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mbed-dev/targets/TARGET_NORDIC/TARGET_NRF5/sleep.c
- Committer:
- Zaitsev
- Date:
- 2017-01-10
- Revision:
- 10:41552d038a69
File content as of revision 10:41552d038a69:
/* mbed Microcontroller Library * Copyright (c) 2006-2013 ARM Limited * * Licensed under the Apache License, Version 2.0 (the "License"); * you may not use this file except in compliance with the License. * You may obtain a copy of the License at * * http://www.apache.org/licenses/LICENSE-2.0 * * Unless required by applicable law or agreed to in writing, software * distributed under the License is distributed on an "AS IS" BASIS, * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. * See the License for the specific language governing permissions and * limitations under the License. */ #include "sleep_api.h" #include "cmsis.h" #include "mbed_interface.h" #include "softdevice_handler.h" #include "nrf_soc.h" // Mask of reserved bits of the register ICSR in the System Control Block peripheral // In this case, bits which are equal to 0 are the bits reserved in this register #define SCB_ICSR_RESERVED_BITS_MASK 0x9E43F03F #define FPU_EXCEPTION_MASK 0x0000009F void sleep(void) { // ensure debug is disconnected if semihost is enabled.... // Trigger an event when an interrupt is pending. This allows to wake up // the processor from disabled interrupts. SCB->SCR |= SCB_SCR_SEVONPEND_Msk; #ifdef NRF52 /* Clear exceptions and PendingIRQ from the FPU unit */ __set_FPSCR(__get_FPSCR() & ~(FPU_EXCEPTION_MASK)); (void) __get_FPSCR(); NVIC_ClearPendingIRQ(FPU_IRQn); #endif // If the SoftDevice is enabled, its API must be used to go to sleep. if (softdevice_handler_isEnabled()) { sd_power_mode_set(NRF_POWER_MODE_LOWPWR); sd_app_evt_wait(); } else { NRF_POWER->TASKS_LOWPWR = 1; // Note: it is not sufficient to just use WFE here, since the internal // event register may be already set from an event that occurred in the // past (like an SVC call to the SoftDevice) and in such case WFE will // just clear the register and continue execution. // Therefore, the strategy here is to first clear the event register // by using SEV/WFE pair, and then execute WFE again, unless there is // a pending interrupt. // Set an event and wake up whatsoever, this will clear the event // register from all previous events set (SVC call included) __SEV(); __WFE(); // Test if there is an interrupt pending (mask reserved regions) if (SCB->ICSR & (SCB_ICSR_RESERVED_BITS_MASK)) { // Ok, there is an interrut pending, no need to go to sleep return; } else { // next event will wakeup the CPU // If an interrupt occured between the test of SCB->ICSR and this // instruction, WFE will just not put the CPU to sleep __WFE(); } } } void deepsleep(void) { sleep(); // NRF_POWER->SYSTEMOFF=1; }