/* ---------------------------------------------------------------------------- */
/* Atmel Microcontroller Software Support */
/* SAM Software Package License */
/* ---------------------------------------------------------------------------- */
/* Copyright (c) 2015, Atmel Corporation */
/* */
/* All rights reserved. */
/* */
/* Redistribution and use in source and binary forms, with or without */
/* modification, are permitted provided that the following condition is met: */
/* */
/* - Redistributions of source code must retain the above copyright notice, */
/* this list of conditions and the disclaimer below. */
/* */
/* Atmel's name may not be used to endorse or promote products derived from */
/* this software without specific prior written permission. */
/* */
/* DISCLAIMER: THIS SOFTWARE IS PROVIDED BY ATMEL "AS IS" AND ANY EXPRESS OR */
/* IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF */
/* MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NON-INFRINGEMENT ARE */
/* DISCLAIMED. IN NO EVENT SHALL ATMEL 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. */
/* ---------------------------------------------------------------------------- */
/** \addtogroup rtt_module Working with RTT
* \ingroup peripherals_module
* The RTT driver provides the interface to configure and use the RTT
* peripheral.
*
* The Real-time Timer is used to count elapsed seconds.\n
* This timer is clocked by the 32kHz system clock divided by a programmable
* 16-bit value. To be accurate, it is better to use an
* external 32kHz crystal instead of the internal 32kHz RC.\n
*
* To count elapsed seconds, the user could follow these few steps:
* <ul>
* <li>Programming PTPRES in RTT_MR to feeding the timer with a 1Hz signal.</li>
* <li>Writing the bit RTTRST in RTT_MR to restart the timer with new settings.
* </li>
* </ul>
*
* An alarm can be set to happen on second by setting alarm value in RTT_AR.
* Alarm occurrence can be detected by polling or interrupt.
*
* For more accurate information, please look at the RTT section of the
* Datasheet.
*
* Related files :\n
* \ref rtt.c\n
* \ref rtt.h.\n
*/
/*@{*/
/*@}*/
/**
* \file
*
* Implementation of Real Time Timer (RTT) controller.
*
*/
/*----------------------------------------------------------------------------
* Headers
*----------------------------------------------------------------------------*/
#include "chip.h"
#include <assert.h>
/*----------------------------------------------------------------------------
* Exported functions
*----------------------------------------------------------------------------*/
/**
* \brief Changes the prescaler value of the given RTT and restarts it.
*
* \note This function disables RTT interrupt sources.
*
* \param rtt Pointer to a Rtt instance.
* \param prescaler Prescaler value for the RTT.
*/
void RTT_SetPrescaler(Rtt *rtt, uint16_t prescaler)
{
rtt->RTT_MR = (prescaler | RTT_MR_RTTRST);
}
/**
* \brief Returns the current value of the RTT timer value.
*
* \param rtt Pointer to a Rtt instance.
*/
uint32_t RTT_GetTime(Rtt *rtt)
{
return rtt->RTT_VR;
}
/**
* \brief Enables the specified RTT interrupt sources.
*
* \param rtt Pointer to a Rtt instance.
* \param sources Bitmask of interrupts to enable.
*/
void RTT_EnableIT(Rtt *rtt, uint32_t sources)
{
assert((sources & 0x0004FFFF) == 0);
rtt->RTT_MR |= sources;
}
/**
* \brief Returns the status register value of the given RTT.
*
* \param rtt Pointer to an Rtt instance.
*/
uint32_t RTT_GetStatus(Rtt *rtt)
{
return rtt->RTT_SR;
}
/**
* \brief Configures the RTT to generate an alarm at the given time.
*
* \param pRtt Pointer to an Rtt instance.
* \param time Alarm time.
*/
void RTT_SetAlarm(Rtt *pRtt, uint32_t time)
{
assert(time > 0);
pRtt->RTT_AR = time - 1;
}
