mirror of https://github.com/rusefi/openblt.git
189 lines
8.4 KiB
C
189 lines
8.4 KiB
C
/************************************************************************************//**
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* \file Source/ARMCM3_STM32F2/timer.c
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* \brief Bootloader timer driver source file.
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* \ingroup Target_ARMCM3_STM32F2
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* \internal
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*----------------------------------------------------------------------------------------
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* C O P Y R I G H T
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*----------------------------------------------------------------------------------------
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* Copyright (c) 2016 by Feaser http://www.feaser.com All rights reserved
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*
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*----------------------------------------------------------------------------------------
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* L I C E N S E
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*----------------------------------------------------------------------------------------
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* This file is part of OpenBLT. OpenBLT is free software: you can redistribute it and/or
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* modify it under the terms of the GNU General Public License as published by the Free
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* Software Foundation, either version 3 of the License, or (at your option) any later
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* version.
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*
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* OpenBLT is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY;
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* without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR
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* PURPOSE. See the GNU General Public License for more details.
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*
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* You have received a copy of the GNU General Public License along with OpenBLT. It
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* should be located in ".\Doc\license.html". If not, contact Feaser to obtain a copy.
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*
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* \endinternal
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****************************************************************************************/
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/****************************************************************************************
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* Include files
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****************************************************************************************/
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#include "boot.h" /* bootloader generic header */
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#include "stm32f2xx.h" /* STM32 CPU and HAL header */
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#include "stm32f2xx_ll_bus.h" /* STM32 LL BUS header */
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#include "stm32f2xx_ll_rcc.h" /* STM32 LL RCC header */
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/****************************************************************************************
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* Macro definitions
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****************************************************************************************/
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/** \brief Frequency of the configured timer peripheral's free running counter in Hz.
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* This shoud be 100 kHz.
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*/
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#define TIMER_COUNTER_FREQ_HZ (100000U)
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/** \brief Number of free running counter counts that equal one millisecond. */
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#define TIMER_COUNTS_PER_MS (TIMER_COUNTER_FREQ_HZ / 1000U)
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/****************************************************************************************
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* Local data declarations
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****************************************************************************************/
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/** \brief Local variable for storing the number of milliseconds that have elapsed since
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* startup.
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*/
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static blt_int32u millisecond_counter;
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/** \brief Buffer for storing the last value of the free running counter. */
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static blt_int16u free_running_counter_last;
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/************************************************************************************//**
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** \brief Initializes the polling based millisecond timer driver.
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** \attention To keep the ROM footprint low, this function aims to only use LL driver
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** inline functions.
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** \return none.
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**
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****************************************************************************************/
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void TimerInit(void)
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{
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blt_int8u tim_multiplier;
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blt_int32u pclk2_frequency;
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blt_int32u pclk2_tim_frequency;
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/* All STM32F2 derivatives support a TIM1 peripheral. Its free running counter will be
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* used to realize the polling based millisecond time reference in this module.
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* Start by enabling the periperhal.
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*/
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LL_APB2_GRP1_EnableClock(LL_APB2_GRP1_PERIPH_TIM1);
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/* The TIM1 peripheral clock is derived from PCLK2. Obtain the PCLK2 frequency. */
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pclk2_frequency = __LL_RCC_CALC_PCLK2_FREQ(SystemCoreClock, LL_RCC_GetAPB2Prescaler());
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/* According to the clock tree diagram in the RCC chapter of the reference manual,
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* the PCLK2-TIM frequency = PLCK2 * 1, when the APB2 prescaler is 1, otherwise it is
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* PCLK2 * 2.
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*/
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tim_multiplier = (LL_RCC_GetAPB2Prescaler() == LL_RCC_APB2_DIV_1) ? 1U : 2U;
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/* Obtain the PCLK2-TIM frequency. */
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pclk2_tim_frequency = pclk2_frequency * tim_multiplier;
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/* Configure the free running counter as a 16-bit upwards counter that runs at the
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* desired frequency and enable it.
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*/
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TIM1->CR1 = TIM_CR1_CEN;
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TIM1->ARR = 65535U;
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TIM1->PSC = (pclk2_tim_frequency / TIMER_COUNTER_FREQ_HZ) - 1U;
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/* Generate an update event to reload the prescaler immediately. */
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TIM1->EGR |= TIM_EGR_UG;
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/* Initialize locals. */
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millisecond_counter = 0;
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free_running_counter_last = (blt_int16u)TIM1->CNT;
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} /*** end of TimerInit ***/
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/************************************************************************************//**
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** \brief Reset the timer by placing the timer back into it's default reset
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** configuration.
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** \return none.
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**
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****************************************************************************************/
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void TimerReset(void)
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{
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/* Bring the TIM1 peripheral back into its reset state and disable its clock. */
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LL_APB2_GRP1_ForceReset(LL_APB2_GRP1_PERIPH_TIM1);
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LL_APB2_GRP1_ReleaseReset(LL_APB2_GRP1_PERIPH_TIM1);
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LL_APB2_GRP1_DisableClock(LL_APB2_GRP1_PERIPH_TIM1);
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/* Set the SysTick's registers back into the default reset value. Note that this module
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* does not use the SysTick, but HAL_Init() did initialize it.
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*/
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SysTick->CTRL = 0;
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SysTick->LOAD = 0;
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SysTick->VAL = 0;
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} /*** end of TimerReset ***/
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/************************************************************************************//**
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** \brief Updates the millisecond timer.
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** \return none.
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**
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****************************************************************************************/
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void TimerUpdate(void)
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{
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blt_int16u free_running_counter_now;
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blt_int16u delta_counts;
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blt_int16u ms_counts;
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/* Get the current value of the free running counter. */
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free_running_counter_now = (blt_int16u)TIM1->CNT;
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/* Calculate the number of counts that passed since the detection of the last
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* millisecond event. Note that this calculation also works, in case the free running
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* counter overflowed, thanks to integer math.
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*/
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delta_counts = free_running_counter_now - free_running_counter_last;
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/* Did one or more milliseconds pass since the last event? */
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if (delta_counts >= TIMER_COUNTS_PER_MS)
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{
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/* Calculate how many milliseconds passed. */
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ms_counts = delta_counts / TIMER_COUNTS_PER_MS;
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/* Update the millisecond counter. */
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millisecond_counter += ms_counts;
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/* Store the counter value of the last millisecond event, to detect the next one. */
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free_running_counter_last += (ms_counts * TIMER_COUNTS_PER_MS);
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}
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} /*** end of TimerUpdate ***/
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/************************************************************************************//**
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** \brief Obtains the counter value of the millisecond timer.
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** \return Current value of the millisecond timer.
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**
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****************************************************************************************/
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blt_int32u TimerGet(void)
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{
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/* Updating timer here allows this function to be called in a loop with timeout
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* detection.
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*/
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TimerUpdate();
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/* Read and return the amount of milliseconds that passed since initialization. */
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return millisecond_counter;
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} /*** end of TimerGet ***/
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/************************************************************************************//**
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** \brief Override for the HAL driver's GetTick() functionality. This is needed
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** because the bootloader doesn't use interrupts, but the HAL's tick
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** functionality assumes that it does. This will cause the HAL_Delay()
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** function to not work properly. As a result of this override, the HAL's
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** tick functionality works in polling mode.
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** \return Current value of the millisecond timer.
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**
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****************************************************************************************/
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uint32_t HAL_GetTick(void)
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{
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/* Link to the bootloader's 1ms timer. */
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return TimerGet();
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} /*** end of HAL_GetTick ***/
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/*********************************** end of timer.c ************************************/
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