A note about PICO's pull-up resistors

A project log for A 'smart' controller for a powered chair or bed

Automates the powered recliner or bed. Ideal for the mobility-challenged.

stephen-craverStephen Craver 06/02/2023 at 21:130 Comments

The Pin.PULL_UP settings are now Pin.PULL_DOWN, and not really needed.


Because by default, the controller (button) contacts are normally-closed to ground, thus eliminating the need of a PULL_DOWN resistor. The normally-open side is +5VDC.

Yeah but...

 There is always a caveat: The above reigns true IF a controller is plugged in. If not, the inputs will "float" in an incalculable state. That would be bad, am I right? (The answer is yes)

The bottom line: 

PICO's internal Pin.PULL_DOWN setting will work just fine for unconnected controllers.