Forums

Tiny AVR

Started by linnix March 12, 2012
We need a small chip with absolutely lowest power, so for the attiny4:

Top of the spec stated 200uA at 1MHz, but nothing about 125KHz.

Bottom of the spec has some chart of around 30uA at 125KHz.  Can this
be trusted?  If so, why don't they say so at the top?  I would think
that's an important marketing data.

Can it run at 32KHz like some other AVR chips?

Anyone with real experiences?  Thanks.

http://www.atmel.com/Images/doc8127.pdf
On 12 Mar., 20:52, linnix <m...@linnix.info-for.us> wrote:
> We need a small chip with absolutely lowest power, so for the attiny4: > > Top of the spec stated 200uA at 1MHz, but nothing about 125KHz. > > Bottom of the spec has some chart of around 30uA at 125KHz. =A0Can this > be trusted? =A0If so, why don't they say so at the top? =A0I would think > that's an important marketing data. > > Can it run at 32KHz like some other AVR chips? > > Anyone with real experiences? =A0Thanks. > > http://www.atmel.com/Images/doc8127.pdf
one of the first lines say fully static, so I should run at any speed down to zero -Lasse
On 12/03/12 20:52, linnix wrote:
> We need a small chip with absolutely lowest power, so for the attiny4: > > Top of the spec stated 200uA at 1MHz, but nothing about 125KHz. > > Bottom of the spec has some chart of around 30uA at 125KHz. Can this > be trusted? If so, why don't they say so at the top? I would think > that's an important marketing data. >
Usually these things are based on estimated characteristics, rather than being thoroughly statistically tested. They will typically pick a few fixed points (such as 1 MHz) and do full testing - lots of chips, lots of temperature ranges, lots of voltage ranges, and running different code - to get a figure they can guarantee. Then they will do spot tests combined with known characteristics to give estimates of the rest.
> Can it run at 32KHz like some other AVR chips?
Are you sure you want to do that? In many cases, you will get lower average power by running fast for a very short time, and spending a larger proportion of the time in deep sleep.
> > Anyone with real experiences? Thanks.
I once made a system using an AVR Tiny (I can't remember which one, but it had no ram at all - it took a little fiddling to get gcc to compile code for it) that ran from the internal RC oscillator, mostly in power-down modes. I estimated that if the button cell that powered it were perfect, I would get a lifetime of around 200 years. If that's not low enough power, then Atmel have a 4-bit series (MARC4).
> > http://www.atmel.com/Images/doc8127.pdf
"linnix" <me@linnix.info-for.us> wrote in message 
news:f4a88e98-000b-47a7-968c-9206c956aa95@r21g2000yqa.googlegroups.com...
> We need a small chip with absolutely lowest power, so for the attiny4: > > Top of the spec stated 200uA at 1MHz, but nothing about 125KHz. > > Bottom of the spec has some chart of around 30uA at 125KHz. Can this > be trusted? If so, why don't they say so at the top? I would think > that's an important marketing data. > > Can it run at 32KHz like some other AVR chips? > > Anyone with real experiences? Thanks. > > http://www.atmel.com/Images/doc8127.pdf
TINY25s will go<1uA with internal RC clock, TINY15 compatible mode...(6.4MHz ?)
linnix <me@linnix.info-for.us> wrote:

>We need a small chip with absolutely lowest power, so for the attiny4: > >Top of the spec stated 200uA at 1MHz, but nothing about 125KHz. > >Bottom of the spec has some chart of around 30uA at 125KHz. Can this >be trusted? If so, why don't they say so at the top? I would think >that's an important marketing data. > >Can it run at 32KHz like some other AVR chips? > >Anyone with real experiences? Thanks. > >http://www.atmel.com/Images/doc8127.pdf
One thing is for sure: it won't work reliable at 1.8V. This seems a better choice: http://www.ti.com/product/msp430l092 -- Failure does not prove something is impossible, failure simply indicates you are not using the right tools... nico@nctdevpuntnl (punt=.) --------------------------------------------------------------
On Mon, 12 Mar 2012 21:33:43 GMT, the renowned nico@puntnl.niks (Nico
Coesel) wrote:

>linnix <me@linnix.info-for.us> wrote: > >>We need a small chip with absolutely lowest power, so for the attiny4: >> >>Top of the spec stated 200uA at 1MHz, but nothing about 125KHz. >> >>Bottom of the spec has some chart of around 30uA at 125KHz. Can this >>be trusted? If so, why don't they say so at the top? I would think >>that's an important marketing data. >> >>Can it run at 32KHz like some other AVR chips? >> >>Anyone with real experiences? Thanks. >> >>http://www.atmel.com/Images/doc8127.pdf
ADC, low voltage trigger etc. are all very power hungry..
>One thing is for sure: it won't work reliable at 1.8V. > >This seems a better choice: >http://www.ti.com/product/msp430l092
Yes, I think the best in this category are going to be ROM-based. 8-( Best regards, Spehro Pefhany -- "it's the network..." "The Journey is the reward" speff@interlog.com Info for manufacturers: http://www.trexon.com Embedded software/hardware/analog Info for designers: http://www.speff.com
Spehro Pefhany wrote:

