Some (real) example use cases:
* Example 1: I have some SPI traffic that I want the HLA to annotate it with different data depending on the state of some other GPIO pins.
* Example 2: I have some serial traffic that contains a battery voltage reading, and I want the HLA to compare that reading with some analog data on another channel.
* Example 3: I want to combine the aforementioned serial and SPI traffic to see e.g. the time between some event on the SPI bus and an associated event on the serial bus.
I have an application that fits example 1; a wireless module that has a pin that selects if the serial data into and out of the module is over the air data or commands for the chip.