We are currently developing a new industrial process controller for applications with very low cycle times (<50us). The embedded software that runs on this controller shall be validated automatically in the future. The controller is then seen as a black box that can only be accessed through its I/O and API. From a software testing perspective (CI/CD), I would like to give our hardware developers some input so that they can design the controller so that the embedded software running on it becomes as "testable" as possible. Which interfaces, functions, etc. should a controller offer in terms of hardware and software in order to achieve this goal? Are there any general design specifications in this regard?