[Arm-netbook] [flying squirrel] TODO list

[Christopher]

Sent from my iPhone

On Sep 28, 2013, at 8:26 AM, "luke.leighton" <luke.leighton at gmail.com> wrote:

> On Thu, Sep 26, 2013 at 11:16 AM, luke.leighton <luke.leighton at gmail.com> wrote:
> 
>> * find out why the AXP209 is randomly shutting off (could be floating reset?)
> 
> *sigh* this turns out to be because (AGAIN) wits-tech did not...
> AGAIN ... tell us that they'd made changes which were NOT authorised,
> to the EOMA68-A20 CPU Card schematics.
> 
> this time what they've done is wire the 5V (ACIN) directly to the
> USB-OTG line of the AXP209.
> 
> *deep breath*.... the consequences of that are that when the device
> is being powered by USB-OTG, 5V appears on the EOMA68 5V power lines.
> 
> the consequences of _that_ are that the flying squirrel I/O board
> (which has its own AXP209 and a 5V step-up regulator to turn IPSOUT
> into a stable 5.0V output) fights with the incoming 5V power... and
> loses the moment that the voltage fluctuates by even the smallest
> amount (such as the A20 doing anything resembling the slightest amount
> of processing).
> 
> if wits-tech had fucking well told me what they were doing i could
> have put in a MOSFET or other power regulator on the I/O board to cope
> with power-in as well as power-out.



I don't have time to read everything, but we are putting an FPF3040 Power Distribution/Management Switch on the MEBv2 to handle this issue. 

 
> 
> not entirely sure what to do here, i'll have to think about it.  as
> far as testing the flying squirrel is concerned i can get it working
> (in a rather painful laborious way) by disconnecting USB-OTG: i've
> verified that the CPU Card can in fact be powered by *incoming* 5V
> power from the I/O board... i might need to cut one of the micro-usb
> cables i have here and remove its 5V line or something.
> 
> l.
> 
> _______________________________________________
> arm-netbook mailing list arm-netbook at lists.phcomp.co.uk
> http://lists.phcomp.co.uk/mailman/listinfo/arm-netbook
> Send large attachments to arm-netbook at files.phcomp.co.uk