Two Marks Questions with Answers

Two Marks Questions with Answers

 

Q.1    Write the vector address and priority sequence of 8051 interrupts ?

(Refer section 16.7.2)

Q.2    What is the function of SM2 bit in the SCON register of 8051 ?

(Refer section 16.6)

Q.3    Name the interrupts available in microcontroller 8051.

(Refer section 16.7)

 

Q.4    Write a delay routine for 1 millisecond using timer 0 of 8051 for 12 MHz crystal frequency.

Ans. : Crystal frequency = 12 MHz

T = 12 / 12 × 10⁶ = 1µs

i.e. the counter counts up every 1 ps. Out of many 1 µs intervals, we have to make a 1 µs delay.

We need 1 ms/1 µs = 1000 clocks

N = 65536 - 1000 = 64536 = FC18H

We have to load TH with FCH and TL with 18H.

Program :

DELAY : MOV TMOD, # 10H        ; Timer 1, Model

MOV TL1, # 18H ; TL1 = 18H, Timer 1 lower byte register

MOV TH1, # FCH         ; TH1 = FCH, Time 1 higher byte register

SETB TR1 ; Start timer 1

REPEAT : JNB TRI, REPEAT ; Monitor timer flag 1 till it becomes 1.

CLR TR1 ; stop timer 1

CLR TF1 ; Clear time 1 flag

RET ; Return to main program

 

Q.5 Explain the register IE format of 8051.

(Refer Fig. 16.7.2)

 

Q.6 List the interrupt sources in 8051 microcontroller.

Ans. : The interrupts are :

 

Q.7 How the RS-232C serial bus is interfaced to TTL logic device ?

Ans. : The RS-232C signal voltage levels are not compatible with TTL logic levels. Hence for interfacing TTL devices to RS-232C serial bus, level converters are used. The popularly used level converters are MC 1488 and MC 1489 or MAX 232.

 

Q.8 Define SBUF register in 8051 and mention its use.

Ans. : SBUF is an 8-bit register dedicated for serial communication in 8051. Its address is 99H. It can be addressed like any other register in 8051. Writing to SBUF loads data to be transmitted and reading SBUF accesses received data.

 

Q.9 Explain the use of interrupt enable register in 8051 microcontroller.

Ans. : The interrupt enable register in 8051 microcontroller allows individually enabling and disabling of all interrupt sources in 8051.

 

Q.10 What register keeps track of interrupt priority in the 8051 ? Explain.

Ans. : Interrupt priority control registers keeps track of interrupt priority in the 8051.

Each interrupt source can also be individually programmed to one of two priority levels by setting or clearing a bit in interrupt priority control register.

A low-priority interrupt can itself be interrupted by a high-priority interrupt, but not by another low priority interrupt. A high-priority interrupt can't be interrupted by any other interrupt source.

 

Q.11 Mention the registers used for serial communication in 8051 microcontroller.

(Refer section 16.6)

 

Q.12 Write the function of TMOD register in 8051 microcontroller. AU : Dec.-15

(Refer section 16.3.1)

 

Q.13 Explain the interrupts of 8051 microcontroller.

(Refer section 16.7)

University Questions with Answers (Long Answered Questions)

 

(Regulation 2008)

May-11

Q.1 Describe the different modes of operation of timers in 8051.

 (Refer section 16.4) [16]

Q.2 Explain the interrupt structure with the associated registers in 8051 microcontroller.

(Refer section 16.7) [8]

Dec.-11

Q.3 Draw the TMOD register format and explain.

(Refer section 16.3) [4]

Q.4 Describe the different modes of operation of timers in 8051.

(Refer section 16.4) [16]

Q.5    Describe how the serial communication is performed in 8051.

(Refer section 16.6) [8]

Q.6    Draw the flowchart for programming of serial port of 8051.

(Refer section 16.6) [2]

May-12

Q.7 Explain the different operating modes of timer in 8051 microcontroller.

(Refer section 16.4) [8]

Dec.-12

Q.8 Explain the interrupt structure of 8051 microcontroller.

 (Refer example 16.7)   [8]

May-13

Q.9 Explain the vectored interrupts in 8051 microcontroller.

(Refer section 16.7) [8]

Dec.-13

Q.10 Discuss about the timers in 8051 with suitable examples.

(Refer section 16.3) [16]

May-14

Q.11 Explain the port operation in 8051 microcontroller.

(Refer section 16.1) [16]

Q.12 Describe the different modes of operation of timers in 8051.

(Refer section 16.4) [16]

Dec.-14

Q.13 Explain interrupt structure of 8051 in detail.

(Refer section 16.7) [16]

 (Regulation 2013)

Dec.-15

Q.14 Explain the timers of 8051 microcontroller with appropriate diagrams.

(Refer section 16.4) [16]

Q.15 Explain the I/O ports and their functions of 8051 microcontroller.

(Refer section 16.1) [16]

May-16

Q.16 Explain the vectored interrupts in 8051 microcontroller.

(Refer section 16.7.2)    [8]

Dec.-16

Q.17 Explain the I/O ports of 8051 microcontroller in detail.

(Refer section 16.1) [16]

Q.18 Explain the interrupt structure of 8051 microcontroller.

(Refer section 16.7) [8]

May-17

Q.19 Explain timer modes of 8051 microcontroller.

(Refer section 16.4) [16]

Dec.-17

Q.20 Discuss in detail, the hardware and software support provided by 8051 for serial communication.

(Refer section 16.6)       [13]

May-18

Q.21 Briefly discuss the ports of 8051, internal circuits and its functions in detail.

(Refer section 16.1) [13]