| //***************************************************************************** |
| // |
| // am_hal_systick.c |
| //! @file |
| //! |
| //! @brief Functions for interfacing with the SYSTICK |
| //! |
| //! @addtogroup systick2 System Timer (SYSTICK) |
| //! @ingroup apollo2hal |
| //! @{ |
| // |
| //***************************************************************************** |
| |
| //***************************************************************************** |
| // |
| // Copyright (c) 2017, Ambiq Micro |
| // All rights reserved. |
| // |
| // Redistribution and use in source and binary forms, with or without |
| // modification, are permitted provided that the following conditions are met: |
| // |
| // 1. Redistributions of source code must retain the above copyright notice, |
| // this list of conditions and the following disclaimer. |
| // |
| // 2. 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. |
| // |
| // 3. Neither the name of the copyright holder 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 HOLDER 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. |
| // |
| // This is part of revision v1.2.10-2-gea660ad-hotfix2 of the AmbiqSuite Development Package. |
| // |
| //***************************************************************************** |
| |
| #include <stdint.h> |
| #include <stdbool.h> |
| #include "am_mcu_apollo.h" |
| |
| |
| //***************************************************************************** |
| // |
| // Macro definitions |
| // |
| //***************************************************************************** |
| #define SYSTICK_MAX_TICKS ((1 << 24)-1) |
| #define MAX_U32 (0xffffffff) |
| |
| //***************************************************************************** |
| // |
| //! @brief Start the SYSTICK. |
| //! |
| //! This function starts the systick timer. |
| //! |
| //! @note This timer does not run in deep-sleep mode as it runs from the core |
| //! clock, which is gated in deep-sleep. If a timer is needed in deep-sleep use |
| //! one of the ctimers instead. Also to note is this timer will consume higher |
| //! power than the ctimers. |
| //! |
| //! @return None. |
| // |
| //***************************************************************************** |
| void |
| am_hal_systick_start(void) |
| { |
| // |
| // Start the systick timer. |
| // |
| AM_REG(SYSTICK, SYSTCSR) |= AM_REG_SYSTICK_SYSTCSR_ENABLE_M; |
| } |
| |
| //***************************************************************************** |
| // |
| //! @brief Stop the SYSTICK. |
| //! |
| //! This function stops the systick timer. |
| //! |
| //! @note This timer does not run in deep-sleep mode as it runs from the core |
| //! clock, which is gated in deep-sleep. If a timer is needed in deep-sleep use |
| //! one of the ctimers instead. Also to note is this timer will consume higher |
| //! power than the ctimers. |
| //! |
| //! @return None. |
| // |
| //***************************************************************************** |
| void |
| am_hal_systick_stop(void) |
| { |
| // |
| // Stop the systick timer. |
| // |
| AM_REG(SYSTICK, SYSTCSR) &= ~AM_REG_SYSTICK_SYSTCSR_ENABLE_M; |
| } |
| |
| //***************************************************************************** |
| // |
| //! @brief Enable the interrupt in the SYSTICK. |
| //! |
| //! This function enables the interupt in the systick timer. |
| //! |
| //! @return None. |
| // |
| //***************************************************************************** |
| void |
| am_hal_systick_int_enable(void) |
| { |
| // |
| // Enable the systick timer interrupt. |
| // |
| AM_REG(SYSTICK, SYSTCSR) |= AM_REG_SYSTICK_SYSTCSR_TICKINT_M; |
| } |
| |
| //***************************************************************************** |
| // |
| //! @brief Disable the interrupt in the SYSTICK. |
| //! |
| //! This function disables the interupt in the systick timer. |
| //! |
| //! @return None. |
| // |
| //***************************************************************************** |
| void |
| am_hal_systick_int_disable(void) |
| { |
| // |
| // Disable the systick timer interrupt. |
| // |
| AM_REG(SYSTICK, SYSTCSR) &= ~AM_REG_SYSTICK_SYSTCSR_TICKINT_M; |
