The Freescale Tower is a modular development platform using interchangeable and reusable modules to integrate with Freescale MCU boards as well as a selection of over 50 peripheral modules by various manufacturers. In addition to using premanufactured modules, users can create their own custom boards.
In this app note Freescale describes how to create your own custom module for the Tower system. Details such as integrating with the Tower edge connector pinouts and power sources and limitations are discussed in the context of an example design process of a Custom Relay Module. This information is also important for developers building on the Tower Prototyping Module pictured above.
Freescale has a downloadable executable file containing the app note in PDF along with the files associated with the Relay Module example, as well as a Tower Module Template for use with Eagle.