University of Florida EEL 4744 Spring 2011 Dr. Eric M. Schwartz Department of Electrical & Computer Engineering 31 March Apr-11 1:29 PM

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1 University of Florida EE 4744 Spring 2011 Dr. Eric M. Schwartz Page 1/15 Exam 2 Go Gators! Instructions: Turn off cell phones beepers and other noise making devices. Show all work on the front of the test papers. If you need more room make a clearly indicated note on the front of the page "MORE ON BACK" and use the back. The back of the page will not be graded without an indication on the front. You may use any of your TI documents with limited added material; highlighting and tagging is permissible. You may not use any notes (mine or yours) examples homework labs books calculators computer electronic devices etc. Put your name at the top of each test page and be sure your exam consists of 15 distinct pages. The space provided does not necessarily represent the amount of writing necessary. You must pledge and sign this page in order for a grade to be assigned. I n programs the use of comments results in more partial credit. Read each question carefully and follow the instructions. The point values for problems may be changed at prof s discretion. Part of your grade on tests quizzes labs etc. is based not only on solving the problem you are presented with but the manner in which you solve it. For example there is a difference between two programs that meet the given specifications but one is an elegant extensible 20-line solution while the other is an obfuscated 100-line program that also meets the specifications but would be difficult to extend later. Just as your future employer would value the latter program less than the first so will I in grading your assignments. This exam counts for % of your total grade. Unless otherwise stated assume the following: The oscillator frequency is precisely 15 Mz. The code should run on a TMS320F2335 as configure on the UF F2335 Development Board without any additional peripherals. You may assume all the bit.sets that you may need have already been Good luck! done; use the standard I have used in class and on the posted web examples (e.g. BIT0 = b BIT76 = b INV7 = b INV15_6 = b). PEDGE: On my honor as a University of Florida student I certify that I have neither given nor received any aid on this examination nor I have seen anyone else do so. PRINT YOUR NAME SIGN YOUR NAME DATE (31 Mar 11) Relax! May the Schwartz be with you! Regrade comments below. Give page # & problem # and reason for the petition. Pages Available Points TOTA 100

2 University of Florida EE 4744 Spring 2011 Dr. Eric M. Schwartz Page 2/15 Exam 2 [25%] 1. The UF4744 is a new microcontroller 2 min very much like the 6C11 and 6C12 microcontrollers discussed in class. Some relevant differences are discussed here. The timing diagrams for reading and writing are given. ike the 611 and 612 the UF4744 has a timemultiplexed address/data bus. Note the two ECK-like signals on this device F1 and F2. Reset (not shown) is active-low for this device. (3%) a) Circle all the critical times on the 2 min Read Cycle and Write Cycle diagrams. abel them 1 2 etc. Describe each labeled circle below (4%) b) The entire address range of 0x9000 through 0xFFFF is available for an 3 min -bit input port (using D7-D0) and a 16-bit output port and 16k x SRAM (using D7-D0). In part c you will design a circuit to add these components. The two ports should be accessible from all addresses in the range 0x9000-0xAFFF. The SRAM should use some or all of the remaining available addresses (0xB000-0xFFFF). Fill in the below table to help you solve this problem. Do not use more address decoding than absolutely necessary i.e. use partial address decoding. InPort Addr Range: 0x9000-0xAFFF = B - B OutPort Addr Range: 0x9000-0xAFFF = B - B 16K RAM Addr Range: 0x - 0x = B - B F1 F2 R/~W A7-A0 / D7-D0 A15-A / D15-D F1 F2 R/~W A7-A0 / D7-D0 A15-A / D15-D??? A7-A0 A15-A??? A7-A0 A15-A UF4744 Read Cycle UF4744 Write Cycle D7-D0 D15-D D7-D0 D15-D

3 University of Florida EE 4744 Spring 2011 Dr. Eric M. Schwartz Page 3/15 Exam 2 (1%) 1. c) Complete the circuit diagram below in order to add the -bit input port and a 16-bit output port and 16k x SRAM described on the previous page. Please USE ABES 10 min instead of wires! Please USE ABES instead of wires! Addr 7-0 / D 7-0 Addr 15-/ D 15- R R/~W W F1 F2 Reset UF k x RAM A -A 0 D 7 -D 0 D 7-0 G -bit atch Q 7-0 D 7-0 G -bit atch Q 7-0 WE OE CS -bit Tri-State In 7-0 Out 7-0 OE -bit Tri-State In 7-0 Out 7-0 OE -bit Flip-Flop D 7 -D 0 Q 7 -Q 0 -bit Flip-Flop D 7 -D 0 Q 7 -Q 0

