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*/ | |
/** \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; | |
} |