There are a lot of cheap MicroSD port extender flex ribbons from China. These things extend the MicroSD port quite a lot. I thought it would be cool to adapt these to power an Arduino from a phones MicroSD port. This would solve my problem of having to deal with USB OTG power and would be a nicer solution as the USB port could still be used.
My question; does the MicroSD port need signalling before VDD is powered?
And additionally, would it be possible to communicate a signal over the data lines with Arduino, or would that be really hard? A very minimalistic signal would already be nice.
Lastly, what can I expect to be the amperage to be supplied? Looking at a datasheet from a typical MicroSD card I see it requires 100ma to operate, so I figure at least that.