Diff: targets/TARGET_NORDIC/TARGET_NRF5/sleep.c

Revision:

149:156823d33999

Child:

150:02e0a0aed4ec

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/targets/TARGET_NORDIC/TARGET_NRF5/sleep.c	Fri Oct 28 11:17:30 2016 +0100
@@ -0,0 +1,71 @@
+/* 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
+
+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;
+
+    // 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;
+}