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Diff: mbed-dev/targets/TARGET_NORDIC/TARGET_NRF5/sleep.c
- Revision:
- 10:41552d038a69
--- /dev/null Thu Jan 01 00:00:00 1970 +0000 +++ b/mbed-dev/targets/TARGET_NORDIC/TARGET_NRF5/sleep.c Tue Jan 10 20:42:26 2017 +0000 @@ -0,0 +1,80 @@ +/* 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; +}