Electronics 1 : Important Questions : SYBCS

Chapter 1: Basics of Microcontroller & Intel 8051 Architecture

1 mark

Q. What is the function of ALE pin of 8051 ?

Q. Write the function of Pin PSEN .

-Q. Mention Onchip ROM capacity of 8051.

Q. What is the capacity of internal ROM of 8051?

-Q. What is the value of stack pointer register of 8051 on reset?

Q. What is meant by a microcontroller?

Q. Mention any two differences between controller and processor.

Q. What is the use of bit TR1 in TCON register ?

Q. What is the value of program counter after power on reset ?

2 mark

Q. Draw structure of a port pin and explain how reading and writing operation is performed using port pins ?

-Q. Explain the internal RAM organization of 8051 microcontroller..

Q.Write 8051, C-program to generate square wave on P2.5 having 2 kHz frequency and 50% duty cycle. Assume XTAL freq. = 12 MHz (The value to be loaded into timer register FF06H) [Use Timer 1 in Mode 1.]

Q.Explain any five features of 8051 µC.

Q. Explain the function of following pins of 8051 microcontroller.

 i) RESET 

ii) ALE 

iii) EA 

iv) PSEN 

v) XTAL 1 and XTAL 2

5 mark

Q. Draw block diagram of 8051 microcontroller architecture and explain any three blocks of it.

-Q. Write any five differences between microcontroller and microprocessor.

Q. Explain dual role of Port 0 and port 2 of 8051 microcontroller.

Chapter 2 : Instructions of 8051

1 mark

Q. What is the function of INC and DPTR instruction ?

Q. State any two addressing modes.

Q. Give two unconditional jump instructions with proper syntax.

Q. What is function of Assembler directive "Org"?

Q.  Define the term: assembler directive.

Q.Name the addressing mode for the instruction MOV DPTR, # 3000 H.
Q. Identify the addressing mode of 8051 instruction MOV A, @ R1.

Q. What is the difference between instructions MOV R1, 41H and MOV R1, # 41H ?

Q.What is the status of bit P1.1 after execution of instruction SET B P1.1 ?

 2 mark

----Q. Explain the functions of the following instructions :

(i) MOV A, @ RO 

(ii) ADD A, # 80H 

(iii) RL A 

(iv) SWAP A 

(v) CPL bit.

(i) NOP 

(ii) ANL A, R5 

(iii) MOVA,@ R0 

(iv) SETB P1.6 

(v) JNZ addr. 

i) CLR A 

ii) ORL A, # 75 H 

iii) LCALL 2000 H 

iv) SETB PSW. 4 

v) MUL AB

(i) MOV A, 40 H 

(ii) AIMP addr 11 

(iii) CPLA 

(iv) INC R1 

(v) MUL AB 

5 mark

Q. Explain different addressing modes of 8051 microcontroller with suitable example.

Q. What will be the output of each of the following ofter execution ? 

(i) P1 = O × FO & O × 35 

(ii) P1 = O × FF
O × 65 

(iii) P2 =
O × IF 

(iv) P2 = O × 36 | O × 65 

(v) P1 = O × 12 >> 2

Chapter 3: Programming 8051 in CC

2 mark

Q.Write an 8051 assembly language program for blinking of 8 LEDS connected to port 2.

5 mark

Q. Write a program to read the status of switch connected to P2.0 if it is ‘O’ switch off the LED connected to P1.7.

Q. Explain how LED can be interfaced to port P1.2 of 8051 µC with neat diagram. Write a program to blink the LED.

Q.Explain how LED can be interfaced to 8051 with a neat diagram and write a program to toggle LED connected to P1.3 continuously.

Q.Which port of 8051 requires external pill up resistors? Draw a block diagram interfacing common anode SSD to port 2.

Chapter 4 : Timer, Counter and Interrupts

1 mark

Q. Which special function register of 8051 is used to keep track of priority of interrupts?

Q. What is the significance of Gate bit of TMOD register?

Q.  State the role of C/T bit in TMOD register.

Q. Which is the highest priority interrupt in 8051 ?

Q. Write full form of IVT and ISR with respect to interrupts of 8051 microcontroller.

Q. What is the use of bit TR1 in TCON register ?

Q. What is the significance of timer flag (TF) in 8051 ?

Q. Give the use of SMOD bit in PCON register.

2 mark 

Q. Write an 8051 C- program for generating a pulse on pin P 3.2 using timer 1 in mode 1.

Q. Explain the interrupts of 8051 µC.

5 mark

Q. Write an assembly langauge program to toggle all pits of Port 2 continuously.

Q. Explain the sequence of actions carried out by 8051 microcontroller when an interrupt occurs.

-Q. Draw bit format of Interrupt Enable (IE) register and explain function of each bit.

Q. Write the types of interrupts of 8051. Mention the vector addresses of these interrupts.

Q. Draw a bit format of Tmod register and explain function of each bit.

Chapter 5: Interfacing and Serial Communication

1 mark

Q. List any two registers used for serial communication.

---Q. Which pin of LCD is used to control the contrast?

Q. Define step angle of stepper motor.

Q. What is the maximum input voltage which can be applied to ADC 0804 if Vref /2 = 2V.

Q.What is the step size of 8 bit ADC if Vref = 4.5 volt ?

Q. What is the step size of 8-bit ADC, if Vref = 2.56 V.

2 mark

Q. Draw block diagram for interfacing DAC with 8051 and write ‘C’ program to generate triangular wave.

Q. Write 8051 c-program to rotate a stepper motor connected to port 1 in clockwise direction continuously.

5 mark

Q.Give differences between asynchronous and synchronous serial communication.

-Q.Draw a neat diagram of interfacing stepper motor to 8051 microcontroller and write C program to run the motor.

Q. Draw a neat diagram of interfacing 8-bit ADC (analog to digital converter) to 8051 microcontroller and write ‘C’ program to run this interface.

Q. Draw a neat diagram to show how LCD is interfaced to 8051. Write a ‘C’ program to display the message “ELECTRONICS”.

Q. Draw a block diagram of interfacing DAC to port 1 of 8051 microcontroller. Write a C- program to generate triangular waveform.

Q. Draw the control word format of TCON register of 8051. Explain the significance of each bit of the register.

Q. Write 8051, C program to generate square wave on P1.5 having 1000 Hz frequency and 50% duty cycle. Assume crystal frequency of 12 MHz and given a value to be loaded into timer register is (FEOC)HEX. Use timer 1 in mode 1.

Q.Write a C program to generate a 5 kHz square wave of 50% duty cycle on port P2.2 line using timer 1, mode 1. Assume crystal frequency = 11.0592 MHz.

Q. Draw a schematic to show how a DAC can be interfaced to 8051. Write a ‘C’ program to generate a sawtooth waveform.

Chapter 4: Timer, Counter and Interrupts

Chapter 5: Interfacing and Serial Communication