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 50V Ref03 1k 1k Vout 9S12C32 V in R 1k 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 instrumentation amp 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 R 1k 2 50V Ref03 op amp V in your circuit Vout 9S12C32 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 F and the resistance in then the period in s of a TLC555 timer is 0 693 C R 2RB In this circuit RB is a 1000 fixed resistor 1000 1 metal film 1 mylar 5 6812 PT7 0 1 F R B 6 7 2 Disch Thres Trig 4 Reset 3 Out TLC555 Vdd 8 5 Cont Gnd 1 C 5 0 1 F 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 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 6812 PT1 PT0 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 FF input membership set crisp input 0 0 80 165 197 240 255 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 3 EE345M Final Exam B Fall 2004 10 Question 8 Design an analog circuit that implements Vout 4V2 2V1 V0 using one op amp Show your work Page 6 of 8 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 char void void SCI Init void SCI InChar void SCI OutChar char data SCI Close void Initialize Serial port Wait for new serial port input Output 8 bit to serial port 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 e a SCI Init b SCI InChar h c f SCI OutChar i j SCI Close d g 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 inefficient method to represent a directed graph uses a square matrix Since there are four functions the matrix will be 4 by 4 The row number 0 1 2 3 will specify the current state the function called last and the column number 0 1 2 3 will specify the function that might be called next The values in the matrix are true …