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Subject: Re[2]: Use SLEEP instruction for longer (?) runtime
From: Uwe Freese (mail_at_uwe-freese.de)
Date: 2003-01-25


Hello Andrew,

Andrew Jamieson wrote on Saturday, January 25, 2003, 8:15:34 AM:

AJ> OK. For this build (in idle state):

AJ> No power save mode: 110mA
AJ> CPU Sleep: 98mA
AJ> CPU Stop: 95mA
AJ> CPU Standby: 81mA

AJ> Clearly, standby would be awesome if we could implement it, saving up to a
AJ> whopping 20% on the best we can currently achieve. However, the reality of

The alarm out pin (that connection I cut for my alarm mod ;) ) is
connected to an IRQ pin of the CPU. I think it could be possible to use
the RTC to wakeup the CPU from Standby.
As I understand it, Standby mode of the CPU means that it can only woken
up externally.

If would be funny to have the alarm menu in every Rockbox version for a
recorder. If the alarm mod is there, it shuts down the device, if the
alarm mod wasn't done, it sets the alarm and sets the CPU to Standby.

Is it possible to write code like this:

set_alarm(time);
CPU_STANDBY();
lcdout('now I'm on');

and add it to the code that currently shuts down the device in
apps/alarm_menu.c? Maybe the CPU stops execution after CPU_STANDBY and
wakes up because of the alarm? Or am I thinking too simple?

Bye, Uwe.



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