Using a library of sleeping with a combination of the WD and a physical INTERRUPT

Question

I would like to use one of the nice libraries like :

1. JEELIB
2. ENERLIB
3. SLEEP_N0M1
4. NARCOLEPTIC
5. ADAFRUITSLEEPY_DOG
6. LOW_POWER_MASTER

1. But to use a X second interval of sleeping and in the same time to enable the option of an Interrupt on pin2 that will get me out of all this sleepy mode vector if there will be interrupt ! which library is better and easier for this situation?
2. when I want more then 8 second , what is the mining of doing 2x8s when they wrote it in some of those libraries -what should it mean to do ?
3. Is there an option to enable the interrupt for a wake up from the sleep not only by a LOW_mode but also by a CHANGE_mode of the pin2 ??

Thank you very much in advanced @!

Answer 1

1. "Best" is completely subjective. I've used Narcoleptic myself. it's easy to use and somewhat limited. For the needs of my project, it served well. You'll need to review the libraries' source code and descriptions to decide which library will best serve your application.

2. The Watchdog timer has a maximum interval of 8 seconds. To sleep longer, you'll need a routine that counts enough 8 second sleeps, plus lesser sleep periods, to make up the total sleep time you want. There are other timers you can use, but not in Power Down sleep mode.

3. See section 10, "Power Management and Sleep Modes" of the ATmega328p datasheet (or the datasheet for the chip your Arduino uses). There is a table of wake-up sources for each sleep mode. It says that, except from Idle mode, only a level-triggered interrupt can wake the chip. But note that section 10.5 says a pin-change interrupt can wake the CPU. It appears that either kind can wake it but "the required level must be held long enough for the MCU to complete the wake-up to trigger the level interrupt." It does not mention the (obviously transient) pin-change interrupt. You may need to experiment.

Update:

...I cant get a sleep for more than 8 second but I can only get to a sleeping mode twice and by that to get almost a 16 second of sleeping ?

Yes, the longest Watchdog timer period is 8 seconds.

I still didn't understand if there is an easy possible to get into a sleep with a routine periods of WD wakings and in the same time enabling a physical interrupt on pin2 that works parallel ?

From my reading of the datasheet, yes, you can use both timers in parallel. But it wasn't clear to me whether a pin-change can both wake the CPU and cause an interrupt (that is, vector into your interrupt routine). A level-interrupt can, if the level is held long enough (I believe they said 4 CPU cycles would be required).