[Arm-netbook] power consumption?

[lkcl luke]

On Sat, Jan 14, 2012 at 1:58 AM, lkcl luke <luke.leighton at gmail.com> wrote:
> On Sat, Jan 14, 2012 at 1:36 AM, Bari Ari <bari at onelabs.com> wrote:
>> On 01/13/2012 07:10 PM, lkcl luke wrote:
>>> hmmm... it might be worthwhile deliberately having the case at 8mm
>>> (Type III PCMCIA) so that it doesn't fit into the smaller sockets.
>>> that would make it possible to still fit the smaller cards into the
>>> (larger) sockets. other remaining issue: power. PCMCIA's 68-pin
>>> connector pins are limited to 0.5A each. if we made one of them
>>> negotiable up to 12v (after power-up and reading the I2C EEPROM), that
>>> would give almost 8 watts (12*0.5 + 5*0.5). do you think that would be
>>> enough?
>>
>> I started looking at the power pins more closely today. There are a few
>> more grounds than V+ currently. Part of this is for accommodating
>> separate analog and digital grounds.
>
>  initally i added them more for separating the high-frequency signals
> from each other.  i'm taking a bit of a flyer by having the SATA pins
> at the end, figured there'd be a shield nearby.  also i used the two
> 5V lines to separate I2C from GPIO, on the perhaps naive assumption
> that a) I2C is slow and wouldn't result in cross-talk b) GPIOs 0 and 1
> would also be low-speed.
>
>>We could swap a ground for 5V or 12V.
>
>  would that affect the stability of that power input?  if not i'd
> recommend either pin 20 or pin 54.  or both.
>
>> The GPIO's could also be configured at plugin to have a few extra 5V or
>> 12V pins by reading an eeprom or pinstraps on the card.
>
>  oh duh of course, forgot about that.  hmmm...
>
>> The larger case for Type III would keep them from getting plugged into
>> the smaller 5mm thick slots will work here again for EOMA68.
>
>  yep.
>
>> Type II cards may work in either Type II or Type III motherboards or
>> devices.
>
>  yes.
>
>> Type III motherboards or devices could default to Type II mode at
>> reset/power-on.
>
>  [initially] not sure why you'd do that... [but i do now, below].
>
>> Type III cards won't fit in Type II devices so that problem is solved.
>
>  yes.
>
>> Type III devices could be detected by the Type III mainboard or device
>> at reset/power-on by a pinstrap or eeprom on the module. The mainboard
>> could have a cheap 8 bit micro to read the pinstrap or eeprom and
>> configure a couple GPIO for use as power vs GPIO.
>
>  ah.  right, ok now i see what you're on about [above]
>
>  of course.  darn.  that's where i'd prefer it wasn't optional, and we
> picked either pin 20 or pin 54 or perhaps both to be 5V
> (non-optionally), and that was the end of it.
>
>  if it was both, that would make for 10 watts.  which is pretty damn good.
>
>  btw i'm not keen on 12V as part of the standard, *unless* you can
> show me that absolutely all EOMA68 CPU cards at the 8mm height will,
> without fail, require 12V power.
>
>  i only suggested it as an idea to get extra wattage (and then
> down-convert) but if you think we could get away with converting those
> 2 pins to 5V power that's much preferable, i think.
>
>  i'm not a great fan of "optionitis" in hardware, because it costs money :)
>
>  l.

i've added the summary (v. short) to this:

http://elinux.org/Talk:Embedded_Open_Modular_Architecture/EOMA-68