1a)[2] Connect the devices on the left column to items on the right column. Keypad 4x4

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Emery Powers
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1 2 nd Midterm ECE372 Fall 2005 This exam is: Closed book, lecture notes, calculator and internet Materials needed are in the appendix Exam duration is 75 minutes. Question Number) [Weight] I suggest that you first answer the questions where you can produce the answer quickly and then go back to more time consuming questions. Input Output 6 points 1a)[2] Connect the devices on the left column to items on the right column. Serial Terminal Shift Register Analog Signal Keypad 4x4 Memory mapped port D/A input Address/Data bus I/O port SPI A/D input SCI 1b)[4] Please complete the diagram for the 4x4 keypad below. The software will start scanning the keypad if any key is pressed; a condition that is detected with the STRA_interrrupt. Therefore you will need an additional logic gate to implement the detection of a key-press.

2 Analog to Digital 4 points You have a distance measurement apparatus, with range 0 cm to 10 cm and an output from 0 to 5[V] with 0[V] representing >=10[cm] distance. The ADC precision is 10 bits. 2a)[4] Give an expression relating the true distance to the ADC output (e.g. distance[cm]=adc[counts]*0.01[] ). Please add units. The digital value from ADC is measured in [counts]. Serial Communication, 9 points 3a)[2] What are the main functions of the asynchronous serial communication subsystem? [multiple answers] Decode the following serially transmitted bit sequence assuming 1 start bit, 8 data bits, 1 stop bit, a parity bit and that the transmitted data represents ASCII b)[1] How many characters have been transmitted? 3c)[1] What was the parity? 3d)[1] Where was there a frame error? 3e)[6] What text was sent? (partial credit for each character and for steps to determine the character)

3 Microcontroller Bus System, 16 points 4a)[2] What communication concepts do you know that can reduce the amount of physical connections between the microcontroller and external devices? [multiple answers] A new generation of microcontrollers has freely programmable digital output pins. You decide to implement an 8 bit wide databus and a 4 bit wide addressbus. 4b)[1] How many devices can you independently address? 4c)[2] What additional connections will you need between the microcontroller and the external device? [multiple correct answers possible, give one] The Microcontroller will therefore have the following lines available: -C(ontroller)_A(DDRESS) C(ontroller)_D(ATA)0..7 -Additional lines from question c) You will have the following devices attached to the microcontroller and they have the following pins: - D1_CS*, D1_OE*, D1_DATA0..7, you will connect it at address $0 - D2_CS*, D2_LE, D2_DATA0..7, you will connect it at address $1 - D3_CS*, D3_R/W*, D3_DATA0..7, D3_ADDRESS0..2, you will connect it to address $8 to $F 4d)[2] Based on the pin names what hypothetical device could they be? [multiple correct answers possible, give one]

4 4e)[3] Design the logic (address decoder) necessary to control the chip select lines (D1, 2, 3_CS*). Your answer will be a logic expression of the form D1_CS* = C_A4 & C_A2 etc. Make sure that in the future you will be able to add devices to your circuit (full address decoder). 4f)[3] Design the logic for the additional device connections (OE*, DATA, etc.) in a similar fashion. Your answer will be a logic expression. 4g)[3] Simplify your address decoder (=partial address decoder) so that the system can independently address the proposed devices with the least amount of hardware but will need to be redesigned if you would want to add additional components at later time. [multiple answers possible, give one]

5 Design of Integrated Microcontroller Subsystems, 13 points 5a)[2] What are the main functions of the timer subsystem? [multiple answers] 5b)[2] What are the main functions of the analog input subsystem? [multiple answers] 5c)[2] What are the main functions of the synchronous serial communication subsystem? [multiple answers] You are about to design an analog output component that will be integrated into a future generation of microcontroller. 5d)[1] In your opinion, what is the most common application of an analog output in microprocessor based systems? [multiple correct answers possible, give one] 5e)[6] Based on the general concept present in most microcontroller subsystems such as the HC12, what functions and registers will you propose? [multiple correct answers possible, give one]

6 Appendix ASCII and OPCODE Tables

EE251: Thursday November 30

EE251: Thursday November 30 Course Evaluation Forms-fill out Memory Subsystem continued Timing requirements Adding memory beyond 4 Gbyte Time Allowing: Begin Review for Final Exam Homework due next Tuesday,