Microcontrollers: As name suggest is a single baby computer on a single integrated circuit containing various other elements.
This paper consists of two sections, namely Section A and Section B. Section A consists of 10 questions carrying 2 marks each and Section B consists of 6 questions carrying 10 marks each. All the questions are compulsory.
TIME : 3 Hrs.
NOTE: All the questions of Section-A is compulsory and from Section-B any 5.
SHORT QUESTIONS: ( each 2 marks)
1. What do you mean by the term embedded controllers ?
Ans: The devices that has all the functional blocks on chip, including the program and data memory and there is no external data/address bus provided. For example, ATMEL89C2051.
2. Discuss the advantages of microcontrollers over microprocessors in control applications?
Ans: The first main advantage is that the ALUs can be assembled together horizontally to form computers that can handle very large data at a time. Another advantage is bit slice design that makes use of possible bipolar chip technology that is very fast.
3. What are RISC and CISC processors?
Ans: RISC chips requires lesser hardware implementations, which makes them simpler to design and hence lesser costs of production.
4. Discuss the criteria for selecting a microcontroller device.
Ans: It must have ram and rom to support its inbuilt functions. It must have +5v supply, must be fast and should have programmable and data memory.
5. List few features of 8051 microcontroller?
Ans: – Operating frequency is 12mhz, separate 64k program and 64k data memory, multiply and divide instructions has a boolean processor
6. Discuss the advantages and disadvantages of Harvard and Von Neuman architectures.
Ans: Harvard architecture uses separate memories for program and data memory whereas Von Neuman uses same program and data memory.Therefore Harvard is faster compared to other one.
7. What is the purpose of ALU ?
Ans: ALU performs arithmetic and logical operation on 8- bit operands. Accumulator is the register which gets the output of the ALU in most of the arithmetic and logical operations.
8. Name 2 register that consists of 16 bit.
Ans: Program counter and Data pointer
9. Name few general purpose registers
Ans: Accumulator, B-register, R0- R7
10. What are SFR?
Ans: The 128 bytes of on-chip additional RAM locations from 80H to 0FFH are reserved for the special functions and therefore these are called as special function register.
LONG QUESTIONS: (each 10 marks)
1. List all the registers used in 8051 microcontroller in brief.
Ans: General purpose register: Accumulator, B-registers and four register banks may be used as general purpose registers.
Accumulator:Similar to any microprocessor like 8085, MCS-51 has an 8- bit accumulator. Accumulator is used by all the arithmetic and logical instructions.
B-register: B- register is an 8- bit wide register. It is available as general- purpose register when it is not being used by multiplication and division operations.
Stack pointer:Stack pointer of 8051 is a 8 bit wide. It is incremented during push or call operation and is decremented during pop or return operation.
Special function register: The 128 bytes of on-chip additional RAM locations from 80H to 0FFH are reserved for the special functions and therefore these are called as special function register.
Program Status Word: PSW is an 8 bit register . It consists of auxillary flag, overflow flag, parity flag.
DPTR (Data pointer):: It is 16 bit register consisting of two types DPH and DPL . One with data pointer high and other data pointer low.
Timer register: Register pairs th0 , tl0, th1, tl1.
Control registers: TCON, TMOD, IE,IP, SCON, PCON contain the control and status for interrupts, serialy and timer/ counters.
Capture register:: RCAP2H – RCAP2L are the capture registers.
2. Draw the pin diagram of 8051 microcontroller.
3. Draw the memory organisation of mcs – 51.
4. What are all addressing modes of mcs-51?
Ans: There are five addressing modes in 8051 which are as follows:-
1. Register Addressing: In this registers r0 to r7 from the selected register bank, accumulator, b- register, carry bit and dptr are used.
2. Direct Addressing: In this, direct address of the operand is specified in the instruction itself. Direct addressing mode uses the lower 128 bytes of internal RAM and the special function registers.
3. Register-Indirect Addressing:
It uses any one of the registers R0 to R7 from the selected register bank, as pointer to the location in the 256 bytes of data memory.
4.Immediate Addressing: Immediate addressing allows using immediate data as a part of the instructions.
5. Base register and index register: This mode allows a byte to be accessed from the program memory, whose address is calculated as the sum of a base register and index register.
5. Enlist the various flags in the PSW register.
Ans: The various flag used in PSW register is as follows:-
6. Draw the block diagram of 8051 microcontroller
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