4 University of Florida EE 4744 Spring 2011 Dr. Eric M. Schwartz Page 4/15 Exam 2 [39%] 2. In the next several sections you will write the entire program to send a message out of the SCI-A (NOT SCI-B) serial port of your TI DSP every time (ASCII value 0x40) is 5 min received. This code should never stop executing but should be interrupt driven so that other functions could be running simultaneously. In the next several sections you will two an SCI initialization subroutines an In_Char interrupt service routine an Out_Char subroutine and Out_Msg (out message) subroutine and define all the necessary registers constants and variables. Assume that the main routine has already been written. It takes care of the EAOW the watchdog timer and setting OBJMODE. It also calls the subroutines of parts a and b i.e. INIT_SCIA and INIT_SCIA_INTR and then runs an endless loop. (5%) a) Define all the register definitions e.g. SCIACCR and also constants and variables that you will need in the subsequent sections. You may need to return to this part after completed each of the next sections of this problem. abels Instructions abels Instructions

5 University of Florida EE 4744 Spring 2011 Dr. Eric M. Schwartz Page 5/15 Exam 2 (10%) 2. b) Write an SCI-A initialization subroutine (INIT_SCIA) to turn on the transmitter turn on the receiver turn on the interrupt for the receiver use -bits of data 1 start bit 1 stop bit 15 min no parity and run at 20 kz. For this problem assume the external oscillator frequency is of the DSP is 10 Mz. Show your calculations for the baud rate related values. Also appropriately define any necessary initialization values e.g. SPCK back in part a. abels Instructions Comments

6 University of Florida EE 4744 Spring 2011 Dr. Eric M. Schwartz Page 6/15 Exam 2 (%) 2. c) Write a subroutine (INIT_SCIA_INTR) to appropriately initialize the SCI-A interrupt system for the serial receiver. This should include initializing the interrupt service routine 10 min vector the PIE and anything else necessary to be able to use the interrupt when this routine is completed. Assume the interrupt service routine is called ISR_SCIA_RX. Also appropriately define any necessary initialization values e.g. SCIA_VECTOR back in part a. abels Instructions Comments

7 University of Florida EE 4744 Spring 2011 Dr. Eric M. Schwartz Page 7/15 Exam 2 (%) 2. d) Write an interrupt service routine (ISR_SCIA_RX) to read a single character. If the character is (ASCII value 0x40) call subroutine OUT_MSG; otherwise do not 10 min call OUT_MSG. Also appropriately define any necessary initialization values back in part a. abels Instructions Comments

8 University of Florida EE 4744 Spring 2011 Dr. Eric M. Schwartz Page /15 Exam 2 (%) 10 min 2. e) Assume that a subroutine (OUT_CAR) that outputs a single character to the SCI-A transmit pin has already been written. This routine will check if the previously transmitted character has been completed; if not it keep checking until it has been completed. OUT_CAR transmits the character passed to this subroutine in the A register. Write a subroutine (OUT_MSG) to output the string (list of characters) in a table at address 0x4237. All strings will end with an end-of-string (EOS) character 0x00. (int: Use OUT_CAR in this subroutine.) Also appropriately define any necessary initialization values back in part a. abels Instructions Comments

9 University of Florida EE 4744 Spring 2011 Dr. Eric M. Schwartz Page 9/15 Exam 2 [22%] 3. An analog to digital converter (ADC) system use 4 bits and has a low reference of 1V and a high reference of 6V. Show all work in each of the problems below. (6%) a) Derive a formula to determine the voltage (in decimal) from the 4-bit ADC value (in decimal) v 10 = f( ADC 10 ). 3 min (1%) b) What is the voltage (in decimal) if ADC = ? 1 min (2%) c) What is the ADC 10 in value if v = 1.67 V? 2 min v = v = ADC = (13%) d) In lab 6 there were two suggested techniques to determine how to display the appropriate 12 min decimal values on the CD panel. You can answer either sets of questions 1-3 or 4-6 one relating to each of the two techniques. In 1-3 you assume that there is a table where the required info is stored. You will determine the voltage to be displayed with one digit to the right and one to the left of the decimal point e.g. 3.7 V. Answer the questions 1-3 dealing with this technique. OR OR OR OR OR OR OR OR In 4-6 you write programs to directly convert an ADC value to ASCII characters (displayed with one digit to the right and one to the left of the decimal point e.g. 3.7 V) in 3 steps. You will write code for each of these steps. Answer questions 4-6 dealing with this technique.

