Explain following instructions of 8051. (i) ADDC (ii) L CALL

Explain following instructions of 8051. (i) ADDC (ii) L CALL
by

1 Answer

Answer :

(i) ADDC: The ADDC instruction adds a byte value and the value of the carry flag to the accumulator. The results of the addition are stored back in the accumulator. Several of the flag registers are affected. 

ADDC

Function: Add with Carry

Syntax: ADDC A, source byte

Flags affected: OV,AC,CY

Description: ADDC simultaneously adds the byte variable indicated, the carry flag and the Accumulator contents, leaving the result in the Accumulator (A = A + byte +CY). The carry and auxiliary-carry or bit flags are set, respectively. If CY = 1 prior to this instruction, CY is also added to A.

Addressing modes supported for ADDC instruction :

* Immediate: ADDC A,#data

* Register: ADDC A, Rn

* Direct: ADDC A, address

* Register Indirect: ADDC A, @Ri

(ii) LCALL

Function: Long call, Transfers control to a subroutine

Syntax: LCALL 16 bit addr

Flags affected : None

No. of bytes used: 3 byte( 1 byte is opcode and other two bytes are the 16 bit address of the target subroutine)

Description: This instruction is used to transfers control to a subroutine To reach the target address in the 64 Kbytes maximum ROM space of the 8051, LCALL instruction is used. For calling a subroutine, the PC register (which has the address of the instruction after the LCALL) is pushed onto the stack, and the stack pointer (SP) is incremented by 2. Then the program counter is loaded with the new address and control is transferred to the subroutine. 
by

Related questions

Explain function of following pins of 8051 (i) Pin 31 (ii) Pin 29 (iii) Pin 21-28

Description : Explain function of following pins of 8051 (i) Pin 31 (ii) Pin 29 (iii) Pin 21-28 

Last Answer : i) Pin 31-EA : It is and active low I/P to 8051 microcontroller. When (EA)= 0, then 8051 microcontroller access from external program memory (ROM) only. When (EA) = 1, then it access internal ... /Output, when external memory is interfaced, PORT 2 pins act as the higher-order address bus. (A8-A15)

Draw the format of PSW register of 8051 microcontroller and explain the function of each bit.

Description : Draw the format of PSW register of 8051 microcontroller and explain the function of each bit.

Last Answer : 1. CY: Carry flag. This flag is set whenever there is a carry out from the D7 bit after an 8 bit addition or subtraction. It can also be set to 1 or 0 directly by instructions such as SETB C and ... the A register contains an odd number of 1s, then P=1. P=0 if A has an even number of 1s.

Draw and explain Internal port structure of Port 0 and Port 1 of 8051 microcontroller.

Description : Draw and explain Internal port structure of Port 0 and Port 1 of 8051 microcontroller.

Last Answer : Port-0 can be configured as a normal bidirectional I/O port or it can be used for address/data interfacing for accessing external memory. When control is '1', the port is used for address/data ... is not able to sink the current the pin voltage may rise, leading to a possible wrong reading.

Explain with sketch the interfacing of 4 ×4 matrix keypad with 8051 microcontroller.

Description : Explain with sketch the interfacing of 4 ×4 matrix keypad with 8051 microcontroller.

Last Answer : Interfacing keypad Fig. shows how to interface the 4 X 4 matrix keypad to two ports in microcontroller. The rows are connected to an output port and the columns are connected to an input port. To ... key has been pressed, the next task is to find out which column the pressed key belongs to.

Describe serial communication in 8051. Explain the use of SCON register.

Description : Describe serial communication in 8051. Explain the use of SCON register.

Last Answer : 8051 micro controller communicate with another peripheral device through RXD and TXD pin of port3.controller have four mode of serial communication.  1. Serial Data Mode-0 (Baud Rate Fixed) In this mode ... .0 Receive interrupt flag. Set by hardware halfway through the stop bit time in mode 1. 

Explain processes of interrupt enabling and disabling in 8051.

Description : Explain processes of interrupt enabling and disabling in 8051.

Last Answer : Interrupts are the events that temporarily suspend the main program, pass the control to the external sources and execute their task. It then passes the control to the main program where it had left off. ... interrupts. Its bit sequence and their meanings are shown in the following figure.

Draw and explain the interfacing of DAC to 8051.

Description : Draw and explain the interfacing of DAC to 8051.

Last Answer : Diagram:  * Microcontroller generates output which is in digital form but many controlling system requires analog signal as they don't accept digital data thus making it necessary to use DAC ... current. Hence we require an I to V converter to convert this current into equivalent voltage. 

Describe power down mode and ideal mode of 8051 with circuit diagram . which SFR is used to set these modes and draw the same.

Description : Describe power down mode and ideal mode of 8051 with circuit diagram . which SFR is used to set these modes and draw the same.

