Re: [Contiki-developers] Tmote sky low-power modes

[Jonathan L. <jo...@cs...>]

Hi Bjorn,


> A pity that the saving is so small, anyways thanks for 
> testing the code.

Yes, I thought the power drain could have been due to the flash, but hadn't
realised that it hardly uses anything (~50 micro-amps) in stand-by and that
it should be going into stand-by.


> 
> One more thing, did you check if the signature returned 
> matches M25P80_SIGNATURE?
> 

Yes I checked the signature matched, well, your code did that, I checked
that the return value of xmem_release_from_deep_power_down() was 0, and it
was.

> 
> Did you try to disable the sht11 and the light sensors?
> 

I also disabled the sht11, hardly makes any difference. I will probably try
turning off the light sensors as well, but somehow I doubt they can account
for 1.5 mA. We have some tmote-sky boards without SHT11 or S1087/S1087-1
light sensors (for routing and processing only) and their current use is
maybe 0.1mA below that of the normal tmote sky boards that do have these
sensors. 


Anyway, thanks again, if I come up with the goods I'll post my solution, in
case anyone is interested.

Cheers

	Jon


> -----Original Message-----
> From: Bjorn Gronvall [mailto:bg...@si...] 
> Sent: 10 October 2008 16:17
> To: Jonathan Lewis
> Cc: 'Contiki developer mailing list'; bg...@si...
> Subject: Re: [Contiki-developers] Tmote sky low-power modes
> 
> On Fri, 10 Oct 2008 15:34:33 +0100
> "Jonathan Lewis" <jo...@cs...> wrote:
> 
> Moi,
> 
> 
> > After looking at the M25P80 manual I suspect your code is 
> doing what 
> > it is supposed to and the change in current use is merely 
> very small. 
> > As far as I can tell from the manual, with the chip-select 
> driven high 
> > (happens at xmem_init and after spi_flash_disable) the chip will go 
> > into stand-by mode when there is nothing to do. Assuming 
> the M25P80 is 
> > going into stand-by mode then the change in current use between 
> > standby mode and deep sleep mode is only around 40__A, which is 
> > roughly what I am seeing.
> 
> A pity that the saving is so small, anyways thanks for 
> testing the code.
> 
> > So probably everything is working and thank you very much again.
> 
> One more thing, did you check if the signature returned 
> matches M25P80_SIGNATURE?
> 
> > My hunt for the guilty power drainer will continue and I'll let you 
> > know if I manage to achieve low __A current use for the TMoteSky 
> > board.
> 
> Did you try to disable the sht11 and the light sensors?
> 
> > Purely, out of interest, if it were possible to turn the chip off 
> > completely, would the line look something like P4OUT &= 
> > ~BV(FLASH_PWR); ? I merely ask, as I may want to do this for other 
> > chips on the board.
> 
> Yes, that should do the trick.
> 
> Have a nice weekend,
> /b
> 
> --
>   _     _                                           ,_______________.
> Bjorn Gronvall (Björn Grönvall)                    /_______________/|
> Swedish Institute of Computer Science              |               ||
> PO Box 1263, S-164 29 Kista, Sweden                | Schroedingers ||
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