I believe the best way to answer all but the last question is to throw
open the schematic to a netMMC, which I am doing as I send this.
Re: "stack" of MMC Cards, it may be possible using a series of gpio's as
chip selects but I don't know the driver-side implications of this.
Re: CF, it calls out 16-bit data and 11-bit address.
Re: nCSx, we have so far stuck to nCS0 for flash (not brought out on the
connector) nCS1,2 for ethernet controllers. CF has its own select protocol.
> Questions on the Connex (92-pin) interface:
> 1) For MMC I only see two signals: MMC chip select 0 and MMC command.
> Where are the other signals MMC Clock and MMC Data? Internal to
> the gumstix module?
> 2) Since NetMMC card obviously has MMC, how does it connect the
> MMC clock and data lines?
> 3) According to the PXA255 manual,I should be able to implement a
> stack of MMC cards using the signals MMCCLK,MMCCMD,MMCDAT.
> Is this possible with gumstix?
> 4) How many data and address lines are required to interface one
> compact flash to the memory controller?
> 5) Its difficult to plan for expansion without knowing what banks
> of memory and which chip selects are already used by gumstix.
> Is this information on the site somewhere? If not can get this
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