> On Mon, 12 Mar 2012 21:33:43 GMT, the renowned nico@puntnl.niks (Nico > Coesel) wrote: > > >>linnix <me@linnix.info-for.us> wrote: >> >> >>>We need a small chip with absolutely lowest power, so for the attiny4: >>> >>>Top of the spec stated 200uA at 1MHz, but nothing about 125KHz. >>> >>>Bottom of the spec has some chart of around 30uA at 125KHz. Can this >>>be trusted? If so, why don't they say so at the top? I would think >>>that's an important marketing data. >>> >>>Can it run at 32KHz like some other AVR chips? >>> >>>Anyone with real experiences? Thanks. >>> >>>http://www.atmel.com/Images/doc8127.pdf > > > ADC, low voltage trigger etc. are all very power hungry.. > > >>One thing is for sure: it won't work reliable at 1.8V. >> >>This seems a better choice: >>http://www.ti.com/product/msp430l092 > > > Yes, I think the best in this category are going to be ROM-based. 8-( > > > > Best regards, > Spehro Pefhany
We learn our lesson with using uC's near a magnetic mass while the uC is passing through it (moving). Care must be taken in how and where you position them. The little energy that you can endued in the circuit passing through the field (Webers) will actually hit the chip at the correct position one day and cause it to get corrupted. I suppose using Mu metals may help. We just relocated our device.. Jamie
On Mon, 12 Mar 2012 19:28:59 -0500, the renowned Jamie
<jamie_ka1lpa_not_valid_after_ka1lpa_@charter.net> wrote:

> > We learn our lesson with using uC's near a magnetic mass while the uC >is passing through it (moving). Care must be taken in how and where you >position them.
Yup.. Faraday's law of induction..
> The little energy that you can endued in the circuit >passing through the field (Webers) will actually hit the chip at the >correct position one day and cause it to get corrupted. I suppose using >Mu metals may help. We just relocated our device.. > > > Jamie
MRI? It can do a number on switchmode power supplies as well. Magnetic shielding is problematic (well, at room temperature anyway). Best regards, Spehro Pefhany -- "it's the network..." "The Journey is the reward" speff@interlog.com Info for manufacturers: http://www.trexon.com Embedded software/hardware/analog Info for designers: http://www.speff.com
On Mar 12, 1:42=A0pm, David Brown <david.br...@removethis.hesbynett.no>
wrote:
> On 12/03/12 20:52, linnix wrote: > > > We need a small chip with absolutely lowest power, so for the attiny4: > > > Top of the spec stated 200uA at 1MHz, but nothing about 125KHz. > > > Bottom of the spec has some chart of around 30uA at 125KHz. =A0Can this > > be trusted? =A0If so, why don't they say so at the top? =A0I would thin=
k
> > that's an important marketing data. > > Usually these things are based on estimated characteristics, rather than > being thoroughly statistically tested. =A0They will typically pick a few > fixed points (such as 1 MHz) and do full testing - lots of chips, lots > of temperature ranges, lots of voltage ranges, and running different > code - to get a figure they can guarantee. =A0Then they will do spot test=
s
> combined with known characteristics to give estimates of the rest.
But some other AVRs are speced to run at 32KHz. For example: atmega88 at 32KHz with 15uA @ 1.8V. For attiny4, the marketing data (first page of datasheet) only mension 1MHz and the charts cutoff at 0.1MHz. If they are using similar fab process, i would expect the same characteristics.
> > > Can it run at 32KHz like some other AVR chips? > > Are you sure you want to do that? =A0In many cases, you will get lower > average power by running fast for a very short time, and spending a > larger proportion of the time in deep sleep.
Yes, we would have to run it continuously, no sleeping.
> > > > > Anyone with real experiences? =A0Thanks. > > I once made a system using an AVR Tiny (I can't remember which one, but > it had no ram at all - it took a little fiddling to get gcc to compile > code for it) that ran from the internal RC oscillator, mostly in > power-down modes. =A0I estimated that if the button cell that powered it > were perfect, I would get a lifetime of around 200 years.
We are hoping for a few years on AA, C or D if necessary.
Spehro Pefhany wrote:

> On Mon, 12 Mar 2012 19:28:59 -0500, the renowned Jamie > <jamie_ka1lpa_not_valid_after_ka1lpa_@charter.net> wrote: > > >> We learn our lesson with using uC's near a magnetic mass while the uC >>is passing through it (moving). Care must be taken in how and where you >>position them. > > > Yup.. Faraday's law of induction.. > > >>The little energy that you can endued in the circuit >>passing through the field (Webers) will actually hit the chip at the >>correct position one day and cause it to get corrupted. I suppose using >>Mu metals may help. We just relocated our device.. >> >> >> Jamie > > > MRI? It can do a number on switchmode power supplies as well. > > Magnetic shielding is problematic (well, at room temperature anyway). > > > Best regards, > Spehro Pefhany
No, I don't work with MRI's.. These units are large eddy current clutches that slip to generate constant tension for the material that is pulling against them. We needed a way to commutate the slippage with out using slip rings, which just adds to the problem at hand. The uC circuit is mounted on the rotating mass inside of an enclosure of course, We can measure slip and then we transmit that via IR from that unit to a receiving ring off the side on a stationary mass. On smaller low current clutches we don't IR transmit the signals, we use what I guess most here would call a one wire system. The slip rings that supply the voltage to the clutch coil actually passes through my circuit first where I can modulate the line's current state to be decoded in the supply. This way, no added rings are required on the machine. The supply is PWM but never reaches 100% duty cycle, I need to read the EMF on the off cycle to get an indication if I am slipping or not. The core material will have a long enough hysteresis to where I can actually get a generate return on the signal of the rotor that is spinning. Jamie