add define SLEEP_MODE to allow the user to specify the used sleep mode.

DeepSleepScheduler.h

@@ -21,6 +21,7 @@
   - #define LIBCALL_DEEP_SLEEP_SCHEDULER: This h file can only be included once within a project as it also contains the implementation.
     To use it in multiple files, define LIBCALL_DEEP_SLEEP_SCHEDULER before all include statements except one.
   All following options are to be set before the include where no LIBCALL_DEEP_SLEEP_SCHEDULER is defined.
+  - #define SLEEP_MODE: Specifies the sleep mode entered when doing deep sleep. Default is PWR_DOWN.
   - #define DEEP_SLEEP_DELAY: Prevent the CPU from entering SLEEP_MODE_PWR_DOWN for the specified amount of milli seconds after finishing the previous task.
   - #define SUPERVISION_CALLBACK: Allows to specify a callback Runnable to be called when a task runs too long. When
     the callback returns, the CPU is restarted after 15 ms by the watchdog. The callback method is called directly
@@ -44,6 +45,10 @@
 #include <util/atomic.h>
 
 // values changeable by the user
+#ifndef SLEEP_MODE
+#define SLEEP_MODE PWR_DOWN
+#endif
+
 #ifndef SUPERVISION_CALLBACK_TIMEOUT
 #define SUPERVISION_CALLBACK_TIMEOUT WDTO_1S
 #endif
@@ -675,7 +680,7 @@ inline void Scheduler::sleepIfRequired() {
     byte adcsraSave = 0;
     if (sleepMode == SLEEP) {
       noInterrupts();
-      set_sleep_mode(SLEEP_MODE_PWR_DOWN);
+      set_sleep_mode(SLEEP_MODE);
       adcsraSave = ADCSRA;
       ADCSRA = 0;  // disable ADC
       // turn off brown-out in software

README.md

@@ -100,6 +100,7 @@ You can also see them in the [Arduino Software (IDE)](https://www.arduino.cc/en/
 - [**Supervision**](https://github.com/PRosenb/DeepSleepScheduler/blob/master/examples/Supervision/Supervision.ino): Shows how to activate the task supervision in order to restart the CPU when a task takes too much time  
 - [**SupervisionWithCallback**](https://github.com/PRosenb/DeepSleepScheduler/blob/master/examples/SupervisionWithCallback/SupervisionWithCallback.ino): Shows how to activate the task supervision and get a callback when a task takes too much time  
 - [**SerialWithDeepSleepDelay**](https://github.com/PRosenb/DeepSleepScheduler/blob/master/examples/SerialWithDeepSleepDelay/SerialWithDeepSleepDelay.ino): Shows how to use `DEEP_SLEEP_DELAY` to allow serial write to finish before entering deep sleep
+- [**PwmSleep**](https://github.com/PRosenb/DeepSleepScheduler/blob/master/examples/PwmSleep/PwmSleep.ino): Shows how to use analogWrite() and still use low power mode.  
 - [**AdjustSleepTimeCorrections**](https://github.com/PRosenb/DeepSleepScheduler/blob/master/examples/AdjustSleepTimeCorrections/AdjustSleepTimeCorrections.ino): Shows how to adjust the sleep time corrections to your specific CPU
 
 ## Reference ##
@@ -264,6 +265,7 @@ enum TaskTimeout {
 - `#define LIBCALL_DEEP_SLEEP_SCHEDULER`: The header file contains definition and implementation. For that reason, it can be included once only in a project. To use it in multiple files, define `LIBCALL_DEEP_SLEEP_SCHEDULER` before all include statements except one.
 
 All following options are to be set before the include where **no** `LIBCALL_DEEP_SLEEP_SCHEDULER` is defined:
+- `#define SLEEP_MODE`: Specifies the sleep mode entered when doing deep sleep. Default is `PWR_DOWN`.
 - `#define DEEP_SLEEP_DELAY`: Prevent the CPU from entering SLEEP_MODE_PWR_DOWN for the specified amount of milliseconds after finishing the previous task.
 - `#define SUPERVISION_CALLBACK`: Allows to specify a callback `Runnable` to be called when a task runs too long. When
     the callback returns, the CPU is restarted after 15 ms by the watchdog. The callback method is called directly

examples/PwmSleep/PwmSleep.ino

@@ -0,0 +1,32 @@
+// do not use SLEEP_MODE_PWR_DOWN to prevent that
+// the asynchronous clock is stopped
+#define SLEEP_MODE SLEEP_MODE_PWR_SAVE
+// show then the CPU is active on PIN 13
+#define AWAKE_INDICATION_PIN 13
+#include <DeepSleepScheduler.h>
+
+// the PWM signal can only be used in sleep mode on
+// Arduino UNO PINs 3 and 11 because only these two
+// use an asynchronous clock that is not stopped
+// with SLEEP_MODE_PWR_SAVE
+#define PWN_PIN 3
+
+void highValue() {
+  analogWrite(PWN_PIN, 200);
+  scheduler.scheduleDelayed(lowValue, 5000);
+}
+
+void lowValue() {
+  analogWrite(PWN_PIN, 100);
+  scheduler.scheduleDelayed(highValue, 5000);
+}
+
+void setup() {
+  pinMode(PWN_PIN, OUTPUT);
+  scheduler.schedule(lowValue);
+}
+
+void loop() {
+  scheduler.execute();
+}
+