Last Answer : IDLE MODE In the Idle mode, the internal clock signal is gated off to the CPU, but not to the Interrupt, Timer and Serial Port functions. The CPU status is preserved in its entirety, the Stack Pointer, ... t change on chip RAM PCON (Power Control Register) SFR is used to set these modes.

State any four important features of 8051 microcontroller.

Description : State any four important features of 8051 microcontroller.

Last Answer : Features of 8051 microcontroller:  1) 8- bit data bus and 8- bit ALU. 2) 16- bit address bus - can access maximum 64KB of RAM and ROM. 3) On- chip RAM -128 bytes (Data ... 0 and Timer 1, two external hardware interrupts- INT0 and INT1, Serial communication interrupt for both receive and transmit.

State the alternate pin functions of port 3 of 8051.

Description : State the alternate pin functions of port 3 of 8051.

Last Answer :  the alternate pin functions of port 3 of 8051 :

Draw interfacing of 16 × 2 LCD with 8051 and state the function of EN and RS of LCD

Description : Draw interfacing of 16 × 2 LCD with 8051 and state the function of EN and RS of LCD

Last Answer : Diagram: RS: RS is the register select pin. We need to set it to 1, if we are sending some data to be displayed on LCD. And we will set it to 0 if we are sending some command instructions ... the LCD to latch in the data present at the data pins. This pulse must be a minimum of 450ns wide.

Draw the format of TCON register of 8051 and describe the function of each bit of it.

Description : Draw the format of TCON register of 8051 and describe the function of each bit of it.

Last Answer : TCON: TIMER/COUNTER CONTROL REGISTER.BIT ADDRESSABLE  TF1 TCON. 7 Timer 1 overflows flag. Set by hardware when the Timer/Counter 1 Overflows. Cleared by hardware as processor ... 0 type control bit. Set/cleared by software to Specify falling edge/low level triggered External Interrupt

Describe 8051 microcontroller as boolean processor.

Description : Describe 8051 microcontroller as boolean processor.

Last Answer : * 8051 processor is a CPU that can perform some operation on a data and gives the output. * The 8051 processor contains a complete Boolean processor for single-bit operations. * The internal RAM contains 128 ... CLR C means clear the carry bit SETB 20h means set the memory bit with bit address 20h.

List SFR in 8051.

Description : List SFR in 8051.

Last Answer : ACC and B registers - 8 bit each DPTR : [DPH:DPL] - 16 bit combined PC : Program Counter - 16 bits Stack pointer SP - 8 bit PSW : Program Status Word Port Latches ... , serial control Timer Registers (TCON,TMOD,TL0/1,TH0/1) Power control Interrupt Enable, Interrupt Priority

List specifications of 8051 microcontroller.

Description : List specifications of 8051 microcontroller.

Last Answer : 1) 8- bit data bus and 8- bit ALU. 2) 16- bit address bus - can access maximum 64KB of RAM and ROM. 3) On- chip RAM -128 bytes (Data Memory) 4) On- chip ROM - 4 KB ( ... 0592 MHz 9) Has power down and idle mode in microcontroller when no operation is performed. 10) Six interrupts are available.

List out any two instructions of following addressing modes: (i) Immediate addressing. (ii) Register addressing.

Description : List out any two instructions of following addressing modes: (i) Immediate addressing. (ii) Register addressing.

Last Answer : (i) Immediate addressing instructions: 1. MOV A, #36H 2. MOV DPTR, #27A2H (ii) Register addressing. 1. MOV A, R0 2. MOV R7, A

Explain the following instructions. SWAP A ADD C MUL AB CJNE A, add, radd MOV A, R0 MOVX A, @ A + DPTR.

Description : Explain the following instructions. SWAP A ADD C MUL AB CJNE A, add, radd MOV A, R0 MOVX A, @ A + DPTR.

Last Answer : SWAP A Description: This instruction exchanges bits 0-3 of the Accumulator with bits 4-7 of the Accumulator. This instruction is identical to executing "RR A" or "RL A four times ... referred to as the base address and the accumulator value is referred to as the index address.

State and explain the need of the following development tools microcontroller board: (i) Editor (ii) Assembler (iii) Compiler (iv) Linker

Description : State and explain the need of the following development tools microcontroller board: (i) Editor (ii) Assembler (iii) Compiler (iv) Linker

Last Answer : 1) Editor: An editor is a program which helps you to construct your assembly language program in right format so that the assembler will translate it correctly to machine language. So, you can type your ... . Some examples of linker are ASEM-51 BL51, Keil u Vision Debugger, LX 51 Enhanced Linker etc

Explain the use of following assembler directives. (i) EQU (ii) ORG

Description : Explain the use of following assembler directives. (i) EQU (ii) ORG

Last Answer : (i) EQU: Equate It is used to define constant without occupying a memory location. Syntax: Label EQU Numeric value By means of this directive, a numeric value is replaced by a symbol. For e.g. ... decimal. If the number is notfollowed by H, it is decimal and the assembler will convert it to hex.

