Microcontroller instruction set

MICROCONTROLLER INSTRUCTION SET

Subject: MICROCONTROLLER AND EMBEDED SYSTEMClass: 5th sem, ECE

PRESENTED BY Jotiram G.Kamble

I/C HOD, SPA ATPADI. Mobile No.: 9561976302

Shivaji Polytechnic Atpadi

Introduction

An instruction is an order or command given to a processor by a computer program. All commands are known as instruction set and set of instructions is known as program.

8051 have in total 111 instructions, i.e. 111 different words available for program writing.


Instruction Format

Where first part describes WHAT should be done, while other explains HOW to do it.

The latter part can be a data (binary number) or the address at which the data is stored.

Depending upon the number of bytes required to represent 1 instruction completely.


Types Of Instructions

Instructions are divided into 3 types;

1. One/single byte instruction.

2. Two/double byte instruction.

3. Three/triple byte instruction.



1. One/single byte instructions :

If operand is not given in the instruction or there is no digits present with instruction, the instructions can be completely represented in one byte opcode.

OPCODE 8 bit



2. Two/double byte instruction:

If 8 bit number is given as operand in the instruction, the such instructions can be completed represented in two bytes.

First byte OPCODE Second byte 8 bit data or I/O port



3. Three/triple byte instruction:

If 16 bit number is given as operand in the instructions than such instructions can be completely represented in three bytes 16 bit number specified may be data or address.



1. First byte will be instruction code.

2. Second byte will be 8 LSB’s of 16 bit number.

3. Third byte will be 8 MSB’s of 16 bit number.

First byte OPCODE. Second byte 8 LSB’s of data/address. Third byte 8 MSB’S of data/address.


Addressing Modes

Addressing modes specifies where the data (operand) is. They specify the source or destination of data (operand) in several different ways, depending upon the situation.

Addressing modes are used to know where the operand located is.


Addressing Modes

There are 6 types of addressing modes:

1. Register addressing.

2. Direct addressing.

3. Register indirect addressing.

4. Immediate addressing.

5. Index addressing.

6. Register specific addressing modeShivaji Polytechnic Atpadi

Register Addressing Mode

In register addressing mode; the source and/or destination is a register.

In this case; data is placed in any of the 8 registers(R0-R7); in instructions it is specified with letter Rn (where N indicates 0 to 7).


Register Addressing Mode

For example;

1. ADD A, Rn (This is general instruction).

2. ADD A, R5 (This instruction will add the contents of register R5 with the accumulator contents).


Direct Addressing Mode

In direct addressing mode; the address of memory location containing data to be read is specified in instruction.

In this case; address of the data is given with the instruction itself.


Direct Addressing Mode

For example;

1. MOV A, 25H (This instruction will read/move the data from internal RAM address 25H and store it in the accumulator.


Register Indirect Addressing Mode

In register indirect addressing mode; the contents of the designated register are used as a pointer to memory.

In this case; data is placed in memory, but address of memory location is not given directly with instruction.


Register Indirect Addressing Mode

For example;

1. MOV A,@R0 This instruction moves the data from the register whose address is in the R0 register into the accumulator.


Immediate Addressing Mode

In immediate addressing mode, the data is given with the instruction itself.

In this case; the data to be stored in memory immediately follows the opcode.


Immediate Addressing Mode

For example;

1. MOV A, #25H (This instruction will move the data 25H to accumulator.


Index Addressing Mode

Offset (from accumulator) is added to the base index register( DPTR OR Program Counter) to form the effective address of the memory location.

In this case; this mode is made for reading tables in the program memory.


Index Addressing Mode

For example;

1. MOVC A, @ A + DPTR ( This instruction moves the data from the memory to accumulator; whose address is computed by adding the contents of accumulator and DPTR)



1. Data transfer instructions.

2. Arithmetic instructions.

3. Logical instructions.

4. Logical instructions with bits.

5. Branch instructions.


Data Transfer Instructions

These instructions move the content of one register to another one.

Data can be transferred to stack with the help of PUSH and POP instructions.



