Iraq University College Dept. of Communication and Computer Engineering Subject: Digital Electronics Second Semester Exam: Final 2016-2017 Class: Third Year Examiner: Ali M. Jasim Time: 120 Minutes Notes: (1) Answer Four Questions Only. (2) Max. mark 40%,10% for each question. Q1] Answer the following questions: A: Briefly explain each one of the following abbreviations: 1. SPI 2. 12C 3. UART 4. L.IN B: A certain microcontroller unit has 12-bit D/A converter. Determine the percentage resolution of the D/A converter. Q2] Design an MCU-based low pass filter for filtering musical sound signal. The input of an A/D converter of the MCU is an analog signal (x) taken from any sound player device. This analog signal should be filtered by a low pass digital filter with 800Hz cutoff frequency. The difference equation of the filter is given by the following equation: y(n)=0.01497[x(n)+13.36005x(n1)+x(n2)] Where y(n) is the output filtered signal, x(n) is the input digital signal, n represents the sample number. Q3] Answer the following questions: A: Design an MCU based system to control the speed and direction of 4-phase stepper motor. The speed cannot exceed 60RPM and it is adjusted using potentiometer, where the range on potentiometer is 0 to 5v. The direction is selected using simple switch. The motor has 200 steps per revolution. B: Design an MCU based system to control 220VAC lamp based on the motion that is detected by using PIR motion sensor. Q4] Design a simple line follower car robot using Arduino board and three IR sensors. This robot has the capability to deteet a black/dark line on a surface depending on the contrast. IR sensors are used as the line detecting sensors for the project. Then, the data from the IR sensors will be given to Arduino board and it gives corresponding signals to the motor driver IC. 1.2