Differentiate between (i) Harvard and Von-neuman architecture (ii) Microprocessor and Microcontroller

Description : Differentiate between (i) Harvard and Von-neuman architecture (ii) Microprocessor and Microcontroller

Last Answer : i) Harvard Architecture and Von-neuman architecture ii) Microprocessor and Microcontroller

Explain the various selection factors of microcontroller suitable for application.

Description : Explain the various selection factors of microcontroller suitable for application.

Last Answer : The selection of microcontroller depends upon the type of application. The following factors must be considered while selecting the microcontroller.  1. Word length: The word length of ... and for lesser production EPROM version or CPU version with external program memory is suitable

In 8051,After reset the SP register is initialized to address________. a. 8H b) 9H c) 7H

Description : In 8051,After reset the SP register is initialized to address________. a. 8H b) 9H c) 7H

Last Answer : c) 7H

In 8051 an external interrupt 1 vector address is of ________ and causes of interrupt if ____. a) 000BH, a high to low transition on pin INT1 b) 001BH, a low to high transition on pin INT1 c) 0013H, a high to low transition on pin INT1 d) 0023H, a low to high transition on pin INT1

Description : In 8051 an external interrupt 1 vector address is of ________ and causes of interrupt if ____. a) 000BH, a high to low transition on pin INT1 b) 001BH, a low to high transition on pin INT1 c) 0013H, a high to low transition on pin INT1 d) 0023H, a low to high transition on pin INT1

Last Answer : a) 000BH, a high to low transition on pin INT1

SP of 8051 is of ___ wide and it is loaded with the default value of ___ after reset. a) 2 byte, 08H b) 8 bit, 07H c) 1 byte, 09H d) 8 bit, 06H

Description : SP of 8051 is of ___ wide and it is loaded with the default value of ___ after reset. a) 2 byte, 08H b) 8 bit, 07H c) 1 byte, 09H d) 8 bit, 06H

Last Answer : d) 8 bit, 06H

In 8051 which interrupt has highest priority? a)IE1 b)TF0 c)IE0 d)TF1

Description : In 8051 which interrupt has highest priority? a)IE1 b)TF0 c)IE0 d)TF1

Last Answer : a)IE1

The 8051 microcontroller is of ___pin package as a ______ processor. a) 30, 1byte b) 20, 1 byte c) 40, 8 bit

Description : The 8051 microcontroller is of ___pin package as a ______ processor. a) 30, 1byte b) 20, 1 byte c) 40, 8 bit

Last Answer : c) 40, 8 bit

In 8051 which interrupt has highest priority? a)IE1 b)TF0 c)IE0 d)TF1

Description : In 8051 which interrupt has highest priority? a)IE1 b)TF0 c)IE0 d)TF1

Last Answer : c)IE0

The 8051 microcontroller is of ___pin package as a ______ processor. a) 30, 1byte b) 20, 1 byte c) 40, 8 bit d) 40, 8 byte

Description : The 8051 microcontroller is of ___pin package as a ______ processor. a) 30, 1byte b) 20, 1 byte c) 40, 8 bit d) 40, 8 byte

Last Answer : c) 40, 8 bit

List out features of any four addressing modes of 8051.

Description : List out features of any four addressing modes of 8051.

Last Answer : 1.Immediate addressing mode: In this Immediate Addressing Mode, the data is provided in the instruction itself. The data is provided immediately after the opcode. These are some examples of Immediate Addressing Mode. MOVA ... us see some examples of this mode. MOV 0E5H, @R0 MOV @R1, 80H

Which instruction of 8051 microcontroller is used for reading data from code memory?

Description : Which instruction of 8051 microcontroller is used for reading data from code memory?  A) Mov B) MOVC C) MOVX D) XCH

Last Answer : Mov

Define the term BUS related to microprocessor/controller and list different buses used in microcontroller.

Description : Define the term BUS related to microprocessor/controller and list different buses used in microcontroller.

Last Answer : BUS: A Bus is a set of physical connections used for communication between CPU and peripherals. Different buses used in microcontroller are: 1. Address Bus 2. Data Bus 3. Control Bus

Draw the format of SCON register.

Description : Draw the format of SCON register.

Last Answer : SM0 SCON.7 Serial port mode specifier SM1 SCON.6 Serial port mode specifier SM2 SCON.5 Used for multiprocessor communication (Make it 0.) REN SCON.4 Set/ cleared by software to enable/ ... flag. Set by hardware halfway through the stop bit time in mode 1. Must be cleared by software.

