Download Interrupt handling - Computer Systems - Exam and more Exams Computer Science in PDF only on Docsity!
Cork Institute of Technology
Bachelor of Engineering (Honours) in Electronic Engineering -
Stage 3
(NFQ - Level 8)
Spring 2007
Computer Systems
(Time: 3 Hours)
Answer any four questions [each 25 marks] Maximum available marks is 100. Use appropriate comments and indentation in program code. PIC and 68000 instruction sets attached.
Examiners: Mr. P. Cogan Prof. G. Hurley Dr. S. Foley
Q1. (a)^ A RISC processor architecture forms the core of the PIC microcontroller.
Briefly discuss the advantages and disadvantages of this kind of microprocessor architecture for embedded systems [6 marks]
(b) Compare and contrast the operation of the PIC microcontroller’s Synchronous Serial Port (SSP) module with its Universal Synchronous Asynchronous Receiver Transmitter (USART) module. Give some typical examples of how each module might be used. [6 marks]
(c) Write an assembly language program for a PIC 16F74 with a crystal frequency of 4MHz that performs the following. Any value received by the USART should be written to PORT D. Any change in the levels on the pins of PORT B should result in the new state of PORT B being transmitted using the USART. Configure the USART for operation at 9600 baud, no parity and with one stop bit. State any assumptions that you make. [13 marks]
continued overleaf ….
Q2. (a) Briefly describe interrupt handling on the PIC16C74. [6 marks]
(b) Demonstrate how the PIC 16F74 ADC can be used to sample an analogue voltage using an interrupt driven assembly language example. [8 marks]
(c) Design a PIC based controller that implements a parking assistance system. The system must sound an alarm if the vehicle in which it is installed is less than 10cm from an obstacle. At least four ultrasonic sensors are required, two for the front and the other two for the rear of the vehicle. An alarm mute button should also be included in the design. The ultrasonic sensor modules, which the system must use, produce a 5V peak square wave output. The frequency of this waveform is proportional to the distance of the sensor from an object and varies from 100Hz if the object is more than 3m away to 2kHz when the object is 10cm away. LEDs should indicate which sensor is causing the alarm to sound. Draw the circuit diagram for your controller on the attached sheet (showing the pinout for the PIC) and give the algorithm for how your software will operate. State any assumptions that you made about the requirements of the design. [11 marks]
Q3. (a) Using the following statistics, describe and justify the micro-processor features which are implemented in RISC processors to improve performance over CISC processors. [8 marks]
Operand Types Frequency Operation Types/Frequency in C language Integer Constant 20% Assignment 38 %
If 43%
Scalar Variable 55% Loop 3% Goto 3% Array/Structure 25% Call 12 %
Othe r
1%
Typical depth of function calls = 8. 6 or less scalar variables per procedure > 92% of time 6 or less arguments per procedure call > 98% of time
(b) Discuss the key elements required to implement a microprocessor development system. Describe for a processor of your choice, how a development system allowing in-circuit debugging could be achieved. [8 marks]
(c) Caching schemes employ the principle of locality to keep cost down and performance up. Discuss this using appropriate examples. [9 marks]
continued overleaf ….
Q6. (a) Describe with the help of a diagram the five layers of the Internet reference
model (TCP/IP model). Using this model, explain how data from an application program is transformed as it is passed through the five layers mentioned above and what happens when the data reaches its destination. [8 marks]
(b) Write a note on routing in computer networks that briefly explains; (i) What is meant by routing? (ii) What is the difference between virtual circuit routing and datagram routing? (iii) What layer of the Internet reference model does a router operate at? Explain why this is the case. [9 marks]
(c) Describe the ALOHA system of multiple access control. How does slotted ALOHA improve data throughput? [8 marks]
ooooOOOOoooo
