Pulster fixe(s) and rework

Michael Zanetti michael_zanetti at gmx.net
Thu Mar 5 11:18:52 CET 2009

On Thursday 05 March 2009 10:38:56 Helge Hafting wrote:
> Andy Green wrote:
> > Hash: SHA1
> >
> > Somebody in the thread at some point said:
> > | On Thu, Mar 05, 2009 at 01:19:07AM +0100, Fox Mulder wrote:
> > |> Andy Green wrote:
> > |>> Johnny Tenfinger is right despite it sounds strange.  On some or all
> > |>> A5s there is no base current limit resistor on the bipolar transistor
> > |>> used to light the AUX LED.
> > |>>
> > |>> This "50mA" fault current then flows not through the LED (which has a
> > |>> reasonable series current limit resistor), but through the GPIO IO
> > |>> cell and the driver transistor base.
> > |>
> > |> If this is the problem than it really is a bad design flaw...
> > |> Maybe i should test the AUX LED on my gta02v5 how much current it uses
> > |> when it is on.
> > |
> > | Ouch. I just tested mine, and the AUX LED really uses that much (about
> > | 50mA). Does a SOP exist to fix this?
> >
> > No there's no real hardware fix that's practical.
> >
> > We could have done something extreme like PWM the enable by software in
> > FIQ ISR, but it would result in dim AUX LED even so, since the LED is
> > not seeing the excess current but just normally lit.
> >
> > It was fixed on A6, I'm afraid we just have to let it lie and not use
> > the AUX LED much as pointed out unless we're on external power.
> Now that's an idea. How about using it as a battery charging indicator?
> the orange thing can be used for other purposes then.

Thats how it is used currently in Om2008.x. Now that I know of the issue I 
think it would make sense to change the framework to also use this LED as the 
battery indicator....

I also like to use the Orange/Blue LEDs to indicate the current USB mode 
Off -> Device Mode + Networking
Orange -> Device Mode + Storage
Blue -> Host Mode
Blue+Orange -> Powered Host mode

Using Orange/Blue as a charging indicator wastes all 4 LEDs to just indicate 
charging/not charging...
The red one is useless due to this bug. The orange and blue are busy because 
of the charging indication and you can't use the violet mode because you can't 
reuse the orange and blue ones...

So, please consider changing the framework to use the red LED to indicate the 
battery charge state. 


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