Power management

l--putt ichgeh at l--putt.de
Mon May 16 22:09:13 UTC 2011


Hi list!

Some time ago Harald suggested to create a complete phone, at least with 
minimal features. Since this hasn't been covered yet and we will have to 
rewrite some parts during RTOS porting anyway, I think we should 
consider some kind of power management:

Saving power
Having everything on and at maximum clock drains the battery _fast_! 
With the ULPD, we actually have the appropriate solution build into the 
Calypso. I guess other chipsets have something similar.
It is neat to get the timing and power sequence right. But since the 
TDMA timing is affected, Layer 1 must be aware of those clock/power 
changes or at least tolerate to be turned on and off. Does anybody right 
away have ideas how to approach this?

Charger
The C155 has a dedicated chip which you probably just have to turn on. 
On the C123, it's a bit more complex but the algorithms don't seem to be 
too complex. Has anybody tried this already?

State-of-Charge
For the usual concepts on batteryuniversity.com, a random book from the 
university lib, and some papers, we would need some means to measure the 
discharge current. No Compal phone provides this since the voltage 
regulators are connected directly to the battery. The gta02 avoids this 
with a dedicated Coulomb-counting chip. The gta01 doesn't care!? Maybe 
the battery voltage and temperature is sufficient for reasonably correct 
estimates. If not, we could try to model the current. However, this 
requires some kind of central power management that knows activated 
devices, their clocks, etc.

I would volunteer for the latter and C155-charging. However, I lack a 
C123 for tests and don't want to be responsible for exploding phones ;)
Integration of the ULPD is a bit more GSM-related. Might turn out to be 
interesting...

Cheers,
Stefan




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