> If pad is configured as input, Daisy-chain register is added to select one input from several possible pads.
This also means: if any pad is selected as a desired module port as per IOMUXC, it will only be readable without further initialisation if the pad corresponds to the reset value of the appropriate SELECT_INPUT register! Am I right?
But more generally: in contrast with former MCU-families, modern MCUs can mux each pad individually to a range of port functions. This means that doubling a port feature is possible. No one would ever waste pads for doubling an output port. And doubling an input port is even a recipe for short circuits of internal buffers. No one would ever do this. NXP solves the latter problem. But where is the practical usage bonus? I don't see that.
Let me refer to the reference manual of the i.MX8plus. In section (table) 8.1.1.1. PDM_BIT_STREAM0 can be asssigned to six possible pads. Even all pads at the same time (which would make no sense at all without the "DAISY" feature). When I use the pad that is mentioned first, no further initialisaton of SELECT_INPUT is necessary.
The DAISY feature is explained in section 8.2.2.4. Here, what I wrote at the beginning is part of the description, but it suggests that the input register would only be needed if one is using the "daisy" feature.
The diagram is only in so far informative in that it shows that the input mux is not muxing pads, but muxing at an intermediate location.
Generally, the description lacks further information. Is daisy chain meant ad an internal feature or as facilitation of an external daisy chain, e.g. daisy chained SPI peripheral IC's? But in such a case one will hardly intend to add taps to a daisy chain. Hence, I question if DAISY is an appropriate term here. Simply input mux would fit better. Or am a missing a crucial "feature" point?
