Embedded Systems Laboratory

PATTERNS FOR TIME -TRIGGERED EMBEDDED SYSTEMS:
Building reliable applications with the 8051 family of microcontrollers

This WWW page provides information supporting the book " Patterns for Time-Triggered Embedded Systems " ( PTTES ).

This substantial (1000-page) book, and associated CD, together describe the first comprehensive set of ‘design patterns’ to support the development of embedded systems based on the 8051 family of microcontrollers. In total, PTTES contains details of more than 70 useful software patterns, complete with guidelines to help you apply these techniques in your own projects: full source code for all of the patterns is included on the associated CD.

• The focus is on the rapid development of software for time-triggered, embedded systems, using software patterns. The meaning of ‘time-triggered’ is explained in Chapter 1; software patterns are introduced in Chapter 2.

• The systems are all based on microcontrollers, from the widely-used 8051 family. This vast family of devices is manufactured by a number of companies, including Philips, Infineon, Atmel, Dallas, Texas Instruments and Intel. The range of different 8051 microcontrollers available is reviewed in Chapter 3.

• Time-triggered techniques are the usual choice in safety-related applications, where reliability is a crucial design requirement. However, the need for reliability is not restricted to systems such as drive-by-wire passenger cars, aerospace systems or monitoring systems for industrial robots: even at the lowest level, an alarm clock that fails to sound on time, or a video recorder that operates intermittently may not have safety implications but, equally, will not have high sales figures. The patterns presented here allow time-triggered techniques to be simply and cost-effectively applied in virtually any embedded project.

• The applications discussed in detail must carry out tasks or respond to events over time intervals measured in milliseconds. This level of response can be economically and reliably achieved with an 8-bit microcontroller using the approaches discussed in this book, and is appropriate for many applications, up to and including aircraft flight control systems.

• The software is implemented entirely in ‘C’. All of the source code in the book appears on the enclosed CD.

• The time-triggered systems in this book are created using schedulers. Briefly, a scheduler is a very simple ‘operating system’ suitable for use in embedded applications (see Chapter 13 for a detailed introduction to this topic).

• A range of complete scheduler architectures for applications involving a single microcontroller is described and illustrated (Chapter 14 to Chapter 17). Complete source code for a large number of different schedulers is included on the CD.

• Like an increasing number of applications, many of the systems presented here involve the use of more than one microcontroller: a range of shared-clock schedulers architectures that can support this type of application is described (Chapter 25 to Chapter 29). Many of these systems make use of popular serial standards, including the CAN bus and RS-485.

• A selection of more specialised scheduler architectures are also presented (in Part H). This includes a ‘stable’ scheduler that can provide very precise timing over long periods, a scheduler optimised to run a single task, and general-purpose schedulers designed for low-power and / or low-memory applications. See Chapter 36 to Chapter 38.

• All embedded systems involve some hardware design, and suitable hardware foundations are presented. These include designs for oscillator and reset circuits, and techniques for connecting external ROM and RAM memory (see Chapter 4, Chapter 5 and Chapter 6). These also include interface circuits suitable for use with low- and high-voltage DC and AC loads (see Chapter 7 and Chapter 8).

• Suitable software foundations are also presented, including a simple architecture for embedded applications (Chapter 9), techniques for controlling port pins (Chapter 10), techniques for generating delays (Chapter 11), and techniques for using watchdog timers (Chapter 12).

• A key part of the user interface of some embedded applications is an ‘RS-232’ link to a desktop or notebook PC, while many other embedded systems have a user interface created using an LCD or LED display along with a small collection of switches and / or a keypad. Techniques for working with these different interface components are presented in Chapter 18 to Chapter 22.

• Many modern different peripheral devices (LCDs, LED displays, EEPROMs, A-D and D-A devices and so on) now have a serial interface, with the result that these devices can be connected to a microcontroller without consuming large numbers of port pins. Complete software libraries for the two main serial communication protocols (I ² C and SPI) are presented in Chapter 23 and Chapter 24.

• Techniques suitable for use in condition monitoring and control applications are presented in Part G. This includes discussion of various control algorithms, including ‘PID control’, and detailed code libraries are provided (Chapter 30 to Chapter 35).

Anything missing? Please e-mail the author: M.Pont _at_ le.ac.uk

Last updated: 29 March 2008 16:34
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