Pinebook SDIO gpio control using SD card slot blog post
#7


My first clue that the bindings may not be entirely correct is that inputs with active_low=1 don't work.  By default when I setup an input (used PF4 and PF5) then active_low=0 ;  which means the default state of the pin is zero and it becomes active 'high';  this works !  Set the pin to 3v3 and its value becomes 1.

On the other hand, if I set active_low=1 then the input pin does not work;  its value remains default '1' regardless of grounding the pin ( setting it to low zero ).  So, I suspect I need to revisit 'pull' and 'drive'  and fix whatever I don't understand there.

Note:   ofc an external pullup of 56K ohms works fine to invert the behavior of the input 

Note:   regardless, we have both input and output working with gpio block @sdc0 ( PF0 - PF5 )  gpio160 - gpio165.

Note:   need to make the dts generic ;  and get the C and Python routines working.


marcushh777    Cool

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RE: Pinebook SDIO gpio control using SD card slot blog post - by MarkHaysHarris777 - 07-23-2017, 06:27 AM

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