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// Third party software included in this distribution is subject to the
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// additional license terms as defined in the /docs/licenses directory.
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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 2.4.2 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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// 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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// Write the given value to the reload register.
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// Write the Current Value Register to clear it to 0.
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//
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AM_REG(SYSTICK, SYSTRVR) = ui32LoadVal;
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AM_REG(SYSTICK, SYSTCVR) = 0;
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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 ui32Ticks)
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{
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if ( ui32Ticks == 0 )
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{
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ui32Ticks++; // 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) = ui32Ticks;
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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 ui32NumUs)
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{
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uint32_t ui32nLoops, ui32Ticks, uRet;
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uint32_t ui32ClkFreq, ui32TicksPerMHz;
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uint32_t ui32CoreSel = AM_BFR(CLKGEN, CCTRL, CORESEL);
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ui32nLoops = 0;
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if ( (ui32CoreSel <= AM_HAL_CLKGEN_CORESEL_MAXDIV) && (ui32NumUs >= 2) )
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{
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//
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// Determine clock freq, then whether we need more than 1 iteration.
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//
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ui32ClkFreq = AM_HAL_CLKGEN_FREQ_MAX_MHZ >> ui32CoreSel;
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if ( ui32CoreSel > 1 )
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{
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ui32ClkFreq = AM_HAL_CLKGEN_FREQ_MAX_MHZ / (ui32CoreSel + 1);
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}
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ui32TicksPerMHz = SYSTICK_MAX_TICKS / ui32ClkFreq;
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if ( ui32NumUs > ui32TicksPerMHz )
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{
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//
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// Get number of required loops, as well as additional ticks.
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//
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ui32nLoops = ui32NumUs / ui32TicksPerMHz;
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ui32NumUs = ui32NumUs % ui32TicksPerMHz;
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}
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//
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// Compute the number of ticks required.
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// Allow for about 2us of call overhead.
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//
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ui32Ticks = (ui32NumUs - 2) * ui32ClkFreq;
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}
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else
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{
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ui32Ticks = 1;
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}
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uRet = (ui32nLoops * SYSTICK_MAX_TICKS) + ui32Ticks;
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while ( ui32nLoops )
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{
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am_hal_systick_wait_ticks(SYSTICK_MAX_TICKS);
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ui32nLoops--;
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}
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am_hal_systick_wait_ticks(ui32Ticks);
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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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