MNEMONIC :- MOV A, Rn Operation :- (A) (Rn) Description :- This instruction will copy the

content of the register Rn to the register A.

Addressing mode:- Register addressing mode Byte:- 1 byte Example :- MOV A,R1

1




MNEMONIC :- MOV A, direct Operation :- (A) (direct) Description :- This instruction will copy the

content of direct address given in instruction to the register A.

Addressing mode:- Direct addressing mode Byte:- 2 byte Example :- MOV A,40H

2


MNEMONIC :- MOV A, @Ri Operation :- (A) (@Ri) Description :- This instruction will copy the

content of memory location whose address is given in register Ri of selected register bank to the register A.

Addressing mode:- Indirect addressing mode Byte:- 1 byte Example :- MOV A,@R0


3


MNEMONIC :- MOV A,#data Operation :- (A) (data) Description :- This instruction will copy the

immediate data to the register A. Addressing mode:- Immediate addressing

mode Byte:- 2 byte Example :- MOV A,#30H


4


MNEMONIC :- MOV Rn, A Operation :- (Rn) (A) Description :- This instruction will copy the

content of accumulator to the register Rn of selected register bank.

Addressing mode:- Register addressing mode Byte:- 1 byte Example :- MOV R0,A


5


MNEMONIC :- MOV Rn, direct Operation :- (Rn) (direct) Description :- This instruction will copy the

content of direct location whose address specified in the instruction to the register Rn of selected register bank.

Addressing mode:- Direct addressing mode Byte:- 2 byte Example :- MOV R5,30H


6


MNEMONIC :- MOV Rn, #data Operation :- (Rn) (data) Description :- This instruction will copy the

immediate data to the register Rn of selected register bank.

Addressing mode:- Immediate addressing mode

Byte:- 2 byte Example :- MOV R5,#20H


7


MNEMONIC :- MOV direct, A Operation :- (direct) (A) Description :- This instruction will copy the

Accumulator to the direct address specified in instruction.

Addressing mode:- Direct addressing mode Byte:- 2 byte Example :- MOV 20H,A


8


MNEMONIC :- MOV direct, Rn Operation :- (direct) (Rn) Description :- This instruction will copy the

Accumulator to the register Rn in selected register bank.

Addressing mode:- Direct addressing mode Byte:- 2 byte Example :- MOV 20H,R5


9


MNEMONIC :- MOV direct, direct Operation :- (direct) (direct) Description :- This instruction will copy the

content of source direct address to destination address.

Addressing mode:- Direct addressing mode Byte:- 3 byte Example :- MOV 20H,30H


10


MNEMONIC :- MOV direct, @Ri Operation :- (direct) (@Ri) Description :- This instruction will copy the

content of memory location whose address is specified in register Ri of selected register bank to direct address in the instruction.

Addressing mode:- Indirect addressing mode Byte:- 2 byte Example :- MOV 50H,@R7


11


MNEMONIC :- MOV direct, #data Operation :- (direct) (data) Description :- This instruction will copy the

immediate data to direct address specified in the instruction.


Byte:- 3 byte Example :- MOV 50H,#25H


12


MNEMONIC :- MOV @Ri, A Operation :- (@Ri) (A) Description :- This instruction will copy the

content of accumulator to the memory location whose direct address specified in Ri of selected register bank.

Addressing mode:- Indirect addressing mode Byte:- 1 byte Example :- MOV @R3,A


13


MNEMONIC :- MOV @Ri, direct Operation :- (@Ri) (direct) Description :- This instruction will copy the

content of direct address specified in instruction to the memory location pointed by Ri of selected register bank.

Addressing mode:- direct addressing mode Byte:- 2 byte Example :- MOV @R4,55H


14


MNEMONIC :- MOV @Ri, #data Operation :- (@Ri) (data) Description :- This instruction will copy the

immediate data to the memory location pointed by Ri of selected register bank.

