Level interrupt to atmega328, guide me please.

I make my arduino sleep in Power Down mode. And wake it up from INT and watch dog int, oviously these two interrupts are available in power Down mode.
Now i want is, such a level interrupt source which occurs in every 10, 20 minutes and wake my arduino and then after it sleeps back. I am searching for such device which generates level interrupt, or say square signal for 1, 2 seconds to wake up the atmega328.

If this post is similar to some other post then please direct me to there.

Thank You

A 555 timer?

555 timer… hmmm.
well 555 timer , with
100 uF, R1 = 10kOhms , R2 = 10 kOhms

frequency = 0.481 Hz.
Time High = 1.386 s. ← - - little higher for a level interrupt.
Cycle time 2.079 s.

but i want a gap of 10 - 20 minutes!!!

I think 555 timer will not do.

Question is, why do you not want to use the present watchdog maximum interval to perform the wakeup?

What power you save by less frequent wake-ups will be offset by the drain of the extra circuit, and you are just adding complexity to the design (as well as using up an I/O pin).

Of course a CMOS 555 will do the job, using a larger capacitor and a timing resistor of 1 or even 3 Megohms. Just beware of humidity.

Watchdog, this will give me an interval of 8 seconds.

Well, plugging up caps and res of such higher values to 555 timer circuit, is that the best solution?

I am looking for some RTC with alarm facility. But availability of such rtc, finding it bit difficult in INDIA. People are using RTC DS1307, which is without alarm feature.

Will a alarm programmable RTC will do? If yes then please educate me about that.

Thank You.

[quote author=Annim Banerjee link=topic=205917.msg1515368#msg1515368 date=1387637645] Watchdog, this will give me an interval of 8 seconds. [/quote]

Presuming your concern is to save battery power, a wakeup every eight seconds for something like ten milliseconds - enough time to increment a counter and see whether the required time has accumulated - should not take too much power.

[quote author=Annim Banerjee link=topic=205917.msg1515368#msg1515368 date=1387637645] Well, plugging up caps and res of such higher values to 555 timer circuit, is that the best solution? [/quote]

If you want an external timer, then that would be one way to go. Note I specify a CMOS 555 with a very low current consumption - a non-CMOS one would draw more current than just re-starting the ATmega as described before. An alternative is to use an oscillator/ counter such as a 4060.

[quote author=Annim Banerjee link=topic=205917.msg1515368#msg1515368 date=1387637645]

I am looking for some RTC with alarm facility. But availability of such rtc, finding it bit difficult in INDIA. People are using RTC DS1307, which is without alarm feature. [/quote]

Can't comment on this - AFAIK I only have a couple of DS1307 modules, and have not seriously experimented with them yet.

[quote author=Annim Banerjee link=topic=205917.msg1515368#msg1515368 date=1387637645] Will a alarm programmable RTC will do? If yes then please educate me about that. [/quote]

The importance of the RTC is when you want to log actual clock times, and/ or need accuracy.

  • will this 4060 osc IC give me a level interrupt to atmega328?

/thanx

It actually gives a square wave output at the determined frequency, but you can reset it.