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VTU Electronics and Communication Engineering (Semester 4)
Microcontroller for Embedded Systems
June 2012
Total marks: --
Total time: --
INSTRUCTIONS
(1) Assume appropriate data and state your reasons
(2) Marks are given to the right of every question
(3) Draw neat diagrams wherever necessary

1 (a) Explain briefly the Harvard and Von-Neumann CPU architecture.
6 M
1 (b) Sketch the internal block schematic of 8051, list its salient features and briefly explain its register set.
10 M
1 (c) Briefly explain the dual functions of port-3 pins of 8051.
4 M

2 (a) Briefly explain any four addressing modes of data of 8051 with an example for each.
6 M
2 (b) Explain the operations of the 8051 instructions:
i) RLC A
ii) DA A
iii) MUL AB and
AJMP addr
8 M
2 (c) Write an ALP (assembly language program) in 8051 to count the number of positive and negative numbers present in the internal memory block starting with the address 20H, containing N byte, Store the counts after the last data byte in the memory block.
6 M

3 (a) Briefly explain the different assembler directives used in an assembly language program.
4 M
3 (b) Write an 8051 ALP to find the value of NI/RI using a subroutine that calculates the the factorial of a given number. Assume the values of N and R are stored in locations 10H and 11H. Store the value of NI/RI in 12H. Assume NI?RI and NI/RI are all maximum 8 bit values.
10 M
3 (c) Write an 8051 software time delay subroutine to generate a time delay of 100 μsec when called. Assume crystal frequency as 12 MHz. Show delay calculations. Do not use timers.
6 M

4 (a) Interface an LCD display unit to 8051 and write an ALP to display the message 'DONE'.
10 M
4 (b) Interface a stepper motor to 8051and rotate it by checking the statue of a simple toggle switch connected to pin P2.0 as follows:
i) If switch is open rotate motor in clock wise direction.
ii) If switch is closed rotate motor in counter clockwise direction.
10 M

5 (a) With regard to the interrupt of 8051.
i) Give the vector address of the interrupts.
ii) Briefly explain the procedure of enabling / disabling the entire interrupt system and enabling / disabling of individual interrupts.
iii) Indicate the default priority on reset and procedure to alter this default priority.
6 M
5 (b) With regard to timer of 8051,
i) Explain briefly the difference between the timer and counter operation modes.
ii) Indicate how to start / stop the timer if GATE control is also used.
iii) Explain mode -2 operation.
6 M
5 (c) Write an ALP in 8051 to generate a square wave of frequency 5 kHz on pin P2.7 using Timer-I in interrupt mode. Assume crystal frequency as 11.0592 MHz.
8 M

6 (a) i) Explain briefly the asynchronous serial communication format.
ii) Indicate steps of programming 8051 to transmit a character and receive a character serially.
9 M
6 (b) Write a 8051 C program to transmit the character '*' continuously serially in the 8 bit, I start bit, 1 stop bit, 2400 baud rate format. Assume the crystal frequency as 11.0592 MHz.
8 M
6 (c) What is the advantages of using the chip 8255 with 8051? Indicate the functions of the pins A0 and A1 of 8255.
3 M

7 (a) Explain the architecture of MSP430 with its internal block schematic
10 M
7 (b) Give the details of memory map of MSP430.
6 M
7 (c) Write a note on block system of MSP430.
4 M

8 (a) Write an assembly program to generate a waveform with ON time of 7msec and OFF time of 21 msec on P0.5. Assume XTAL of 11.0592 MHz. Use timer 0.
12 M
8 (b) Explain the bits of SOON register.
8 M

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