When using ICs that use enable pins, what is the best practice for driving them in a microcontroller system (particularly when there's no especially pressing need to disable the device at any time)?
For example, I'm using a chain of parallel-to-serial shift registers to aggregate a large number of physical device inputs into a single serial bitstream to my uC, and these registers only operate when a clk_en clock enable pin is driven low.
The inputs will be polled for the lifetime of the uC, so at no point do I NEED to explicitly disable the clk_en signal.
Is it considered bad practice to have this pin permanently pulled low (i.e. with a pull-down resistor)?
Best Answer
I don't think that would be bad practice, just choose an adequate pull-down resistor.
In order to make the design flexible though, you could also add a zero ohm jumper to that enable pin (a do-not-stuff component) along with the pull down resistor, just in case you need to do some debugging in the future, never know. That zero ohm jumper could connect to one of the GPIOs, Vcc, or some header pin you may want to add for debugging or whatnot.