AVR-Chat

Hi Folks,

I've looked through the datasheet and I can't seem to find any data on
how long the chip takes to come out of standby.  I need to maximize
battery life so I envision the chip to spend a lot of time in a
power-saving mode but it needs to come back to life quickly.  Does
anybody know where to find that info?  As an aside - the MSP430
advertises it will wake-up in 6us.

Thanks,

Richard

Hi Richard,

How do you intend to wake up the MCU from Standby mode ? ie, dropping
reset low, external interrupt etc. I know that if you use an external
intterupt set to respond to a "low level" it takes 2 watchdog
oscillator cycles. a Hardware reset would be pretty much
instantaneous. I havent looked at the datasheet for the Mega32, but
have significant experience with Mega8 and 16. 

If it was critical, I would set a pin low, go to sleep, configure
things to wake up immediately after going to sleep, then set the pin
high. You can then use a good scope to have a look at the time taken.
This will give you a ballpark range, but youll need a pretty good
digital scope, preferrably with programmable trigger.

Cheers
Hein B
Auckland, New Zealand.

--- In AVR-Chat@yahoogroups.com, "Richard Cooke" <rcooke@...> wrote:

>
> Hi Folks,
> 
> I've looked through the datasheet and I can't seem to find any data on
> how long the chip takes to come out of standby.  I need to maximize
> battery life so I envision the chip to spend a lot of time in a
> power-saving mode but it needs to come back to life quickly.  Does
> anybody know where to find that info?  As an aside - the MSP430
> advertises it will wake-up in 6us.
> 
> Thanks,
> 
> Richard
>

Thanks for the info.  I'm planning on using an external interrupt to
wake things up.  I just haven't been able to glean that info from
their datasheets.

--- In AVR-Chat@yahoogroups.com, "kernels_nz" <hein@...> wrote:

>
> Hi Richard,
> 
> How do you intend to wake up the MCU from Standby mode ? ie, dropping
> reset low, external interrupt etc. I know that if you use an external
> intterupt set to respond to a "low level" it takes 2 watchdog
> oscillator cycles. a Hardware reset would be pretty much
> instantaneous. I havent looked at the datasheet for the Mega32, but
> have significant experience with Mega8 and 16. 
> 
> If it was critical, I would set a pin low, go to sleep, configure
> things to wake up immediately after going to sleep, then set the pin
> high. You can then use a good scope to have a look at the time taken.
> This will give you a ballpark range, but youll need a pretty good
> digital scope, preferrably with programmable trigger.
> 
> Cheers
> Hein B
> Auckland, New Zealand.
> 
> --- In AVR-Chat@yahoogroups.com, "Richard Cooke" <rcooke@> wrote:
> >
> > Hi Folks,
> > 
> > I've looked through the datasheet and I can't seem to find any data on
> > how long the chip takes to come out of standby.  I need to maximize
> > battery life so I envision the chip to spend a lot of time in a
> > power-saving mode but it needs to come back to life quickly.  Does
> > anybody know where to find that info?  As an aside - the MSP430
> > advertises it will wake-up in 6us.
> > 
> > Thanks,
> > 
> > Richard
> >
>

Hi Richard,

The info your looking for is on page66 of the Mega32(L) Datasheet.

It was as I thaught, 2 watchdog oscillator cycles, which is dependent
on the voltage your running at, but should be easily under 6us. 

Cheers
Hein B
Auckland, New Zealand.

--- In AVR-Chat@yahoogroups.com, "Richard Cooke" <rcooke@...> wrote:
>
> Thanks for the info.  I'm planning on using an external interrupt to
> wake things up.  I just haven't been able to glean that info from
> their datasheets.
> 
> --- In AVR-Chat@yahoogroups.com, "kernels_nz" <hein@> wrote:
> >
> > Hi Richard,
> > 
> > How do you intend to wake up the MCU from Standby mode ? ie, dropping
> > reset low, external interrupt etc. I know that if you use an external
> > intterupt set to respond to a "low level" it takes 2 watchdog
> > oscillator cycles. a Hardware reset would be pretty much
> > instantaneous. I havent looked at the datasheet for the Mega32, but
> > have significant experience with Mega8 and 16. 
> > 
> > If it was critical, I would set a pin low, go to sleep, configure
> > things to wake up immediately after going to sleep, then set the pin
> > high. You can then use a good scope to have a look at the time taken.
> > This will give you a ballpark range, but youll need a pretty good
> > digital scope, preferrably with programmable trigger.
> > 
> > Cheers
> > Hein B
> > Auckland, New Zealand.
> > 
> > --- In AVR-Chat@yahoogroups.com, "Richard Cooke" <rcooke@> wrote:
> > >
> > > Hi Folks,
> > > 
> > > I've looked through the datasheet and I can't seem to find any
data on

> > > how long the chip takes to come out of standby.  I need to maximize
> > > battery life so I envision the chip to spend a lot of time in a
> > > power-saving mode but it needs to come back to life quickly.  Does
> > > anybody know where to find that info?  As an aside - the MSP430
> > > advertises it will wake-up in 6us.
> > > 
> > > Thanks,
> > > 
> > > Richard
> > >
> >
>