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Number Systems To use a microprocessor or microcontroller efficiently requires a working knowledge of binary, decimal, and hexadecimal numbering systems. This section provides background information about these numbering systems for readers who are unfamiliar with them or do not know how to convert from one number system to another. Number systems are classified according to […]
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Microcontroller Architectures Two types of architectures are conventional in microcontrollers (see Figure 1.4). Von Neumann architecture, used by a large percentage of microcontrollers, places all memory space on the same bus; instruction and data also use the same bus. In Harvard architecture (used by PIC microcontrollers), code and data are on separate buses, which allows […]
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Microcontroller Features Microcontrollers from different manufacturers have different architectures and different capabilities. Some may suit a particular application while others may be totally unsuitable for the same application. The hardware features common to most microcontrollers are described in this section. Supply Voltage Most microcontrollers operate with the standard logic voltage of þ5V. Some microcontrollers can […]
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Microcontroller Systems A microcontroller is a single-chip computer. Micro suggests that the device is small, and controller suggests that it is used in control applications. Another term for microcontroller is embedded controller, since most of the microcontrollers are built into (or embedded in) the devices they control. A microprocessor differs from a microcontroller in a […]
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Introduction The term microcomputer is used to describe a system that includes at minimum a microprocessor, program memory, data memory, and an input-output (I/O) device. Some microcomputer systems include additional components such as timers, counters, and analog-to-digital converters. Thus, a microcomputer system can be anything from a large computer having hard disks, floppy disks, and […]
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DIGITAL CONTROLLERS In general, we can make use of the block diagram shown in Figure 9.3 when designing a digital controller. In this figure, R(z) is the reference input, E (z) is the error signal, U (z) is the output of the controller, and Y (z) is the output of the system. HG(z) represents the […]
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DESIGNING A CONTROLLER The circuit diagram of the closed-loop system is shown in Figure 11.10. The loop is closed by connecting the output of the level sensor to the analog input AN0 of the microcontroller. Notice that the output of the microcontroller was set to 200, which corresponds to 200× 5000/256 = 3906 mV, and […]
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IDENTIFICATION OF THE SYSTEM The system was identified by carrying out a simple step response test. Figure 11.6 shows the hardware set-up for the step response test. The port B output of the microcontroller is connected to data inputs of the D/A converter, and the converter is controlled from pin RC0 of the microcontroller. The […]
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SYSTEM MODEL The system is basically a first-order system. The tank acts as a fluid capacitor where fluid enters and leaves the tank. According to mass balance, where Qin is the flow rate of water into the tank, Q the rate of water storage in the tank, and Qout the flow rate of water out […]
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MICROCONTROLLER IMPLEMENTATIONS The final stage of a digital control system design is the implementation of the controller algorithm (set of difference equations) on a digital computer. In this section, we shall explore the implementation of digital controller algorithms on PIC microcontrollers. The PIC 16F877 microcontroller will be used in the examples since this microcontroller has […]
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