Addressing mode:- immediate addressing mode

Byte:- 2 byte Example :- MOV @R4,#55H


15


16 MNEMONIC :- MOV DPTR,#data16 Operation :- (DPH) (#data15-8)

(DPL) (#data7-0) Description :- This instruction will copy the

immediate 16bit data to the data pointer. Addressing mode:- Immediate addressing

mode Byte:- 3 byte Example :- MOV DPTR,#5456H



17 MNEMONIC :- MOVC A, @A+DPTR Operation :- (A) (A)+(DPTR) Description :- This instruction will copy the

content of memory location whose address is specified in accumulator with data pointer to the Accumulator.

Addressing mode:- Indirect addressing mode Byte:- 1 byte Example :- MOVCA,@A+DPTR



MNEMONIC :- MOVC A, @A+PC Operation :- (A) (A)+(PC) Description :- This instruction will copy the

content of memory location whose address is specified in accumulator with program counter to the Accumulator.

Addressing mode:- Indirect addressing mode Byte:- 1 byte Example :- MOVCA,@A+PC

18




MNEMONIC :- MOVX A, @Ri Operation :- (A) (@Ri) Description :- This instruction will copy the

content of external memory location whose address is specified in Ri of selected register bank to the Accumulator.

Addressing mode:- Indirect addressing mode Byte:- 1 byte Example :- MOVX A, @R1

19


MNEMONIC :- MOVX A, @DPTR Operation :- (A) (@DPTR) Description :- This instruction will copy the

content of external memory location whose address is specified in data pointer to the Accumulator.

Addressing mode:- Indirect addressing mode Byte:- 1 byte Example :- MOVX A, @DPTR

20



MNEMONIC :- MOVX @Ri, A Operation :- (@Ri) (A) Description :- This instruction will copy the

content of accumulator to the external memory location whose address is specified in Ri of selected register bank.

Addressing mode:- Indirect addressing mode Byte:- 1 byte Example :- MOVX @Ri, A

21



MNEMONIC :- MOVX @DPTR,A Operation :- (@DPTR) (A) Description :- This instruction will copy the

content of accumulator to the memory location whose address is specified in DPTR.

Addressing mode:- Indirect addressing mode Byte:- 1 byte Example :- MOVX @DPTR,A

22



MNEMONIC :- PUSH direct Operation :- (SP) (SP+1) Description :- This instruction will increment

the content of direct byte by 1 and copy to stack pointer.

Addressing mode:- Direct addressing mode Byte:- 2 byte Example :- PUSH DPL

PUSH DPH

23



MNEMONIC :- POP direct Operation :- (SP) (SP-1) Description :- This instruction will decrement

the content of direct byte by 1 and copy to stack pointer.

Addressing mode:- Direct addressing mode Byte:- 2 byte Example :- POP DPL

POP DPH

24



MNEMONIC :- XCH A, Rn Operation :- (A) (Rn) Description :- This instruction will exchange

the content of accumulator with the content of register Rn of selected register bank.

Addressing mode:- register addressing mode Byte:- 1 byte Example :- XCH A, R5

25



MNEMONIC :- XCH A, direct Operation :- (A) (direct) Description :- This instruction will exchange

the content of accumulator with the content of direct address.

Addressing mode:- direct addressing mode Byte:- 2 byte Example :- XCH A,10H

26



MNEMONIC :- XCH A, @Ri Operation :- (A) (@Ri) Description :- This instruction will exchange

the content of accumulator with the content of memory location whose address is specified in register Ri of selected register bank.

Addressing mode:- Indirect addressing mode Byte:- 1 byte Example :- XCH A,@R1

27



MNEMONIC :- XCHD A, @Ri Operation :- (A(3-0)) (@Ri(3-0)) Description :- This instruction will exchange

the lower nibble of accumulator with the lower nibble of memory location whose address is specified in register Ri of selected register bank.

Addressing mode:- Indirect addressing mode Byte:- 1 byte Example :- XCHD A,@R5

28


Arithmetic Instructions

These instructions perform several basic operations. After execution, the result is stored in the first operand.

8 bit addition, subtraction, multiplication, increment-decrement instructions can be performed.



