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Cork Institute of Technology
Bachelor of Engineering in Electronic Automation &
Robotics (ACCS) - Award
(EELAR_7_Y3)
Summer 2008
Microcomputer Applications
(Time: 2 Hours)
Answer three questions. All questions carry equal marks.
Mr. F. O’Reilly Dr. D. Denieffe Dr. P. O’Sullivan Q1 (a) Compare and contrast microprocessors and micro-controllers. What advantages, disadvantages does each have? [8 marks]
(b) You have the following selection of micro-processors/micro-controllers available to you for a number of projects: (i) Motorola 68000 based micro- controller(MC68332), (ii) Low powered 8051 Micro-controller, (iii) Microchip PIC 16c74. (iv) AMD/Intel Pentium/Athlon Processor For each of the following application choose one and say why you think it is appropriate to that application. DVD Player Control Unit Mobile Phone Embedded Controller. Home/Office Desk Computer [16 marks] (c) The PIC 16c74 arranges its memory into two register banks. What advantages/disadvantages does this have? How do you control which register bank is addressed/selected at any time? [10 marks] [Total: 34 marks]
Q2 (a) Interrupt handling is important for embedded systems. Explain what happens when an interrupt occurs in the PIC and how the interrupt should be handled. Your answer should discuss what memory addresses are used the different types of interrupts available how they can be differentiated [12 marks ]
(b) Derive and explain the following formula based on the Clock Speed and Time, which can be used to calculate the pre-load values for Timer1 of the PIC Micro- controller. How can this be changed to suit Timer2? [10 marks]
Pre-load Value = (^10000) (hex) - Time * FOSC (Using Internal Clock) Prescalar * 4
(c) Calculate the pre-load value for the 16c74 micro-controller to generate a 5.0 kHz square wave using Timer 1 or Timer2, specifying which timer it is for and showing in code how the value would be loaded in. Assume a clock of 4MHz. [12 marks] [Total: 34 marks]
Q3 (a) Describe the capabilities and operation of the Analog to Digital Converter Unit of the Microchip PIC, describing the input signal levels, possible output values and the key registers used both in the configuration and operation. How does one know a conversion has completed? [14 marks]
(b) Write the configuration, interrupt handling and data reading sections of a PIC assembly language program for the 16c74 micro-controller, which continually reads in an analogue voltage from 0 -> 4V on RA0 and outputs it in binary format on PORTB. [20 marks] [Total: 34 marks]
