added suspendLoop for low power

Author: hathach

changelog.md

@@ -5,7 +5,8 @@
 ### Core
 
 - Make FreeRTOS run in tickless mode
-- Added systemOff() to enter hibernate mode
+- Added systemOff() to enter System Off mode
+- Added suspendLoop() to disable loop() task to further save power
 - Correct waitForEvent() function with SoftDevice enabled and disabled.
 - Added RotaryEncoder support for both Hardware and Software Encoder.
 - Ada Callback task is started along with loop task, used as worker thread to defer interrupt callback.

cores/nRF5/Arduino.h

@@ -35,6 +35,7 @@ void yield( void ) ;
 void setup( void ) ;
 void loop( void ) ;
 
+void suspendLoop(void);
 uint32_t setLoopStacksize(void);
 
 #include "WVariant.h"

cores/nRF5/main.cpp

@@ -32,6 +32,8 @@ void Bluefruit_printInfo() {}
 #include "SEGGER_SYSVIEW.h"
 #endif
 
+static TaskHandle_t  _loopHandle;
+
 
 // Weak empty variant initialization function.
 // May be redefined by variant files.
@@ -92,7 +94,6 @@ int main( void )
 #endif
 
   // Create a task for loop()
-  TaskHandle_t  _loopHandle;
   xTaskCreate( loop_task, "loop", _loopStacksize, NULL, TASK_PRIO_LOW, &_loopHandle);
 
   // Initialize callback task
@@ -105,3 +106,8 @@ int main( void )
 
   return 0;
 }
+
+void suspendLoop(void)
+{
+  vTaskSuspend(_loopHandle);
+}