LED notification

Andy Green andy at openmoko.com
Thu Oct 16 17:52:10 CEST 2008

Hash: SHA1

Somebody in the thread at some point said:
| (The first message I sent does not seem to have arrived)
| On 12/10/08 18:00:55, Andy Green wrote:
|> Yes always-on MPU can deliver consistent power behaviours we can't do
|> in
|> our current way of relying on PMU.  You would basically make the PMU
|> a
|> slave of the MPU.  Stuff like debricking scheme for a programmable
|> and
|> so brickable MPU that controls the PMU... needs careful thought.
|> -Andy
| That shouldn't be a problem, because microcontrollers support in
| circuit serial programming, so just make sure we can get to those pins
| and have a doc that specifies the programming protocol for the brave.

The issue is that if we allow user-updateable MPU, it can always be
bricked.  So for example we put out a new package with some MPU update
that is broken, suddenly many devices could be bricked before we pull
it.  We definitely need some credible sequence of actions for the
end-user that can unbrick the devices.  Just telling him where some pins
are doesn't really cut it.

If the MPU is master of the CPU, then when it is bricked a lot of assets
we might otherwise call on are unavailable.  So it needs thinking
through being aware of specific capabilities of the MPU.

- -Andy
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