Simple (low-power) timer for MCU wakeup

Archive New Product Ideas
1

Hi all,

I may be wrong here, but anyway…

I really don’t need an RTC to wake up an MCU at a specific time, but would prefer a low-power crystal ‘something’ to generate an interrupt to

wake up any type of MCU with a signal after a predefined number of pulses, accuracy not being a problem.

I know that there are ‘modes’ for specific MCU’s to do this, but thought a generic solution might be a better approach.

Any ideas or already existing solutions folks?

2

It sounds like you know that RTC chips exist that let you set alarms. They’re reasonably low power and have a crystal. Sounds like what you want, if you’re looking for long (multiple second to 24 hour) delays.

Past that, you could program any 6 or 8 pin microcontroller to do the job for you. If you already have a low-power mode, though, just use it.

3

The tiny 10Fxxx PICs are ideal for that sort of thing.

Leon

4

Hey thanks first of all for your replies, much appreciated.

What I really meant to say was that although micros like AVRs do have low power/sleep modes (I think) they still use more current than this ‘product’.

I think this is the closest solution for me now…

http://www.maxim-ic.com/quick_view2.cfm/qv_pk/2911

I know Sparkies already have a DS1307 board, but I was hoping for a simple (and cheap) solution for datalogging - without the need for accurate time.

I may look at hacking an old watch or clock mechanism

like…

http://josepino.com/circuits/index.php? … mebase.jpc

Also, I may be wrong about MCU sleep modes and power requirements. More research required from me.

Thanks again guys.

5

phil:
What I really meant to say was that although micros like AVRs do have low power/sleep modes (I think) they still use more current than this ‘product’.

Using the low power Timer 1 on Microchip’s nanoWatt series consumes 2-3 uA. So Leon’s suggestion of the 10F or even the 16F series might do the trick.

http://www.microchip.com/stellent/group … 013819.pdf

6

Thanks for the reply riden.

Yes, even Atmel have low power chips, but I currently have various AVR

development boards of which I’d like to use one.

AT90S2312

ATmega128 (x 2)

Atiny2313 (Olimex P-20)

Atmega8535

BTW, was also thinking of a low frequency crystal with decade counter, but again, power usage is a problem.

Cheers, Phil.

Using the low power Timer 1 on Microchip’s nanoWatt series consumes 2-3 uA. So Leon’s suggestion of the 10F or even the 16F series might do the trick.

http://www.microchip.com/stellent/group … 013819.pdf