3ef44bff54
Fix the reload value in the examples: to get a SysTick interrupt every N clock pulses: set reload to N-1 see http://infocenter.arm.com/help/topic/com.arm.doc.dui0552a/BGBEEJHC.html#BABGACGG
161 lines
3.9 KiB
C
161 lines
3.9 KiB
C
/*
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* This file is part of the libopencm3 project.
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*
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* Copyright (C) 2010 Thomas Otto <tommi@viadmin.org>
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* Copyright (C) 2012 Benjamin Vernoux <titanmkd@gmail.com>
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*
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* This library is free software: you can redistribute it and/or modify
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* it under the terms of the GNU Lesser General Public License as published by
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* the Free Software Foundation, either version 3 of the License, or
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* (at your option) any later version.
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*
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* This library is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU Lesser General Public License for more details.
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*
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* You should have received a copy of the GNU Lesser General Public License
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* along with this library. If not, see <http://www.gnu.org/licenses/>.
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*/
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/** @defgroup CM3_systick_file SysTick
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@ingroup CM3_files
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@brief <b>libopencm3 Cortex System Tick Timer</b>
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@version 1.0.0
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@author @htmlonly © @endhtmlonly 2010 Thomas Otto <tommi@viadmin.org>
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@date 19 August 2012
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This library supports the System Tick timer in ARM Cortex Microcontrollers.
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The System Tick timer is part of the ARM Cortex core. It is a 24 bit
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down counter that can be configured with an automatical reload value.
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LGPL License Terms @ref lgpl_license
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*/
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/**@{*/
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#include <libopencm3/cm3/systick.h>
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/*-----------------------------------------------------------------------------*/
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/** @brief SysTick Set the Automatic Reload Value.
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The counter is set to the reload value when the counter starts and after it
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reaches zero.
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@param[in] value u32. 24 bit reload value.
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*/
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void systick_set_reload(u32 value)
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{
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STK_LOAD = (value & 0x00FFFFFF);
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}
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/*-----------------------------------------------------------------------------*/
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/** @brief SysTick Read the Automatic Reload Value.
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@returns 24 bit reload value as u32.
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*/
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u32 systick_get_reload(void)
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{
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return (STK_LOAD & 0x00FFFFFF);
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}
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/*-----------------------------------------------------------------------------*/
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/** @brief Get the current SysTick counter value.
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@returns 24 bit current value as u32.
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*/
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u32 systick_get_value(void)
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{
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return (STK_VAL & 0x00FFFFFF);
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}
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/*-----------------------------------------------------------------------------*/
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/** @brief Set the SysTick Clock Source.
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The clock source can be either the AHB clock or the same clock divided by 8.
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@param[in] clocksource u8. Clock source from @ref systick_clksource.
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*/
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void systick_set_clocksource(u8 clocksource)
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{
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if (clocksource < 2)
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STK_CTRL |= (clocksource << STK_CTRL_CLKSOURCE_LSB);
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}
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/*-----------------------------------------------------------------------------*/
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/** @brief Enable SysTick Interrupt.
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*/
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void systick_interrupt_enable(void)
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{
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STK_CTRL |= STK_CTRL_TICKINT;
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}
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/*-----------------------------------------------------------------------------*/
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/** @brief Disable SysTick Interrupt.
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*/
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void systick_interrupt_disable(void)
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{
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STK_CTRL &= ~STK_CTRL_TICKINT;
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}
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/*-----------------------------------------------------------------------------*/
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/** @brief Enable SysTick Counter.
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*/
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void systick_counter_enable(void)
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{
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STK_CTRL |= STK_CTRL_ENABLE;
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}
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/*-----------------------------------------------------------------------------*/
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/** @brief Disable SysTick Counter.
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*/
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void systick_counter_disable(void)
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{
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STK_CTRL &= ~STK_CTRL_ENABLE;
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}
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/*-----------------------------------------------------------------------------*/
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/** @brief SysTick Read the Counter Flag.
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The count flag is set when the timer count becomes zero, and is cleared when the
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flag is read.
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@returns Boolean if flag set.
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*/
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u8 systick_get_countflag(void)
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{
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if (STK_CTRL & STK_CTRL_COUNTFLAG)
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return 1;
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else
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return 0;
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}
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/*-----------------------------------------------------------------------------*/
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/** @brief SysTick Get Calibration Value
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@returns Current calibration value
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*/
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u32 systick_get_calib(void)
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{
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return (STK_CALIB&0x00FFFFFF);
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}
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/**@}*/
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