Embedded Systems: An Integrated Approach by Pearson

42 EMBEDDED SYSTEMS

using an MCU. If an operating system is being used for the system, its ‘footprint’ should

be small.

High Speed As a general case, we would like systems to respond fast. For an embedded

MCU, fast response implies high clock frequency—but the higher the clock frequency,

higher will be the power dissipation—so the trick is not to choose an unnecessarily

high clock frequency unless the application needs it. For simple applications, if PIC

and 8051 MCUs are used, we fi nd that frequencies in the range of 12–20 MHz are

common.  is is not a high frequency compared to clock frequencies of general purpose

processors (2 to 3 GHz). But higher end systems are likely to use MCUs (like ARM)

with much higher clock frequencies for faster ...