rtt.c
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/*
* Copyright (C) 2014 Freie Universität Berlin
*
* This file is subject to the terms and conditions of the GNU Lesser General
* Public License v2.1. See the file LICENSE in the top level directory for more
* details.
*/
/**
* @ingroup cpu_nrf51822
* @{
*
* @file
* @brief Real-time timer driver implementation
*
* @author Hauke Petersen <hauke.petersen@fu-berlin.de>
*
* @}
*/
#include <stdlib.h>
#include <stdio.h>
#include "cpu.h"
#include "board.h"
#include "periph_conf.h"
#include "periph/rtt.h"
/* guard file in case no RTC device was specified */
#if RTT_NUMOF
/*
* @brief Callback for the active alarm
*/
static rtt_cb_t alarm_cb;
/**
* @brief Argument for the active alarm callback
*/
static void *alarm_arg;
/**
* @brief Callback for the overflow event
*/
static rtt_cb_t overflow_cb;
/**
* @brief Argument for the overflow callback
*/
static void *overflow_arg;
void rtt_init(void)
{
rtt_poweron();
/* configure interrupt */
NVIC_SetPriority(RTT_IRQ, RTT_IRQ_PRIO);
NVIC_EnableIRQ(RTT_IRQ);
/* set prescaler */
RTT_DEV->PRESCALER = RTT_PRESCALER;
/* enable the low-frequency clock */
NRF_CLOCK->TASKS_LFCLKSTART = 1;
/* start the actual RTT thing */
RTT_DEV->TASKS_START = 1;
}
void rtt_set_overflow_cb(rtt_cb_t cb, void *arg)
{
overflow_cb = cb;
overflow_arg = arg;
RTT_DEV->INTENSET = RTC_INTENSET_OVRFLW_Msk;
}
void rtt_clear_overflow_cb(void)
{
RTT_DEV->INTENCLR = RTC_INTENCLR_OVRFLW_Msk;
}
uint32_t rtt_get_counter(void)
{
return RTT_DEV->COUNTER;
}
void rtt_set_counter(uint32_t counter)
{
(void) counter;
/* not supported for the NRF51822? -> could not find out how to do this */
}
void rtt_set_alarm(uint32_t alarm, rtt_cb_t cb, void *arg)
{
alarm_cb = cb;
alarm_arg = arg;
RTT_DEV->CC[0] = (alarm & RTT_MAX_VALUE);
RTT_DEV->INTENSET = RTC_INTENSET_COMPARE0_Msk;
}
uint32_t rtt_get_alarm(void)
{
return RTT_DEV->CC[0];
}
void rtt_clear_alarm(void)
{
RTT_DEV->INTENCLR = RTC_INTENSET_COMPARE0_Msk;
}
void rtt_poweron(void)
{
RTT_DEV->POWER = 1;
}
void rtt_poweroff(void)
{
RTT_DEV->POWER = 0;
}
void RTT_ISR(void)
{
if (RTT_DEV->EVENTS_COMPARE[0] == 1) {
RTT_DEV->EVENTS_COMPARE[0] = 0;
RTT_DEV->INTENCLR = RTC_INTENSET_COMPARE0_Msk;
alarm_cb(alarm_arg);
}
if (RTT_DEV->EVENTS_OVRFLW == 1) {
RTT_DEV->EVENTS_OVRFLW = 0;
overflow_cb(overflow_arg);
}
cortexm_isr_end();
}
#endif /* RTT_NUMOF */