EE345M Final Exam B Fall 2004 Page 1 of 8 Jonathan W. Valvano First Name: _______________ Last Name:____________________ December 12, 2004, 7-10pm This is an open book, open notes exam. You must put answers on these papers; please don’t turn in any extra sheets. The first three questions involve the development of three different solutions to the same problem. The common objective of three systems is to measure resistance with a range of 1000 to 2000 ohms with as good a resolution as possible. (10) Question 1. The first solution technique involves a resistance bridge and instrumentation amplifier. The ADC is 10-bits and has a range of 0 to +5V. +2.50VRVout1kΩRef031kΩ1kΩVin9S12C32instrumentation amp Part a) What is range of voltages appearing on Vin? Part b) What gain is needed on the instrumentation amp? Part c) What will be resistance measurement resolution?EE345M Final Exam B Fall 2004 Page 2 of 8 (10) Question 2. The second solution technique involves a constant current source and linear amplifier. The ADC is again 10-bits and has a range of 0 to +5V. Vout9S12C32+2.50VRef031kΩVinRop amp your circuit Part a) This is a constant current source. How much current flows across the resistor R? Part b) What is the linear equation required to map the full scale range of R into the full scale range of the ADC? Part c) What will be resistance measurement resolution?EE345M Final Exam B Fall 2004 Page 3 of 8 (10) Question 3. The third solution technique involves an astable multivibrator and period measurement. If the C is the capacitance in µF and the resistance in Ω, then the period (in µs) of a TLC555 timer is 0.693•C•(R+2RB). In this circuit RB is a 1000Ω fixed resistor. 8TLC5551000Ω+51GndVddOut3RBC56 27ThresDisch TrigResetCont0.1µF0.1µF4+5PT768121% metal film1% mylar Part a) Assume the TCNT is running at 4MHz, therefore its period is 250ns. What is the largest period that can be measured with a single channel of input capture? Part b) Choose a value for the capacitor, C, so that the period is that maximum value when the input resistance is 2000 Ω. Part c) What will be resistance measurement resolution?EE345M Final Exam B Fall 2004 Page 4 of 8 (5) Question 4. The 6812 is running in expanded mode with 4 megabytes of extended program page ROM. Fill in the two boxes in the following software that reads physical location $35678. PPAGE = ; data = *((char *)( )); (10) Question 5. The motor voltage is +12 V and its current is 0.25 A. Show the hardware interface circuit that allows you to rotate the motor in both directions. PT0 is a pulse-width modulated wave to specify the amount of power, and PT1 controls the direction. PT1PT06812 (10) Question 6. A 74C74 CMOS D flip-flop clocks its Data input on the rising edge of its Clk. For this chip, the setup time is 50 ns, and the hold time is 20 ns. A system using the 74C74 provides valid information to the Data input during this interval: Data = ([80,100], [200,220]) and the rising edge of the Clk occurs at ?Clk = [170,190] Will the data be properly stored? Use timing analysis to justify your answer.EE345M Final Exam B Fall 2004 Page 5 of 8 (10) Question 7. A fuzzy logic controller needs to execute the following fuzzification step. inputmembershipsetcrisp input0 80 165 197 240 2550$FF Part a) What four constants should be stored in the ROM-based structure to allow the controller to execute this fuzzification with the mem instruction? Hint: your answer will be approximate, so round to the closest integer. Your answer will be similar in format to Program 13.19 from the book. Part b) There are three input membership sets: Happy, Healthy, and Wise. There is one output membership set, Good. Consider the Fuzzy logic equation Good = Happy*(Healthy+Wise) Assume Happy =100, Healthy =200, and Wise =50. Calculate the value of Good for this case. Part c) Show the ROM-based data structure to define this Fuzzy logic equation so it could be executed using the rev instruction. Your answer will be similar in format to Program 13.21 from the book. You may assume the following RAM-based global variables org $3800 ; membership variables HAPPY: ds 1 HEALTHY: ds 1 WISE: ds 1 GOOD: ds 1 ; input membership variables relative offsets happy: equ 0 healthy: equ 1 wise: equ 2 good: equ 3EE345M Final Exam B Fall 2004 Page 6 of 8 (10) Question 8. Design an analog circuit that implements Vout = 4V2 + 2V1 + V0 using one op amp. Show your work.EE345M Final Exam B Fall 2004 Page 7 of 8 (25) Question 9. Path expression is a formal mechanism to specify the correct calling order in a group of related functions. Consider a SCI device driver with 4 functions, the prototypes are void SCI_Init(void); // Initialize Serial port char SCI_InChar(void); // Wait for new serial port input void SCI_OutChar(char data); // Output 8-bit to serial port void SCI_Close(void); // Shut down serial port It is obvious that you should not attempt to input/output until the SCI is initialized. In this problem, we will go further and actually prevent the user from executing SCI_InChar and SCI_OutChar before executing SCI_Init. A directed graph is a general method to specify the valid calling sequences. An arrow represents a valid calling sequence within the path expression. The system “state” is determined by the function it called last. For this example, we begin in the closed state, because the SCI is initially disabled. The tail of an arrow touches the function we called last, and the head of an arrow points to a function that we are allowed to call next. SCI_InitSCI_OutCharSCI_InCharSCI_Closedbeijfacgh In this method, a calling sequence is valid if there is sequence of arrows to define it. E.g., Init InChar InChar OutChar Close d b e i j Init OutChar OutChar OutChar OutChar d c g g g Init Close Init InChar Close d a d b h On the other hand, the following calling sequences are illegal because each has no representative sequence of arrows Init InChar Init OutChar Close can’t initialize twice Close can’t close because already disabled OutChar OutChar OutChar can’t output without initialization A fast, but memory