It was not so long after the first edition that the need for a second edition began to be felt. Embedded technology was moving fast, and Microchip had come up with a whole set of new 16- and 32-bit microcontrollers, just as the first edition was being finalised. Big developments were meanwhile taking place in the 8-bit field, for example with the increasing application of nanoWatt technology and more advanced peripherals.

This edition has the same starting point as the first edition, but aims to include some recent developments. The awkward question arises: what microcontrollers do we use as examples – the newest or the easiest to grasp? I took the choice to stick with the old favourite, the 16F84A, as the first example device. This makes such a good and simple starting point that it is hard to beat, even with a more recent product. From here the path moves to the larger but still well-established 16 Series microcontroller, the 16F873A. This launches us into larger microcontrollers and the many interesting issues surrounding their peripherals. So far, things are similar to the first edition, though with more detail on introductory programming. The book then takes in advances seen in two rather recent 16 Series microcontrollers, the 16F88 and 16F883. These are used to introduce, among other things, the important topics of low-power technology and more advanced oscillator design. The chapters using the C programming language are then based on the 18F2420, replacing the 18F242 of the earlier edition. The final chapter is new, giving an introduction to the Microchip 16- and 32-bit microcontrollers.

Much of the book continues to use the Derbot Autonomous Guided Vehicle as its main design example. As before, the book can be read with complete benefit whether or not a build is completed. In the past few years at Derby University we have seen several generations of the Derbot spring to life, and kits have been sent to different parts of the world. A host of variations and refinements have thus appeared, many reported on the book's companion web site: www.elsevierdirect.com/companions/9781856177504.

To conclude, I simply repeat the end of the introduction to the first edition: I hope that you enjoy working through this book. In particular I hope you go on to enjoy the challenge and pleasure of designing and building embedded systems.

Tim Wilmshurst

University of Derby