External SPx peripherals

The SPx peripheral concept is the "highest level" of the SPLat expansion framework. SPx is a proprietary adaption of the industry SPI bus that allows for many addressable peripherals. It is our intention to eventually publish the full SPx specification to permit 3rd-party peripherals.

With SPx the external peripheral (add-on) must have its own processor, simply because the addressing and communications scheme requires intelligence. SPx peripherals can therefore provide high levels of functionality, such as LCD operator consoles, multi-axis motion controllers etc.

SPx peripherals can be visualised (modeled) as containing a number of registers which can be sent commands to execute and data to act upon, and other registers that can be polled (interrogated) for their data. Once sent a command and perhaps some data to work with, the peripheral can go off and "do its thing" without intervention from the SPLat board. This opens up an almost unlimited scope for intelligent peripherals that can perform complex functions with the SPLat only having to provide high level control.

There are over 32,000 possible SPx addresses. Addresses are pre-allocated to specific peripherals. If a setup is likely to need more than one of a particular peripheral, a block of say 16 addresses will be assigned to that peripheral type. The addressing scheme is set out elsewhere, and contains a number of special features. Some addresses are reserved for 3rd party peripherals. Of these, some are "free for all" and others must be registered with us to avoid conflicts.

One SPLat board can control several SPx boards.