Final Examination Solutions Fall 2007

PwnHero Final Examination COE538-Microprocessor Systems December 6, 2007 Name: _______________________________________ Student #: ______________ Section #: ______ Time limit: 3 hours Examiners: V. Geurkov, A. Ye Notes: a) Closed book. b) No questions during exam period. State any assumptions. c) Answer neatly all questions in the space provided. Unclear answers will not be accepted. d) For each question, show the process that is used to derive the answer. e) Circle your professor’s name and hand in these sheets. 1. Short Answer Questions: [1 mark each] a) How many bits of data are stored in each memory location of the 68HC11 microcontroller? 8 bits. b) How many different memory locations can the 68HC11 microcontroller address? 216 = 65536. c) What is the basic difference between the RTI and RTS instructions? RTS returns the return address from the stack. RTI returns the return address and all the registers except SP. d) Can the user change the 68HC11 operation mode after the RESET signal goes high? Only within 64 clock cycles. e) What are the advantages of using interrupts to handle data input and output? Immediate response to the data input update. Immediate change of data output as an event occurs in the system. f) What is isolated I/O? What is memory-mapped I/O? In the isolated I/O, I/O devices have their own address space, which is separate from the main memory address space. In isolated I/O method, input and output operations have dedicated instructions. g) How does the SCI system of the 68HC11 processor determine the logic level of data bits? The level is sampled three times at the middle of the time slot allocated for the bit (7th, 8th and 9th pulses; the baud rate is internally divided by 16). The level is determined by majority. h) What is multidrop serial communication? It is communication between more than two stations, one of which is a primary device (master). The primary device controls all communications. Each station has its own unique address. PwnHero.com