Power Control

Hi all,

I am developing a carrier board for the Mini210 and one of the issues I
have is power control. There doesn't appear to be a way to switch the
Mini210 running Android into a low power mode in much the same way that a
mobile phone does.

The only setting is the display going off but this only reduces the power
to around 300mA from around 550mA.

Does anyone know if in this LCD off state the system has entered a low
power state or is the backlight and LCD just powered down at this point?
There is no response to touch and hitting any key brings it back on again.

I would ideally like to have a POWER button I can press like on a mobile
phone that I can use to put the module into a lower power state. It will be
battery powered with a mains supply most of the time. The battery is mainly
to keep it alive when mains is removed. You can power it off completely at
this point if need be.

I need 2 such power modes, one is where the LCD is off but the application
continues to run (I am designing a data logger so it has to be running all
the time) and then there is the low power state where it powers down to
conserve power. This is under the users control with the power button.

I am going to dig through the source this weekend and see if I can find out
more about the power modes.

Cheers
Dave...

I can only talk from my AVR ATmega series experience.  On these chips you
can enter sleep mode where various interrupts can wake them up again.  Some
of these units , ie the Pico versions draw very small currents.  Also, you
can disable some of the peripherals or put them into low-power mode.

What on-board regulators does the mini210 use, linear or switching?  A
linear regulator running off 5 volts supplying core voltages of 1.8V or
lower would waste quite a bit of power. 

Do you need to run at the stock clock rate?  Maybe, you could reduce the
clock speed when idle (haven't tried it myself).

Thanks davef,
I've done low power with the AVR myself and of course the CPU on the
Mini210 supports this natively but as I am using Android, I need to do this
from the kernel. I am just learning how the Android OS works and digging
through the code but was hoping someone might already know.

The mini210 hardware (at least the CPU) supports many power management
options, but I don't think they are implemented in the kernel.

These features can be used to reduce power:
 - Frequency scaling (available for all 3 clock domains) (S5PV210 manual,
page 372)
 - Clock gating for many components (S5PV210 manual, page 392)

Also, there are 5 "power management" modes for conserving power (S5PV210
manual, page 417):
 - Idle mode (CPU core clock disabled)
 - Deep Idle mode (CPU core is powered off)
 - Stop mode (All clock domains are clock-gated)
 - Deep stop mode (CPU core and almost all components are power-gated)
 - Sleep mode (power is externally turned off via PMIC)

Hi Ceiliedgh,

I had forgotten about this thread having not done much with the unit for a
few months now but I am keen to get it going again as I have not completed
the battery charger and want to get the Mini210 to power right down.

On my Galaxy Note phone the processor is switched into various frequencies
depending on what it is doing. The lowest is refers to it 200Mhz and it
sits at this if on the charge and the display is off. 

When off the charger it switches to what it refers to as Deep Sleep but I
have not yet found out what that is. I just downloaded the source from
Samsung and I plan to go through this to find the relevant power down code
as the processor is very similar except it is dual core. I think power
managment is similar.

Dave...