MNEMONIC :- ADD A, Rn Operation :- (A) = (A)+(Rn) Description :- This instruction will add the

content of accumulator to the content of register Rn of selected register bank. The result is stored in A register.

Addressing mode:- Register addressing mode Byte:- 1 byte Example :- ADD A,R0


29


MNEMONIC :- ADD A, direct Operation :- (A) = (A)+(direct) Description :- This instruction will add the

content of accumulator to the content of memory location whose address specified in instruction. The result is stored in A register.

Addressing mode:- direct addressing mode Byte:- 2 byte Example :- ADD A,30H


30


MNEMONIC :- ADD A, @Ri Operation :- (A) = (A)+(@Ri) Description :- This instruction will add the

content of accumulator to the content of memory location whose address specified in Ri of selected register bank. The result is stored in A register.

Addressing mode:- indirect addressing mode Byte:- 1 byte Example :- ADD A,@R2


31


MNEMONIC :- ADD A, #data Operation :- (A) = (A)+(#data) Description :- This instruction will add the

content of accumulator to the immediate data. The result is stored in A register.


Byte:- 2 byte Example :- ADD A,#56H


32


MNEMONIC :- ADDC A, Rn Operation :- (A) = (A)+(Rn)+(C) Description :- This instruction will add the

content of accumulator to the content of register Rn with carry flag. The result is stored in A register.

Addressing mode:- register addressing mode Byte:- 1 byte Example :- ADD A,R5


33


MNEMONIC :- ADDC A, direct Operation :- (A) = (A)+(direct)+(C) Description :- This instruction will add the

content of accumulator to the content of memory location whose address is specified in instruction with carry flag. The result is stored in A register.

Addressing mode:- direct addressing mode Byte:- 2 byte Example :- ADD A,30H


34


MNEMONIC :- ADDC A, #data Operation :- (A) = (A)+(#data)+(C) Description :- This instruction will add the

content of accumulator to the immediate data with carry flag. The result is stored in A register.


Byte:- 2 byte Example :- ADDC A,#30H


35


MNEMONIC :- ADDC A, @Ri Operation :- (A) = (A)+(@Ri)+(C) Description :- This instruction will add the

content of accumulator to the content of memory location whose address is specified in Ri of selected register bank with carry. The result is stored in A register.

Addressing mode:- indirect addressing mode Byte:- 1 byte Example :- ADDC A,@R7


36


MNEMONIC :- SUBB A, Rn Operation :- (A) = (A)-(Rn)-(C) Description :- This instruction will subtract the

content of register Rn with carry from the accumulator. The result is stored in A register.

Addressing mode:- Register addressing mode Byte:- 1 byte Example :- SUBB A,R7


37


MNEMONIC :- SUBB A, #data Operation :- (A) = (A)-(#data)-(C) Description :- This instruction will subtract the

content of accumulator to the immediate data with carry. The result is stored in A register.


Byte:- 2 byte Example :- SUBB A,#34H


38


MNEMONIC :- SUBB A, direct Operation :- (A) = (A)-(direct)-(C) Description :- This instruction will subtract the

content of accumulator to the content of memory location whose address is specified in instruction with carry. The result is stored in A register.

Addressing mode:- Direct addressing mode Byte:- 2 byte Example :- SUBB A,50H


39


MNEMONIC :- SUBB A, @Ri Operation :- (A) = (A)-(@Ri)-(C) Description :- This instruction will subtract the

content of accumulator to the content of memory location whose address is specified in register Ri with carry. The result is stored in A register.

Addressing mode:- Indirect addressing mode Byte:- 1 byte Example SUBB A,@R4


40


MNEMONIC :- INC A Operation :- (A) = (A)+1 Description :- This instruction will increment

the content of accumulator by 1 and store in accumulator.

Addressing mode:- Register addressing mode Byte:- 1 byte Example :- INC A

41



MNEMONIC :- INC Rn Operation :- (Rn) = (Rn)+1 Description :- This instruction will increment

the content of register Rn of selected register bank by 1 and store in that register.

