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https://github.com/RIOT-OS/RIOT.git
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e7fbaf3815
- removed the __attribute__((naked)) from ISRs - removed ISR_ENTER() and ISR_EXIT() macros Rationale: Cortex-Mx MCUs save registers R0-R4 automatically on calling ISRs. The naked attribute tells the compiler not to save any other registers. This is fine, as long as the code in the ISR is not nested. If nested, it will use also R4 and R5, which will then lead to currupted registers on exit of the ISR. Removing the naked will fix this.
109 lines
2.0 KiB
C
109 lines
2.0 KiB
C
/*
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* Copyright (C) 2014 Freie Universität Berlin
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*
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* This file is subject to the terms and conditions of the GNU Lesser General
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* Public License v2.1. See the file LICENSE in the top level directory for more
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* details.
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*/
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/**
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* @ingroup cpu_nrf51822
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* @{
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*
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* @file rtt.c
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* @brief Real-time timer driver implementation
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*
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* @author Hauke Petersen <hauke.petersen@fu-berlin.de>
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*
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* @}
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*/
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#include <stdlib.h>
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#include <stdio.h>
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#include "cpu.h"
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#include "board.h"
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#include "sched.h"
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#include "thread.h"
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#include "periph_conf.h"
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#include "periph/rtt.h"
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/* guard file in case no RTC device was specified */
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#if RTT_NUMOF
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/*
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* callback and argument for an active alarm
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*/
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static rtt_alarm_cb_t alarm_cb;
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static void *alarm_arg;
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void rtt_init(void)
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{
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rtt_poweron();
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/* configure interrupt */
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NVIC_SetPriority(RTT_IRQ, RTT_IRQ_PRIO);
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NVIC_EnableIRQ(RTT_IRQ);
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/* set prescaler */
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RTT_DEV->PRESCALER = RTT_PRESCALER;
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/* enable the low-frequency clock */
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NRF_CLOCK->TASKS_LFCLKSTART = 1;
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/* start the actual RTT thing */
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RTT_DEV->TASKS_START = 1;
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}
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uint32_t rtt_get_counter(void)
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{
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return RTT_DEV->COUNTER;
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}
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void rtt_set_counter(uint32_t counter)
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{
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/* not supported for the NRF51822? -> could not find out how to do this */
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}
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void rtt_set_alarm(uint32_t alarm, rtt_alarm_cb_t cb, void *arg)
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{
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alarm_cb = cb;
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alarm_arg = arg;
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RTT_DEV->CC[0] = (alarm & RTT_MAX_VALUE);
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RTT_DEV->INTENSET = RTC_INTENSET_COMPARE0_Msk;
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}
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uint32_t rtt_get_alarm(void)
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{
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return RTT_DEV->CC[0];
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}
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void rtt_clear_alarm(void)
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{
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RTT_DEV->INTENCLR = RTC_INTENSET_COMPARE0_Msk;
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}
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void rtt_poweron(void)
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{
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RTT_DEV->POWER = 1;
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}
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void rtt_poweroff(void)
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{
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RTT_DEV->POWER = 0;
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}
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void RTT_ISR(void)
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{
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if (RTT_DEV->EVENTS_COMPARE[0] ==1) {
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RTT_DEV->EVENTS_COMPARE[0] = 0;
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RTT_DEV->INTENCLR = RTC_INTENSET_COMPARE0_Msk;
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alarm_cb(alarm_arg);
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}
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if (sched_context_switch_request) {
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thread_yield();
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}
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}
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#endif /* RTT_NUMOF */
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