Find out the number of address lines required to access 4 KB of RAM

Description : Find out the number of address lines required to access 4 KB of RAM

Last Answer : 12 address lines required to access 4 KB of RAM as  212 = 4KB 

Describe with sketches the procedure to troubleshoot the traffic light controller.

Description : Describe with sketches the procedure to troubleshoot the traffic light controller.

Last Answer : Considerations of Traffic Signal  1) Traffic light may have sensors integrated to provide real time traffic information  2) Based on the traffic information provided by the sensor, the duration of the ... 8) Capacity analysis of the intersection for current and future years using growth

Develop Assembly Language program (ALP) to find the largest number in a block of 10 numbers stored at location 40H onwards in internal RAM.

Description : Develop Assembly Language program (ALP) to find the largest number in a block of 10 numbers stored at location 40H onwards in internal RAM.

Last Answer : ORG 0000H MOV R1, #0AH ; Initialize Byte Counter MOV R0, #40H ; Initialize source pointer R0 to 40H DEC R1 ; decrement counter by one MOV 60H, @R0 ;Read First Byte UP: INC R0 ; Increment the ... MOV A,B MOV 50H, A ; store result at memory location 50H(Assume any location) HERE: SJMP HERE

State features of ADC 0808.

Description : State features of ADC 0808.

Last Answer : 1. Easy to interface with all Microprocessors or works Stand alone. 2. Eight channel 8-bit ADC module. 3. Can measure up to 8 Analog values. 4. On chip Clock not available, external Oscillator ... (Clock). 5. Digital output various from 0 to 255, operating power is 15mW, conversion time 100us.

Which is the common program control instructions are. a Branch b. Jump c Call a subroutine d. Return e. Allof these f None of these

Description : Which is the common program control instructions are. a Branch b. Jump c Call a subroutine d. Return e. Allof these f None of these

Last Answer : e. Allof these

Memory access in RISC architecture is limited to instructions a. CALL and RET b. PUSH and POP c. STA and LDA d. MOV and JMP

Description : Memory access in RISC architecture is limited to instructions a. CALL and RET b. PUSH and POP c. STA and LDA d. MOV and JMP

Last Answer : c. STA and LDA

When a subroutine is called, the address of the instruction following the CALL instructions stored in/on the a. stack pointer b. accumulator c. program counter d. stack

Description : When a subroutine is called, the address of the instruction following the CALL instructions stored in/on the a. stack pointer b. accumulator c. program counter d. stack

Last Answer : d. stack

Which of the following instruction is of logical instructions? i) CPL A ii) JC rel iii) DA A iv) ANL A, Rn v) RR A vi) CPL bit a) i, v b) v, iii, I c) iv, ii d) v, iii, ii

Description : Which of the following instruction is of logical instructions? i) CPL A ii) JC rel iii) DA A iv) ANL A, Rn v) RR A vi) CPL bit a) i, v b) v, iii, I c) iv, ii d) v, iii, ii

Last Answer : c) iv, i

Identify direct addressing instructions from following instructions : (i) MOV RO, R5 (ii) MOV RO, 80 H (iii) MOV RO, #75H (iv) ADD A, 45 H

Description : Identify direct addressing instructions from following instructions : (i) MOV RO, R5 (ii) MOV RO, 80 H (iii) MOV RO, #75H (iv) ADD A, 45 H

Last Answer : Instructions ii) and iv) are direct addressing as 80H and 45H are direct addresses

Define stack and explain stack related instructions

Description : Define stack and explain stack related instructions

Last Answer : The stack is a group of memory locations in the R/W memory thatis used for the temporary storage of binary information during the execution of the program. The stack related instructions are PUSH & POP

Explain LDA, STA and DAA instructions

Description : Explain LDA, STA and DAA instructions

Last Answer : LDA copies the data byte into accumulator from the memory location specified by the 16-bit address. STA copies the data byte from theaccumulator in the memory location specified by 16-bit address. DAA changes the contents of the accumulator from binary to 4-bit BCD digits.

Explain the purpose of the I/O instructions IN and OUT.

Description : Explain the purpose of the I/O instructions IN and OUT.

Last Answer : The IN instruction is used to move data from an I/O port into the accumulator. The OUT instruction is used to move data from the accumulator to an I/O port. The IN & OUT instructions are used only on microprocessor, which use a separate address space for interfacing.

State significance of earthing. Draw and explain pipe earthing. State the values of earth resistances for : (i) Substation (ii) Residential wiring (iii) H.T. Line (iv) L.T. Line

Description : State significance of earthing. Draw and explain pipe earthing. State the values of earth resistances for : (i) Substation (ii) Residential wiring (iii) H.T. Line (iv) L.T. Line

Last Answer : Significance of earthing:  * Earthing means connecting the body of the electrical equipment (it means the part which does not carries current under normal condition) to the earth. For example electrical equipment' ... surrounded by charcoal and salt.  the values of earth resistances for: