4-bit SD Card mode

[Neil Bradley]

> I'm not sure I like this at all.  The devices shouldn't be setting up
> the pins for that device.  In some cases, they can't know how to do
> that, and this is one of them.  The device has no way of knowing if
> all 4 wires are connected, or just 1 and the 'spare' lines are used
> for GPIO.

Not doing it will irritate more people (i.e. "I'm not getting full speed 
out of the SD card). While it's a valid concern, I don't think it's 
unrealistic to assume that all 4 DAT lines are hooked up. I've not yet 
encountered a design that A) had SD capabilities, B) was only running 
single bit because of a lack of GPIOs.

-->Neil

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C. Neil Bradley - KE7IXP - The one eyed man in the land of the blind is not
                            king. He's a prisoner.