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Ebook Embedded hardware: Part 2

(BQ) Part 2 book "Embedded hardware" has contents: Analysis in embedded systems, choosing a microcontroller and other design decisions, the essence of microcontroller networking, interfacing to sensors and actuators, other useful hardware design tips and techniques. | CHAPTER 6 Timing Analysis in Embedded Systems CHAPTER 6 Ken Arnold 6.1 Introduction Just as in comedy, timing is essential to the success of a microcomputer design. Often it is quite possible to get one system functioning by simply interconnecting the various components. But it is significantly more difficult to be able to guarantee that many systems will work under the entire range of possible conditions that they may be exposed to. There are many designs in production right now that have a number of unidentified failures due to the lack of a worst-case analysis of the design. When timing or loading problems show up in a design, they usually appear as intermittent failures or as sensitivity to power supply fluctuations, temperature changes, and so on. A worst-case design takes into account all available information regarding the components to be used with respect to variations in performance. Even when all parameters are at their most adverse values, the worst-case design can still be proved to meet the specifications. These variants may be due to changing manufacturing conditions, temperature, voltage, and other variables. Without performing a detailed analysis, there is no way of knowing if the design will work reliably under all operating conditions. It is much better to design reliability and simplicity of manufacturing into a product using worst-case design rules than to attempt to correct a problem after the design has been implemented. With the emphasis that must be given to the quality of the final product, a designer is obligated to perform a detailed examination of the timing in a system. As is the case in most quality improvements, these efforts result in direct cost and saving time. This is clearly one of the places where the designer can have the greatest impact on overall product quality. 6.2 Timing Diagram Notation Conventions Timing notation is illustrated in Figure 6.1. The timing notation used in manufacturers’ data sheets may vary from this .