Pinebook SDIO gpio control using SD card slot blog post

[tllim]

This is my first experiment with bringing some of the A64 gpio mux lines to the outside via the SD card slot;  SDIO.  These are data lines D0-D3, CMD, CLK, VDD, & VSS.  The lines are gpio160 - gpio166;  PF0 - PF6.

The pic above is the 48cm ribbon cable that extends the SD micro slot to a full size card adapter;  this ribbon is useful in itself;  but I plan to modify it for pin access on a solderable bread-board.

 

These two shots are the modified ribbon cable;  this was actually easier than I expected.  The cable will extend under the notebook.

 

The two shots above show the finished cable running;  I have the green and red LED(s) initially connected to CMD and CLK.  These are pulsing at regular 3/4 second intervals (or so).  The gpio(s) are not useful in this state;  next I need to hack the dts and make sure that the pin function register has '0' s. 

Stay tuned.

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