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CS/ECEn 124, W2012 Homework #6 MSP430 Assembler (Ch 7) Stacks (Ch 8) Name Questions: Answers: Section Score / 46 (18 points) What native MSP430 instruction is replaced by the assembler for each of the following emulated instruction? a b c d e f g h i j k l m n o p q r ADC.W dst DEC dst DECD dst INC dst INCD dst INV.B dst RLA.W dst RLC.B dst CLR dst CLRC POP dst SETZ TST.B dst BR dst DINT EINT NOP RET (2 points) What MSP430 instruction could be used for a word, cycle NOP? (6 points) The following operations are performed on a stack: PUSH A, PUSH B, POP, PUSH C, PUSH D, POP, PUSH E, PUSH F, POP, POP, POP, PUSH F a What does the stack contain after the last PUSH F? b At which point does the stack contain the most elements? c Without removing any elements left on the stack from the previous operations, what does the stack contain after the following additional operations? PUSH G, PUSH H, PUSH I, PUSH J, POP, PUSH K, POP, POP, POP, PUSH L, POP, POP, PUSH M BYU, ECEn/CS 124, W2012 Homework #6 Page 1/2 (10 points) How many cycles are used by each of the following instructions: a mov.w r5,r6 b mov.b r5,r6 c add.b @r5,r6 d add.b 10(r5),r6 e sub.w 10(r5),20(r6) f mov.w #1,r5 g mov.w #100,r5 h jmp label i jne label (4 points) Power consumption is directly related to the number of instruction cycles used by a system Show and explain the difference in power consumption between a adding a Program A (that uses a billion cycles on startup and then another billion cycles once per subsequent year) to a system, and b adding a single extra instruction cycle to an existing Program B (which executes 1024 times per second) Explain your answer in terms of cycles per year (6 points) A watch crystal has a strange looking frequency of 32,768 Hz (cycles/second) This frequency is convenient for real-time clocks because it is the largest positive value that can be used with a decrementing 16-bit counter When the timer counts down to zero, one second has expired a John Harrison’s H4 chronometer (clock) accumulated an error of 5.1 seconds over 81 days when it was first taken to sea for testing in 1761 A typical watch crystal has an error of 20 parts per million (ppm) How many times more accurate was Harrison’s clock than a watch crystal controlled clock? b How accurate of a crystal is needed for a realtime clock (in parts per million error) in order to be at least as accurate as Harrison’s clock? (Hint: Read “Clock accuracy in ppm” found in the Readings section of References.) BYU, ECEn/CS 124, W2012 Homework #6 Page 2/2