Addressing mode:- Register addressing mode Byte:- 1 byte Example :- INC R5

42



MNEMONIC :- INC direct Operation :- (direct) = (direct)+1 Description :- This instruction will increment

the content of memory location whose address is in instruction by 1 and store in that memory location.

Addressing mode:- Direct addressing mode Byte:- 2 byte Example :- INC 30H

43



MNEMONIC :- INC @Ri Operation :- (@Ri) = (@Ri)+1 Description :- This instruction will increment

the content of memory location whose address is in Ri for selected register bank by 1 and store in that memory location.

Addressing mode:- Indirect addressing mode Byte:- 1 byte Example :- INC @R5

44



MNEMONIC :- INC DPTR Operation :- (DPTR) = (DPTR)+1 Description :- This instruction will increment

the content of data pointer by 1 and store in data pointer.

Addressing mode:- register addressing mode Byte:- 1 byte Example :- INC DPTR

45



MNEMONIC :- DEC A Operation :- (A) = (A)-1 Description :- This instruction will decrement

the content of accumulator by 1 and store in accumulator.

Addressing mode:- Register addressing mode Byte:- 1 byte Example :- DEC A

46



MNEMONIC :- DEC Rn Operation :- (Rn) = (Rn)-1 Description :- This instruction will decrement

the content of register Rn of selected register bank by 1 and store in that register.

Addressing mode:- Register addressing mode Byte:- 1 byte Example :- DEC R5

47



MNEMONIC :- DEC direct Operation :- (direct) = (direct)-1 Description :- This instruction will decrement

the content of memory location whose address is in instruction by 1 and store in that memory location.

Addressing mode:- Direct addressing mode Byte:- 2 byte Example :- DEC 30H

48



MNEMONIC :- DEC @Ri Operation :- (@Ri) = (@Ri)-1 Description :- This instruction will decrement

the content of memory location whose address is in Ri for selected register bank by 1 and store in that memory location.

Addressing mode:- Indirect addressing mode Byte:- 1 byte Example :- DEC @R5

49



MNEMONIC :- MUL AB Operation :- (A7-0)& (B15-8) = (A)x(B) Description :- This instruction will multiplies

the content of accumulator and B register. The low order byte result is stored in A reg. and higher order byte store in B register.

Addressing mode:- register addressing mode Byte:- 1 byte Example :- MUL AB

50



51


MNEMONIC :- DIV AB Operation :- (A7-0)-quotient

(B15-8) reminder =(A)/(B) Description :- This instruction will divides the

content of accumulator and B register. The quotient is stored in A register and reminder is stored in B register.

Addressing mode:- register addressing mode Byte:- 1 byte Example :- DIV AB


MNEMONIC :- DA A Operation :- decimal adjust accumulator Description :- This instruction will adjust the

sum of two packed BCD numbers to an eight bit value.

Addressing mode:- register specific addressing mode

Byte:- 1 byte Example :- if A=56 and B=67 cy=1 then BCD add

is BEH and is a unpacked no. then adjust the decimal means add 66 on that no the result is 24H

52


Logical Instructions

These instructions perform logical operations between two register contents on bit by bit basis.

After execution, the result is stored in the first operand.




MNEMONIC :- ANL A, Rn Operation :- (A) = (A)^(Rn) Description :- This instruction will perform

bitwise logical AND operation between the content of A register and Register Rn of selected register bank. The result will be stored in A register.

Addressing mode:- Register addressing mode Byte:- 1 byte Example :- ANL A,R3

53



MNEMONIC :- ANL A, direct Operation :- (A) = (A)^(direct) Description :- This instruction will perform

bitwise logical AND operation between the content of A register and content of memory location whose address is specified in instruction. The result will be stored in A register.

Addressing mode:- direct addressing mode Byte:- 2 byte Example :- ANL A,85H

54



MNEMONIC :- ANL A, @Ri Operation :- (A) = (A)^(@Ri) Description :- This instruction will perform

bitwise logical AND operation between the content of A register and content of memory location whose address is specified in Ri of selected register bank. The result will be stored in A register.

