Future Button and LED software spec

Shawn Rutledge shawn.t.rutledge at gmail.com
Thu Apr 17 03:02:22 CEST 2008

On Wed, Apr 16, 2008 at 4:42 PM, Werner Almesberger <werner at openmoko.org> wrote:
>  Right now, we could only leave them permanently on, which comes with a
>  hefty electricity bill, particularly on GTA02v5 (each LED burns about
>  150mW). In GTA02v6, this should come down to about 25mW, maybe less.

But  GTA02v5 is not going to ship is it?

>  If all we're really interested in is whether some wireless is active,
>  perhaps it should just be  blink = wlan || bt;  People can get the
>  details from the LCM.

Or just use it to indicate that an actual data transfer is occurring
(like some ethernet LEDs).

If security is implemented correctly, and power drain is also within
typical specs, it's normal for Bluetooth to be left turned on and
discoverable all the time.  (The BT SIG encourages this, but some
phone mfgs have overreacted because of past security problems, so they
have the default short timeouts for being discoverable, and in some
cases BT is actually off by default when the phone powers up, etc.  Of
course, the user should be able to turn it off manually to get the
best possible battery life, but in the absence of power problems it
doesn't hurt to have BT turned on and discoverable, and this reduces
the hassle for most of the BT use cases.)  So having it be turned on
is probably not an event that warrants an indicator LED.  Anyway it
sounds like even the optimized LED circuit takes power on the same
order of magnitude as the entire Bluetooth radio.

Some phones which have a BT LED leave it on continuously while there
is a connection, and blinking in various patterns to indicate states
like discoverable, searching, connecting, receiving a connection,
etc., and turned off completely when BT is "on" but not connected.
But for a person who uses a headset a lot, maybe the 25mW is not a
worthwhile price to pay to have the continuous glowing while the
headset is connected.  So there could be a power-saving theme which
blinks the LED only when BT packets with actual data are being
transferred (SCO, RFCOMM etc.) or only for certain profiles that seem
"eventful" (PBAP, OBEX etc.)

Likewise maybe some people would leave the WiFi connected and idle a
lot, if there was enough battery life to support that.  It would
enable some "push" services, like automatically syncing contacts every
time there is any change on your usual contact database on your PC,
and of course push email.  But those things can also be done via

>  Hmm, will there also be an indicator on the LCM that lets you get the
>  event without knowing about AUX ?

I would hope so.  There should be a GUI button or icon which appears
when there is a message, and takes you to a unified "inbox" which has
links to voicemails, emails, IMs, SMSs, system messages, etc. in
chronological order.  These are the things which would make the LED
blink too, right?

More information about the openmoko-devel mailing list