5V/20K = 0.25mA (250uA).
Shorting the Input to Gnd merely takes away the 1uA the input pin needs for a high.
The internal pullup provides no protection if the pin is set to Output, commanded to High and then shorted to Gnd.
If left shorted, it will blow the output drive transistor sooner or later.
I have an Arduino Due 3.3v.
I plan to configure digital output pins and connect them to inputs I1 to I8 of a UND2981A IC to control frequency inverters.
- a From your previous answer, I understand that external pull resistors are not required.
Can you confirm that for me?
1)b) Nevertheless, external pulling resistances did not improve the free passage between HIGH and LOW ?
- I have code parts to bypass when a switch is closed,
So the best way is to configure the output pin and connect it to the GND and don't forget the 10kohms external pull-up resistor ?
Thank you for your technical advice