10 University of Florida EE 4744 Spring 2011 Dr. Eric M. Schwartz Page 10/15 Exam 2 (13%) 3. d) 1-3: Table ookup 12 min Assume that there is a table where the required info is stored. You will determine the voltage to be displayed with one digit to the right and one to the left of the decimal point e.g. 3.7 V 1. Assume that you are storing only ASCII values in the table. What is the minimum number of bytes abels that need to be stored for each ADC value? Describe these bytes. Instructions 2. Show the first 10 ASCII data values data for the table in a form that could be used in an assembly language program. 3. Write as assembly language program fragment to point to the value in the table corresponding to the ADC value stored in A. The resulting address should be in AR0. abels Instructions Comments

11 University of Florida EE 4744 Spring 2011 Dr. Eric M. Schwartz Page 11/15 Exam 2 (13%) 3. d) 4-6: Algorithms 14 min Write programs to directly convert an ADC value to ASCII characters (displayed with one digit to the right and one to the left of the decimal point e.g. 3.7 V) in 3 steps. You will write code for each of these steps. (If desired you can write the entire program fragment below i.e. you do not have to do it in the steps specified. Just circle this note.) 4. Write an assembly language program fragment to determine the 2-digit voltage (e.g. 37 for 3.7V) from a 4-bit ADC value. (Derive a formula for calculating the voltage and then write the code.) abels Instructions Comments

12 University of Florida EE 4744 Spring 2011 Dr. Eric M. Schwartz Page 12/15 Exam 2 3. d) 5. Write an assembly language program fragment to determine the 2 digits (in decimal) of the value determined in part 4. abels Instructions Comments d) 6. Write an assembly language subroutine to convert a 4-bit binary number (0-9 in decimal) in A to an ASCII character i.e. DEC_TO_ASCII also in A. abels Instructions Comments DEC_TO_ASCII

13 University of Florida EE 4744 Spring 2011 Dr. Eric M. Schwartz Page 13/15 Exam 2 [12%] 4. The below questions deal with an CD with the following specifications. You will write pseudo-code for this problem. Assume the following pseudo-code instructions exist: 5 min Delay(microseconds) and Write_GPIO6:0(data). For example the following might be part of your pseudo-code. Comments are helpful. Delay(10) Write_GPIO6:0(0x7F) Delay(20) Write_GPIO6:0(0x7E) // Delay 10µs for www // Comment xxx here // Delay 20µs for yyy // Comment zzz here Symbol I/O Function C/~D I Register Select 0: Data Register 1: Command Register R/~W I Read/Write 0: Data Write 1: Data Read ~E I Enable Signal Active ow DB4 I/O Bi-directional data bus line DB5 I/O Bi-directional data bus line DB6 I/O Bi-directional data bus line DB7 I/O Bi-directional data bus line GPIO 6 GPIO 5 GPIO 4 GPIO 3:0 4 UF-4744 CD C/~D R/~W ~E D 7 -D 4 Commands Codes Delay After Each Nibble 0x44 0x45 4-Bit mode initialization (NOTE: must be Note: Delay 15 ms the first command and takes two bytes) (not 10ms) between 10 ms these bytes Cursor to ome 0x0D 50 µs Cursor shift left 0x0E 50 µs Cursor shift right 0x0F 50 µs Clear display cursor to home 0x10 50 µs Move cursor to beginning of second row 0x11 50 µs Blink Cursor 0x12 50 µs C/~D R/~W CD Write Diagram ~E D7:4 10 µs Valid Data > 3 µs

14 5 min University of Florida EE 4744 Spring 2011 Dr. Eric M. Schwartz Page 14/15 Exam 2 (%) 4. a) Using the given functions write the pseudo-code to initialize the CD for 4-bit mode and cursor located at home. Pseudo-Code Comments Pseudo-Code Comments

15 5 min University of Florida EE 4744 Spring 2011 Dr. Eric M. Schwartz Page 15/15 Exam 2 (6%) 4. b) Using the given functions write the pseudo-code to display the characters U and then F. The ASCII for U is 0x55 and the ASCII for F is 0x46. The delay after each data nibble must be at least 50µs. Pseudo-Code Comments Pseudo-Code Comments