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Ability to use Pi's internal pull up/down resistors for digital inputs #19
Interesting- what's your use case for this?
I was originally concerned about the voltage divider the 50K pull-down would create with the 20K current-limiting series resistor but - if my maths serves me correctly - it only lifts the minimum required voltage for a stable "HIGH" to around 2.5v.
@Gadgetoid , my original use case is a doorbell.
I used the available 5volt of the Automation HAT directly for my doorbell switch connected to the digital input of the Automation HAT without any pull-down resistor. Because of the floating-ground issue, the readings on the input where not reliable but after activating the internal pull-down resistor of the Pi, the input is now reliable.
Also I use it now for a second use-case which is a 12volt motion detector which gets is 12volt from an external source and pulls a second 12volt line down when it detects motion. Here I also needed to activate the internal pull-up resistor on the analog input to get a reliable reading (same floating-ground issue I assume :) ).