crashtest-r0ket/firmware/core/systick/systick.c

220 lines
7.2 KiB
C

/**************************************************************************/
/*!
@file systick.c
@author K. Townsend (microBuilder.eu)
@date 22 March 2010
@version 0.10
@section DESCRIPTION
Controls the 24-bit 'system tick' clock, which can be used as a
generic timer or to control time sharing with an embedded real-time
operating system (such as FreeRTOS).
@section Example
@code
#include "core/cpu/cpu.h"
#include "core/systick/systick.h"
void main (void)
{
cpuInit();
// Start systick timer with one tick every 10ms
systickInit(10);
while(1)
{
}
}
@endcode
@section LICENSE
Software License Agreement (BSD License)
Copyright (c) 2010, microBuilder SARL
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 holders 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 ''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 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.
*/
/**************************************************************************/
#include "systick.h"
volatile uint32_t systickTicks = 0; // 1ms tick counter
volatile uint32_t systickRollovers = 0;
void tick_wrapper(void);
/**************************************************************************/
/*!
@brief Systick interrupt handler
*/
/**************************************************************************/
void SysTick_Handler (void)
{
systickTicks++;
// Increment rollover counter
if (systickTicks == 0xFFFFFFFF) systickRollovers++;
tick_wrapper();
}
/**************************************************************************/
/*!
@brief Configures the systick timer
@param[in] ticks
The number of clock cycles between each tick of the
systick timer. for example, 'CFG_CPU_CCLK / 1000' =
1 millisecond. This value must not exceed 0x00FFFFFF.
*/
/**************************************************************************/
static uint32_t systickConfig(uint32_t ticks)
{
// Check if 'ticks' is greater than maximum value
if (ticks > SYSTICK_STRELOAD_MASK)
{
return (1);
}
// Reset counter
systickTicks = 0;
// Set reload register
SYSTICK_STRELOAD = (ticks & SYSTICK_STRELOAD_MASK) - 1;
// Load the systick counter value
SYSTICK_STCURR = 0;
// Enable systick IRQ and timer
SYSTICK_STCTRL = SYSTICK_STCTRL_CLKSOURCE |
SYSTICK_STCTRL_TICKINT |
SYSTICK_STCTRL_ENABLE;
return (0);
}
/**************************************************************************/
/*!
@brief Initialises the systick timer
@param[in] delayMs
The number of milliseconds between each tick of the systick
timer.
@note The shortest possible delay is 1 millisecond, which will
allow fine grained delays, but will cause more load on the
system than a 10mS delay. The resolution of the systick
timer needs to be balanced with the amount of processing
time you can spare. The delay should really only be set
to 1 mS if you genuinely have a need for 1mS delays,
otherwise a higher value like 5 or 10 mS is probably
more appropriate.
*/
/**************************************************************************/
void systickInit (uint32_t delayMs)
{
systickConfig ((CFG_CPU_CCLK / 1000) * delayMs);
}
/**************************************************************************/
/*!
@brief Causes a blocking delay for 'delayTicks' ticks on the
systick timer. For example: systickDelay(100) would cause
a blocking delay for 100 ticks of the systick timer.
@param[in] delayTicks
The number of systick ticks to cause a blocking delay for
@Note This function takes into account the fact that the tick
counter may eventually roll over to 0 once it reaches
0xFFFFFFFF.
*/
/**************************************************************************/
void systickDelay (uint32_t delayTicks)
{
uint32_t curTicks;
curTicks = systickTicks;
// Make sure delay is at least 1 tick in case of division, etc.
if (delayTicks == 0) delayTicks = 1;
if (curTicks > 0xFFFFFFFF - delayTicks)
{
// Rollover will occur during delay
while (systickTicks >= curTicks)
{
while (systickTicks < (delayTicks - (0xFFFFFFFF - curTicks)));
}
}
else
{
while ((systickTicks - curTicks) < delayTicks);
}
}
/**************************************************************************/
/*!
@brief Returns the current value of the systick timer counter.
This value is incremented by one every time an interrupt
fires for the systick timer.
*/
/**************************************************************************/
uint32_t systickGetTicks(void)
{
return systickTicks;
}
/**************************************************************************/
/*!
@brief Returns the current value of the systick timer rollover
counter. This value is incremented by one every time the
tick counter rolls over from 0xFFFFFFFF to 0.
*/
/**************************************************************************/
uint32_t systickGetRollovers(void)
{
return systickRollovers;
}
/**************************************************************************/
/*!
@brief Returns the approximate number of seconds that the
systick timer has been running.
*/
/**************************************************************************/
uint32_t systickGetSecondsActive(void)
{
uint32_t currentTick = systickTicks;
uint32_t rollovers = systickRollovers;
uint32_t secsActive = currentTick / (1000 / CFG_SYSTICK_DELAY_IN_MS);
secsActive += rollovers * (0xFFFFFFFF / (1000 / CFG_SYSTICK_DELAY_IN_MS));
return secsActive;
}