Lee Kai Xuan / mbed-os

mbed-os

Fork of mbed-os by erkin yucel

targets/TARGET_NORDIC/TARGET_NRF5/sleep.c@0:f269e3021894, 2016-10-23 (annotated)

Committer:
elessair
Date:
Sun Oct 23 15:10:02 2016 +0000
Revision:
0:f269e3021894
Initial commit

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elessair 0:f269e3021894 1 /* mbed Microcontroller Library
elessair 0:f269e3021894 2 * Copyright (c) 2006-2013 ARM Limited
elessair 0:f269e3021894 3 *
elessair 0:f269e3021894 4 * Licensed under the Apache License, Version 2.0 (the "License");
elessair 0:f269e3021894 5 * you may not use this file except in compliance with the License.
elessair 0:f269e3021894 6 * You may obtain a copy of the License at
elessair 0:f269e3021894 7 *
elessair 0:f269e3021894 8 * http://www.apache.org/licenses/LICENSE-2.0
elessair 0:f269e3021894 9 *
elessair 0:f269e3021894 10 * Unless required by applicable law or agreed to in writing, software
elessair 0:f269e3021894 11 * distributed under the License is distributed on an "AS IS" BASIS,
elessair 0:f269e3021894 12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
elessair 0:f269e3021894 13 * See the License for the specific language governing permissions and
elessair 0:f269e3021894 14 * limitations under the License.
elessair 0:f269e3021894 15 */
elessair 0:f269e3021894 16 #include "sleep_api.h"
elessair 0:f269e3021894 17 #include "cmsis.h"
elessair 0:f269e3021894 18 #include "mbed_interface.h"
elessair 0:f269e3021894 19 #include "softdevice_handler.h"
elessair 0:f269e3021894 20 #include "nrf_soc.h"
elessair 0:f269e3021894 21
elessair 0:f269e3021894 22 // Mask of reserved bits of the register ICSR in the System Control Block peripheral
elessair 0:f269e3021894 23 // In this case, bits which are equal to 0 are the bits reserved in this register
elessair 0:f269e3021894 24 #define SCB_ICSR_RESERVED_BITS_MASK 0x9E43F03F
elessair 0:f269e3021894 25
elessair 0:f269e3021894 26 void sleep(void)
elessair 0:f269e3021894 27 {
elessair 0:f269e3021894 28 // ensure debug is disconnected if semihost is enabled....
elessair 0:f269e3021894 29
elessair 0:f269e3021894 30 // Trigger an event when an interrupt is pending. This allows to wake up
elessair 0:f269e3021894 31 // the processor from disabled interrupts.
elessair 0:f269e3021894 32 SCB->SCR |= SCB_SCR_SEVONPEND_Msk;
elessair 0:f269e3021894 33
elessair 0:f269e3021894 34 // If the SoftDevice is enabled, its API must be used to go to sleep.
elessair 0:f269e3021894 35 if (softdevice_handler_isEnabled()) {
elessair 0:f269e3021894 36 sd_power_mode_set(NRF_POWER_MODE_LOWPWR);
elessair 0:f269e3021894 37 sd_app_evt_wait();
elessair 0:f269e3021894 38 } else {
elessair 0:f269e3021894 39 NRF_POWER->TASKS_LOWPWR = 1;
elessair 0:f269e3021894 40
elessair 0:f269e3021894 41 // Note: it is not sufficient to just use WFE here, since the internal
elessair 0:f269e3021894 42 // event register may be already set from an event that occurred in the
elessair 0:f269e3021894 43 // past (like an SVC call to the SoftDevice) and in such case WFE will
elessair 0:f269e3021894 44 // just clear the register and continue execution.
elessair 0:f269e3021894 45 // Therefore, the strategy here is to first clear the event register
elessair 0:f269e3021894 46 // by using SEV/WFE pair, and then execute WFE again, unless there is
elessair 0:f269e3021894 47 // a pending interrupt.
elessair 0:f269e3021894 48
elessair 0:f269e3021894 49 // Set an event and wake up whatsoever, this will clear the event
elessair 0:f269e3021894 50 // register from all previous events set (SVC call included)
elessair 0:f269e3021894 51 __SEV();
elessair 0:f269e3021894 52 __WFE();
elessair 0:f269e3021894 53
elessair 0:f269e3021894 54 // Test if there is an interrupt pending (mask reserved regions)
elessair 0:f269e3021894 55 if (SCB->ICSR & (SCB_ICSR_RESERVED_BITS_MASK)) {
elessair 0:f269e3021894 56 // Ok, there is an interrut pending, no need to go to sleep
elessair 0:f269e3021894 57 return;
elessair 0:f269e3021894 58 } else {
elessair 0:f269e3021894 59 // next event will wakeup the CPU
elessair 0:f269e3021894 60 // If an interrupt occured between the test of SCB->ICSR and this
elessair 0:f269e3021894 61 // instruction, WFE will just not put the CPU to sleep
elessair 0:f269e3021894 62 __WFE();
elessair 0:f269e3021894 63 }
elessair 0:f269e3021894 64 }
elessair 0:f269e3021894 65 }
elessair 0:f269e3021894 66
elessair 0:f269e3021894 67 void deepsleep(void)
elessair 0:f269e3021894 68 {
elessair 0:f269e3021894 69 sleep();
elessair 0:f269e3021894 70 // NRF_POWER->SYSTEMOFF=1;
elessair 0:f269e3021894 71 }