siva surendar / mbed-dev

mbed library sources. Supersedes mbed-src.

Fork of mbed-dev by mbed official

targets/TARGET_NORDIC/TARGET_NRF5/sleep.c@150:da61ba4e9755, 2016-11-25 (annotated)

Committer:
sivasuren
Date:
Fri Nov 25 07:57:40 2016 +0000
Revision:
150:da61ba4e9755
Parent:
149:156823d33999 
surendar changes

Who changed what in which revision?

UserRevisionLine numberNew contents of line
<> 149:156823d33999 1 /* mbed Microcontroller Library
<> 149:156823d33999 2 * Copyright (c) 2006-2013 ARM Limited
<> 149:156823d33999 3 *
<> 149:156823d33999 4 * Licensed under the Apache License, Version 2.0 (the "License");
<> 149:156823d33999 5 * you may not use this file except in compliance with the License.
<> 149:156823d33999 6 * You may obtain a copy of the License at
<> 149:156823d33999 7 *
<> 149:156823d33999 8 * http://www.apache.org/licenses/LICENSE-2.0
<> 149:156823d33999 9 *
<> 149:156823d33999 10 * Unless required by applicable law or agreed to in writing, software
<> 149:156823d33999 11 * distributed under the License is distributed on an "AS IS" BASIS,
<> 149:156823d33999 12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
<> 149:156823d33999 13 * See the License for the specific language governing permissions and
<> 149:156823d33999 14 * limitations under the License.
<> 149:156823d33999 15 */
<> 149:156823d33999 16 #include "sleep_api.h"
<> 149:156823d33999 17 #include "cmsis.h"
<> 149:156823d33999 18 #include "mbed_interface.h"
<> 149:156823d33999 19 #include "softdevice_handler.h"
<> 149:156823d33999 20 #include "nrf_soc.h"
<> 149:156823d33999 21
<> 149:156823d33999 22 // Mask of reserved bits of the register ICSR in the System Control Block peripheral
<> 149:156823d33999 23 // In this case, bits which are equal to 0 are the bits reserved in this register
<> 149:156823d33999 24 #define SCB_ICSR_RESERVED_BITS_MASK 0x9E43F03F
<> 149:156823d33999 25
<> 149:156823d33999 26 void sleep(void)
<> 149:156823d33999 27 {
<> 149:156823d33999 28 // ensure debug is disconnected if semihost is enabled....
<> 149:156823d33999 29
<> 149:156823d33999 30 // Trigger an event when an interrupt is pending. This allows to wake up
<> 149:156823d33999 31 // the processor from disabled interrupts.
<> 149:156823d33999 32 SCB->SCR |= SCB_SCR_SEVONPEND_Msk;
<> 149:156823d33999 33
<> 149:156823d33999 34 // If the SoftDevice is enabled, its API must be used to go to sleep.
<> 149:156823d33999 35 if (softdevice_handler_isEnabled()) {
<> 149:156823d33999 36 sd_power_mode_set(NRF_POWER_MODE_LOWPWR);
<> 149:156823d33999 37 sd_app_evt_wait();
<> 149:156823d33999 38 } else {
<> 149:156823d33999 39 NRF_POWER->TASKS_LOWPWR = 1;
<> 149:156823d33999 40
<> 149:156823d33999 41 // Note: it is not sufficient to just use WFE here, since the internal
<> 149:156823d33999 42 // event register may be already set from an event that occurred in the
<> 149:156823d33999 43 // past (like an SVC call to the SoftDevice) and in such case WFE will
<> 149:156823d33999 44 // just clear the register and continue execution.
<> 149:156823d33999 45 // Therefore, the strategy here is to first clear the event register
<> 149:156823d33999 46 // by using SEV/WFE pair, and then execute WFE again, unless there is
<> 149:156823d33999 47 // a pending interrupt.
<> 149:156823d33999 48
<> 149:156823d33999 49 // Set an event and wake up whatsoever, this will clear the event
<> 149:156823d33999 50 // register from all previous events set (SVC call included)
<> 149:156823d33999 51 __SEV();
<> 149:156823d33999 52 __WFE();
<> 149:156823d33999 53
<> 149:156823d33999 54 // Test if there is an interrupt pending (mask reserved regions)
<> 149:156823d33999 55 if (SCB->ICSR & (SCB_ICSR_RESERVED_BITS_MASK)) {
<> 149:156823d33999 56 // Ok, there is an interrut pending, no need to go to sleep
<> 149:156823d33999 57 return;
<> 149:156823d33999 58 } else {
<> 149:156823d33999 59 // next event will wakeup the CPU
<> 149:156823d33999 60 // If an interrupt occured between the test of SCB->ICSR and this
<> 149:156823d33999 61 // instruction, WFE will just not put the CPU to sleep
<> 149:156823d33999 62 __WFE();
<> 149:156823d33999 63 }
<> 149:156823d33999 64 }
<> 149:156823d33999 65 }
<> 149:156823d33999 66
<> 149:156823d33999 67 void deepsleep(void)
<> 149:156823d33999 68 {
<> 149:156823d33999 69 sleep();
<> 149:156823d33999 70 // NRF_POWER->SYSTEMOFF=1;
<> 149:156823d33999 71 }