[Arm-netbook] Your personal wish list for an I/O board. (Was: EOMA-68 Carrier Board Concept)

[Henrik Nordström]

fre 2013-08-16 klockan 10:21 +0100 skrev Philip Hands:

> So, does that mean that we could power the board off of two cheap-shit
> phone chargers, and survive when they inevitably catch fire?  ;-)

It means you should be able to connect backup power to the EOMA68-A20
module via the card edge µUSB contact and have it surive and continue
networking even if the I/O board power supply burns for whatever reason.

But maybe will not work too well if the I/O board +5V gets shorted to
GND. Not sure. Need to check schematics on that.

> I'm guessing that that would need some cleverness to be able to take
> power from either or both, and detect which is powered up, and perhaps some
> more cleverness to bump the voltage back up to 5v after going through
> that first stage

The AXP controller in EOMA64-A20 module have this cleverness built-in,
with automatic switching between USB or DC power (also supports two
different battery sources but not used on EOMA68-A20).

If DC power is detected then it stops drawing power from the µUSB jack.
If DC power is lost it switches back to µUSB power.

Regards
Henrik