[Arm-netbook] "[EOMA68] RFC: ADDITION OF SD/MMC TO STANDARD."

[Luke Kenneth Casson Leighton]

On Tue, Dec 24, 2013 at 8:21 AM, joem <joem at martindale-electric.co.uk> wrote:
> On Mon, 2013-12-23 at 22:16 +0000, Luke Kenneth Casson Leighton wrote:
>> On Mon, Dec 23, 2013 at 10:08 PM, Christopher Thomas
>> <christopher at firemothindustries.com> wrote:
>> >
>> >
>> > Sent from my iPhone
>> >
>> >> On Dec 23, 2013, at 3:48 PM, Luke Kenneth Casson Leighton <lkcl at lkcl.net> wrote:
>> >>
>> >> i'm giving serious consideration, even at this late phase, to adding
>> >> SD/MMC to EOMA68 by way of the GPIO pins as a multiplexing option.
>> >> this would not have any impact on the EOMA68-A20 CPU Card: in fact,
>> >> the only reason this can be considered at all is because the pins
>> >> *happen* to be multiplexed as SD/MMC and GPIO *anyway*.
>> >>
>> >> does anyone have any objections, and/or can think of any gotchas which
>> >> would prevent SD/MMC from being added as a non-optional multiplexed
>> >> option to EOMA-68?
>> >>
>> >
>> > How many of the 8 GPIO would essentially be used? (I presume 6?)
>>
>>  yes, 6.  it's no change - literally - of the EOMA68-A20 CPU Card.
>> the pinouts happen already to be multiplexed to SD/MMC (just at
>> present in "non-EOMA68-compliant" mode).  the change would be "it is
>> now mandatory that the following pins be multiplexed on GPIO [1]:
>>
>> GPIO-0: SD0-D3
>> GPIO-1: SD0-D2
>> GPIO-4: SD0-CMD
>> GPIO-5: SD0-CLK
>> GPIO-6: SD0-D0
>> GPIO-7: SD0-D1
>>
>> l.
>>
>> [1] from http://rhombus-tech.net/allwinner_a10/orders/ - the section
>> on "Features".  these pins were originally selected because they have
>> a secondary multiplex functional mapping to JTAG, but also because of
>> the *tertiary* multiplex functional mapping to SD/MMC.
>
>
> My thoughts were to add an high pin count
> FPC somewhere to get more pins out
> than limit the box to 68 pins.

 next revision.  we need to sell units first.  or someone needs to
provide the $10k NREs to be able to have the first EOMA68-A20 CPU card
layout completely redesigned.  but even then, an FPC is not going to
be part of the EOMA68 specification because the EOMA68 specification
is a mass-volume specification where the units are sold with a sealed
metal shield around them.

 l.