| } |
| |
| //***************************************************************************** |
| // |
| //! @brief Reads the interrupt status. |
| //! |
| //! This function reads the interrupt status in the systick timer. |
| //! |
| //! @return the interrupt status. |
| // |
| //***************************************************************************** |
| uint32_t |
| am_hal_systick_int_status_get(void) |
| { |
| // |
| // Return the systick timer interrupt status. |
| // |
| return AM_REG(SYSTICK, SYSTCSR) & AM_REG_SYSTICK_SYSTCSR_COUNTFLAG_M; |
| } |
| |
| //***************************************************************************** |
| // |
| //! @brief Reset the interrupt in the SYSTICK. |
| //! |
| //! This function resets the systick timer by clearing out the configuration |
| //! register. |
| //! |
| //! @return None. |
| // |
| //***************************************************************************** |
| void |
| am_hal_systick_reset(void) |
| { |
| // |
| // Reset the systick timer interrupt. |
| // |
| AM_REG(SYSTICK, SYSTCSR) = 0x0; |
| } |
| |
| //***************************************************************************** |
| // |
| //! @brief Load the value into the SYSTICK. |
| //! |
| //! @param ui32LoadVal the desired load value for the systick. Maximum value is |
| //! 0x00FF.FFFF. |
| //! |
| //! This function loads the desired value into the systick timer. |
| //! |
| //! @return None. |
| // |
| //***************************************************************************** |
| void |
| am_hal_systick_load(uint32_t ui32LoadVal) |
| { |
| // |
| // Write the reload register. |
| // |
| AM_REG(SYSTICK, SYSTRVR) = ui32LoadVal; |
| } |
| |
| //***************************************************************************** |
| // |
| //! @brief Get the current count value in the SYSTICK. |
| //! |
| //! This function gets the current count value in the systick timer. |
| //! |
| //! @return Current count value. |
| // |
| //***************************************************************************** |
| uint32_t |
| am_hal_systick_count(void) |
| { |
| // |
| // Return the current systick timer count value. |
| // |
| return AM_REG(SYSTICK, SYSTCVR); |
| } |
| |
| //***************************************************************************** |
| // |
| //! @brief Wait the specified number of ticks. |
| //! |
| //! This function delays for the given number of SysTick ticks. |
| //! |
| //! @note If the SysTick timer is being used elsewhere, it will be corrupted |
| //! by calling this function. |
| //! |
| //! @return 0 if successful. |
| // |
| //***************************************************************************** |
| uint32_t |
| am_hal_systick_wait_ticks(uint32_t u32Ticks) |
| { |
| |
| if ( u32Ticks == 0 ) |
| { |
| u32Ticks++; // Make sure we get the COUNTFLAG |
| } |
| |
| // |
| // The proper SysTick initialization sequence is: (p 4-36 of the M4 UG). |
| // 1. Program reload value |
| // 2. Clear current value |
| // 3. Program CSR |
| // |
| // Set the reload value to the required number of ticks. |
| // |
| AM_REG(SYSTICK, SYSTRVR) = u32Ticks; |
| |
| // |
| // Clear the current count. |
| // |
| AM_REG(SYSTICK, SYSTCVR) = 0x0; |
| |
| // |
| // Set to use the processor clock, but don't cause an exception (we'll poll). |
| // |
| AM_REG(SYSTICK, SYSTCSR) = AM_REG_SYSTICK_SYSTCSR_ENABLE_M; |
| |
| // |
| // Poll till done |
| // |
| while ( !(AM_REG(SYSTICK, SYSTCSR) & AM_REG_SYSTICK_SYSTCSR_COUNTFLAG_M) ); |
| |
| // |
| // And disable systick before exiting. |
| // |
| AM_REG(SYSTICK, SYSTCSR) = 0; |
| |
| return 0; |
| } |
| |
| //***************************************************************************** |
| // |
| //! @brief Delay the specified number of microseconds. |
| //! |
| //! This function will use the SysTick timer to delay until the specified |
| //! number of microseconds have elapsed. It uses the processor clocks and |
| //! takes into account the current CORESEL setting. |
| //! |
| //! @note If the SysTick timer is being used elsewhere, it will be corrupted |
| //! by calling this function. |
| //! |
| //! @return Total number of SysTick ticks delayed. |
