Electronics Explorer Static I/O, unused LEDs light

[Rick314]

Electronics Explorer Static I/O DIO pins configured as LEDs that are unused/unconnected will light when an adjacent driven LED lights.

Details: Board power ON, nothing in the breadboard area, Supplies "Fixed Supply - Vcc" = 5V and "Master Enable" On, Static I/O DIO 31-8 = LEDs, DIO 7-0 = Bit I/O, Switch, Push/Pull.  Connecting a wire from DIO 8 to Vcc lights both LED 8 and 9 solidly (DIO 9 has nothing connected to it.)  Similarly, connecting Vcc to DIO 9 only results in both LED 9 and 8 on.  The same is true for LED pairs 10 and 11, 12 and 13, 14 and 15...  The current workaround is to configure the LEDs adjacent to used ones as non-LED (e.g. a Button) to keep them out of consideration.  But shouldn't unused LEDs always be off?  Why is it only an issue with adjacent pairs?

[attila]

Hi @Rick314

 

[Rick314]

Thank you attila, that makes sense.  But then it seems that "LED" is an unwise default value of all Static I/O pins, being equivalent to "32 antennas sensing nearby DIO pins or other stray signals".  Defaulting to some driven choice (an output with a default 0 or 1) seems like a better choice, so it takes intentional user action to turn them into antennas.  Do you agree?

[attila]

Hi @Rick314

The DigitalIO pins can be used as input (high impedance) or output (driving 0/3.3V).
The high impedance mode is considered to be safest option and it is used as default.

[Rick314]

> The high impedance mode is considered to be safest option and it is used as default.

Thank you for your reply attila, but "is considered" by who and "to be the safest option" why?

I described why this is a problem -- In my college Digital Logic class using 9 Electronics Explorer boards for the first time, over half the students experienced unexpected Static I/O LED outputs turning on for no apparent reason.  This is a problem.  Explaining what was happening had nothing to do with the lesson.  There isn't really any "safety" problem with the default configuration being outputs, is there?  (I am a software engineer with decades of test equipment user interface design experience.)  It seems the highest RIO fix for the problem is to make the default configuration of the Static I/O DIO pins be as outputs.

[attila]

Hi @Rick314

Thank you for your sharing your opinion.
As solution for the StaticIO interface make the unused IOs output by selecting slider, button or switch. You could also provide the students project or workspace with this configuration.