IBM discusses some of the advantages of migrating from x86 to PowerPC and how it can be accomplished on a lot less money than you might think. For the most part, I can see why the Power PC would be of some advantage. Still, one has to wonder just how much time difference it really provides for by using one vs the other.

An attractive, speedy route to developing complex, initially loosely specified applications that have a mix of real-time and non-real-time components is to take a fairly powerful x86-based PC-compatible single-board computer running Linux™, and use a slenderized custom software bundle on that machine to control a bevy of assorted small microcontrollers configured to handle the hard real-time tasks in the system.

You save development time principally from the fact that you can buy off-the-shelf hardware for most of the functions to be carried out on the PC; you can use an off-the-shelf operating system, and you can use ready-rolled device drivers that have already been debugged for you, for the most part.

You can also carry out your control software development using the actual target PC platform (possibly with minor extensions: more RAM, a hard disk, and so on) as the compiler host. Running the application, build environment, and native debugger directly on the target system can significantly shorten your development cycle. Furthermore, modularizing the real-time components of your application (stepper motor control, analog data acquisition, and the like) into separate microcontrollers helps you to develop those modules without having to worry about real-time interaction issues between multiple tasks running on a single processor.

Then, once your embedded application is tested and debugged — and, more importantly, once the entire device’s capabilities and system requirements are better defined through experiment and field-testing — it is possible to take your well written Linux application and port it into a more deeply embedded environment.

The easiest path here is to use a platform running a Linux variant on some RISC microprocessor or SoC. If desirable, some functionality can simultaneously be shifted out of those external satellite microcontrollers into SoC hardware or firmware running in that 32-bit micro.

I recently demonstrated several practical examples of the above techniques in my second book, A Cookbook for Open-Source Robotics and Process Control (see Resources). That work focused on the electronics and firmware design of an autonomous underwater vehicle (a robot submarine). This series of articles essentially carries on from that work to demonstrate the second stage of refinement: porting the x86-based application to a PowerPC® environment, and redeveloping the hardware interfaces to fit the PowerPC (PPC) system.