| // |
| //***************************************************************************** |
| uint32_t |
| am_hal_systick_delay_us(uint32_t u32NumUs) |
| { |
| uint32_t u32ClkFreq, u32nLoops, u32Ticks, uRet; |
| uint32_t u32CoreSel = AM_BFR(CLKGEN, CCTRL, CORESEL); |
| |
| u32nLoops = 1; |
| switch (u32CoreSel) |
| { |
| // |
| // We need to compute the required number of ticks. To do so and to |
| // minimize divide operations, we'll use the following equation: |
| // u32Ticks = (u32NumUs * HFCR_EXACT)/1000000 |
| // = (u32NumUs * (HFCR_EXACT * 1024)/1000000) / 1024 |
| // The values for the variable u32ClkFreq are computed as follows: |
| // u32ClkFreq = (24390200 * 1024) / ((clksel+1)*1000000); |
| // (and we'll do the remaining divide by 1024, using a shift, later). |
| // |
| case 0: |
| u32ClkFreq = 24975; |
| if ( u32NumUs > ((SYSTICK_MAX_TICKS / 24975)*1024) ) |
| { |
| u32nLoops = (u32NumUs / ((SYSTICK_MAX_TICKS / 24975)*1024)) + 1; |
| u32NumUs /= u32nLoops; |
| } |
| if ( u32NumUs > (MAX_U32 / 24975) ) |
| { |
| u32Ticks = (u32NumUs >> 10) * u32ClkFreq; |
| } |
| else |
| { |
| u32Ticks = (u32NumUs * u32ClkFreq) >> 10; |
| } |
| break; |
| case 1: |
| u32ClkFreq = 12487; |
| if ( u32NumUs > ((SYSTICK_MAX_TICKS / 12487)*1024) ) |
| { |
| u32nLoops = (u32NumUs / ((SYSTICK_MAX_TICKS / 12487)*1024)) + 1; |
| u32NumUs /= u32nLoops; |
| } |
| if ( u32NumUs > (MAX_U32 / 12487) ) |
| { |
| u32Ticks = (u32NumUs >> 10) * u32ClkFreq; |
| } |
| else |
| { |
| u32Ticks = (u32NumUs * u32ClkFreq) >> 10; |
| } |
| break; |
| case 2: |
| u32ClkFreq = 8325; |
| if ( u32NumUs > ((SYSTICK_MAX_TICKS / 8325)*1024) ) |
| { |
| u32nLoops = (u32NumUs / ((SYSTICK_MAX_TICKS / 8325)*1024)) + 1; |
| u32NumUs /= u32nLoops; |
| } |
| if ( u32NumUs > (MAX_U32 / 8325) ) |
| { |
| u32Ticks = (u32NumUs >> 10) * u32ClkFreq; |
| } |
| else |
| { |
| u32Ticks = (u32NumUs * u32ClkFreq) >> 10; |
| } |
| break; |
| case 3: |
| u32ClkFreq = 6243; |
| if ( u32NumUs > ((SYSTICK_MAX_TICKS / 6243)*1024) ) |
| { |
| u32nLoops = (u32NumUs / ((SYSTICK_MAX_TICKS / 6243)*1024)) + 1; |
| u32NumUs /= u32nLoops; |
| } |
| if ( u32NumUs > (MAX_U32 / 6243) ) |
| { |
| u32Ticks = (u32NumUs >> 10) * u32ClkFreq; |
| } |
| else |
| { |
| u32Ticks = (u32NumUs * u32ClkFreq) >> 10; |
| } |
| break; |
| case 4: |
| u32ClkFreq = 4995; |
| if ( u32NumUs > ((SYSTICK_MAX_TICKS / 4995)*1024) ) |
| { |
| u32nLoops = (u32NumUs / ((SYSTICK_MAX_TICKS / 4995)*1024)) + 1; |
| u32NumUs /= u32nLoops; |
| } |
| if ( u32NumUs > (MAX_U32 / 4995) ) |
| { |
| u32Ticks = (u32NumUs >> 10) * u32ClkFreq; |
| } |
| else |
| { |
| u32Ticks = (u32NumUs * u32ClkFreq) >> 10; |
| } |
| break; |
| case 5: |
| u32ClkFreq = 4162; |
| if ( u32NumUs > ((SYSTICK_MAX_TICKS / 4162)*1024) ) |
| { |
| u32nLoops = (u32NumUs / ((SYSTICK_MAX_TICKS / 4162)*1024)) + 1; |
| u32NumUs /= u32nLoops; |
| } |
| if ( u32NumUs > (MAX_U32 / 4162) ) |
| { |
| u32Ticks = (u32NumUs >> 10) * u32ClkFreq; |
| } |
| else |
| { |
| u32Ticks = (u32NumUs * u32ClkFreq) >> 10; |
| } |
| break; |
| case 6: |
| u32ClkFreq = 3567; |
| if ( u32NumUs > ((SYSTICK_MAX_TICKS / 3567)*1024) ) |
| { |
| u32nLoops = (u32NumUs / ((SYSTICK_MAX_TICKS / 3567)*1024)) + 1; |
| u32NumUs /= u32nLoops; |
| } |
| if ( u32NumUs > (MAX_U32 / 3567) ) |
| { |
| u32Ticks = (u32NumUs >> 10) * u32ClkFreq; |
| } |
| else |
| { |
| u32Ticks = (u32NumUs * u32ClkFreq) >> 10; |
| } |
| break; |
| case 7: |
| u32ClkFreq = 3121; |
| if ( u32NumUs > ((SYSTICK_MAX_TICKS / 3121)*1024) ) |
| { |
| u32nLoops = (u32NumUs / ((SYSTICK_MAX_TICKS / 3121)*1024)) + 1; |
| u32NumUs /= u32nLoops; |
| } |
| if ( u32NumUs > (MAX_U32 / 3121) ) |
| { |
| u32Ticks = (u32NumUs >> 10) * u32ClkFreq; |
| } |
| else |
| { |
| u32Ticks = (u32NumUs * u32ClkFreq) >> 10; |
| } |
| break; |
| default: |
| u32Ticks = 1; |
| break; |
| } // switch() |
| |
| uRet = u32Ticks * u32nLoops; |
| while ( u32nLoops-- ) |
| { |
| am_hal_systick_wait_ticks(u32Ticks); |
| } |
| |
| return uRet; |
| } |
| |
| //***************************************************************************** |
| // |
| // End Doxygen group. |
| //! @} |
| // |
| //***************************************************************************** |
