ECE251 Intro to Microprocessors Final Exam December 14, 2015, 2 p.m. Name: Solution Instructions: Two sides of single page handwritten study sheet OK. Arithmetic-only calculator OK. No books, other notes, etc. Do NOT communicate with any other student. Work all problems and show ALL intermediate work, NOT just answers. Use engineering notation as appropriate. Return exam AND all handouts. Do NOT write on handouts. 1. (30 points: A=12 points, B=9 points, C=9 points) BASICS A. The following TM4C instructions below are executed in order. What are the results? MOV R0,#0xA00C MOV R1,#0xE2F1 SUBS R2,R0,R1 R2: 0xFFFFBD1B N: 1 C: 0 V: 0 RSBS R3,R0,R1,LSL#16 R3: 0xE2F05FF4 N: 1 C: 1 V: 0 B. The SysTick Timer can generate periodic interrupts. Key SysTick registers include: ST_BASE, ST_CTRL, ST_RELOAD and ST_CURRENT (see p. 5 of exam). If the system clock (not the precision clock) is running at 16.00 MHz, which SysTick register would be set to what value to create an interrupt every 5.00 microseconds? ST_RELOAD Register set to value 79 10. What s the longest interrupt period SysTick can create using this clock? 1.05 sec. C. Show your work on this question. See the memory address decoder system below: 2 Mbyte Assuming Data[7:0], Addr[19:0], and all control signals are correctly connected to 8-bit RAM chips, how much memory is being added, measured in Mbytes? 0x6CC00000 to 0x6CDFFFFF What is the range of memory addresses being added if BIG AND implements the function G2 = A 31 A 30 A 29 A 28 A 27 A 26 A 25 A 24 A 23?
2. (30 points) Analog to Digital Converter A. (26 points) The system below converts a receiver antenna voltage signal directly to a digital signal. The Transducer and Prescaler converts input values linearly into output values. This is NOT the TM4C ATD converter. It is a fast 11-bit converter. 100nsec. If the antenna signal may contain frequencies up to 5 MHz, what is the longest sampling period that may be used? 2.441 mv. What is the resolution of this ATD converter measured at ATD input? 97.65nv. What is the resolution of this ATD converter measured at Antenna Signal? 110 MBit/sec What is the data rate of this ATD converter assuming the Nyquist Rate for the antenna signal above? (Nyquist Rate is 2*5MHz = 10MHz) 0x4F5 24µv. The ATD input is 3.1 v. What digital value is produced? The ATD input is 3.1 v. What antenna signal produced this voltage? -83.8867µv. to -83.7790µv. 0x0A5 is the digital signal output. What range of antenna signals represents this digital value? -83.83785µv. 0x0A5 is the digital signal output. What antenna signal estimate best (smallest maximum error) represents this digital value? B. (4 points)the following questions refer to the TM4C ATD subsystem used in the lab and described in lectures. Succesive Approximation What method of ATD conversion is used? 806µv. What is the resolution of this ATD converter? 12 How many ATD subsystems are on this processor? Yes Is a temperature transducer a part of the ATD subsystem? (+1 right, 0 blank, -1 wrong)
3. (21 points) UART Protocol and Interface A. (15 points) Lucky has asked you to decipher the UART logic signal below. She told you only that it is sent at 9.6 Kbaud and that it shows a Stop bit at the beginning. Specifically, she wants to know the following: 8 bit Is this transmission 7 bit, 8 bit or 9 bit (including possible parity) data? none BYTE What is the data parity (odd, even, or none)? Is each frame ASCII or BYTE information? 0x43 0x53 0xD5 What is the data that has been transmitted? Use or 0x as appropriate. 104.17µsec What is the bit cell time? Label all Start, Stop and Parity bits on the diagram above. Bits 1,2;11,12;21,22;31,32 are alternating Stop and Start bits. No parity bits. B. (6 points) Lucky has found some TM4C UART configuration code but has no idea what it does. Can you help her out a bit here! See p. 5 of exam. ; CPU Bus clock frequency is 50.00 MHz. UART0_BASE EQU 0x4000C000 ; Base Address for UART0 registers LDR R0, =UART0_BASE MOV R1, #81 STR R1, [R0, #0x24] ; Store to IBRD MOV R1, #24 STR R1, [R0, #0x28] ; Store to FBRD 0x4000C024 In instruction STR R1,[R0,0x24] what is (starting) address of memory used? 38.402Kbaud What baud rate is the UART configured for? 0.0064% Extra Credit: If baud rate goal were the nearest exact multiple of 100 baud, e.g. 2400 baud, what percentage error is this configuration?
4. (19 points) SSI Interface: TM4C to Nokia5110 The signals below shows the SSI Clock and TX/Data/MOSI signals being sent from the TM4C to The Nokia5110 display just after its X and Y addresses were set to 0,0. This is one continuous time scale shown across two diagrams to show more detail. What would the upper left-hand corner of the display look like? Please fill in the pixel locations below (12 points): 28µsec If the SSI Clock frequency is 250 KHz, how long is the first (widest) TX/Data/MOSI pulse above? X and Y Types of auto-increment available with Nokia 5110 X Y Auto-increment best used to display alphanumeric characters. Auto-increment best used to display graphics.
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Page 6 ECE251 2012 Final Exam Name: On my honor as a student, I pledge that I have not received or given any unauthorized assistance in this exam. Signature: ASCII TABLE Question #1 work area (if needed):