[maemo-developers] [maemo-developers] Maemo Alarm/Notifier Interface

[From: Igor Stoppa]

On Wed, 2006-01-11 at 11:35 -0800, ext Jason Mills wrote:
> A few items:
> 
> 0) The RTC subsystem is served off a chip known as "Retu". Most of the ASICs
> on the Nokia 770 board seem to have nice nordic names to them. :-)
> 
> 
> 1) The RTC subsystem only supports one future alarm event, and that event may
> not be more than 24h59m from "now". Maximum alarm granularity is +/-1 minute
> or so.
23h59m if memory serves me well

Only Retu can wake up the device from poweroff state at a preset time;
unfortunately this is the time resolution that it canprovide. In order
to extend alarms and events scheduling one could have the daemon
scheduling periodic wakeups (every 24h) till the real alarm is closer
than 24h.
The granularity problem could be overcome using either a sw timer or an
internal HW timer, with better resolution than 1m.
It would be programmed by the daemon, after the last wakeup and  before
reaching the scheduled time for the event.

> 
> 
> 2) The actual definition of "now" is a bit arbitrary, because of how the RTC
> synchronization works.
> 
> 
> 3) There is a functional, albeit spartan CLI utility already available to
> talk to the RTC subsystem, -and- to set/check the alarm.
> /mnt/initfs/usr/bin/retutime
> 
> 
> 4) The osso_alarm and osso_notifier daemons are missing at least from the
> 2005.51 Nokia build. No bug is currently filed against this, and I haven't
> had a chance to file one yet. I think, though am not 100% sure, that these
> two daemons are required in order to fetch the actual alarm signal from the
> RTC subsystem.
> 
> 
> -JMills
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-- 
Igor Stoppa (Nokia M - OSSO / Tampere)