SMI Interface and GPIO pin usability

[martinpetrovaj]

Hi, I'd like to clear up whether GPIO pins on rpi can be used normally alongside the CaribouLite SDR HAT, or if their use is limited (and how / what are the limitations or needed adjustments)

After a superficial Google search I found this diagram (source), showing that all GPIO pins except for GPIO 26 & GPIO 27 are utilized by the SMI (Secondary Memory Interface).

Could someone familiar with either the interface or CaribouLite shed more light on the topic?

While I appreciate the engineering skill, ingenuity and craftsmanship that made CaribouLite's impressive performance possible, I'm interested in the platform mainly for its wide frequency coverage, "two channels in one board", and well-documented software; but would love to retain the possibility to control other hardware from my pi via GPIO as well. Just a personal preference / use case, certainly not intended as a jab or anything of that sort.