Addressing mode:- Indirect addressing mode Byte:- 1 byte Example :- ANL A,@R1

55



MNEMONIC :- ANL A, #data Operation :- (A) = (A)^(data) Description :- This instruction will perform

bitwise logical AND operation between the content of A register and content of immediate data. The result will be stored in A register.


Byte:- 2 byte Example :- ANL A,#43H

56



MNEMONIC :- ANL direct, A Operation :- (direct) = (direct)^(A) Description :- This instruction will perform

bitwise logical AND operation between the content of Accumulator and content of memory location whose address is specified in instruction. The result will be stored in that memory location.

Addressing mode:- direct addressing mode

Byte:- 2 byte Example :- ANL 43H,A

57



MNEMONIC :- ANL direct, #data Operation :- (direct) = (direct)^(data) Description :- This instruction will perform

bitwise logical AND operation between the content of immediate data and content of memory location whose address is specified in instruction. The result will be stored in that memory location.


Byte:- 3 byte Example :- ANL 43H,#23H

58



MNEMONIC :- ORL A, Rn Operation :- (A) = (A) +(Rn) Description :- This instruction will perform

bitwise logical OR operation between the content of accumulator and content of register Rn. The result will be stored in accumulator.

Addressing mode:- Register addressing mode

Byte:- 1 byte Example :- ORL A,R4

59


MNEMONIC :- ORL A, #data Operation :- (A) = (A) +(data) Description :- This instruction will perform

bitwise logical OR operation between the immediate data and content of accumulator. The result will be stored in accumulator.


Byte:- 2 byte Example :- ORL A,#45H

60



MNEMONIC :- ORL A, direct Operation :- (A) = (A) +(direct) Description :- This instruction will perform

bitwise logical OR operation between the content of accumulator and content of memory location whose address is specified in instruction. The result will be stored in accumulator.

Addressing mode:- Direct addressing mode

Byte:- 2 byte Example :- ORL A,56H

61



MNEMONIC :- ORL A, @Ri Operation :- (A) = (A) +(@Ri) Description :- This instruction will perform

bitwise logical OR operation between the content of accumulator and content of memory location whose address is specified in Ri. The result will be stored in accumulator.

Addressing mode:- indirect addressing mode

Byte:- 1 byte Example :- ORL A,@R3

62



MNEMONIC :- ORL direct, A Operation :- (direct) = (direct) +(A) Description :- This instruction will perform

bitwise logical OR operation between the content of accumulator and content of memory location whose address is specified in instruction. The result will be stored in that location .


Byte:- 2 byte Example :- ORL 25H,A

63



MNEMONIC :- ORL direct, #data Operation :- (direct) = (direct) +(data) Description :- This instruction will perform

bitwise logical OR operation between the immediate data and content of memory location whose address is specified in instruction. The result will be stored in that location .


Byte:- 3 byte Example :- ORL 25H,#32H

64



MNEMONIC :- XRL A, Rn Operation :- (A) = (A) (Rn) Description :- This instruction will perform

bitwise logical EX OR operation between the content of accumulator and content of register Rn. The result will be accumulator.

Addressing mode:- register addressing mode

Byte:- 1 byte Example :- XRL A,R0

65



MNEMONIC :- XRL A, direct Operation :- (A) = (A) (direct) Description :- This instruction will perform

bitwise logical EX OR operation between the content of accumulator and content of memory location whose address is specified in instruction. The result will be accumulator.

Addressing mode:- Direct addressing mode

Byte:- 2 byte Example :- XRL A,30H

66



MNEMONIC :- XRL A, @Ri Operation :- (A) = (A) (@Ri) Description :- This instruction will perform

bitwise logical EX OR operation between the content of accumulator and content of memory location whose address is specified in Ri. The result will be accumulator.

Addressing mode:- indirect addressing mode

Byte:- 1 byte Example :- XRL A,@R4

67



MNEMONIC :- XRL A, #data Operation :- (A) = (A) (data) Description :- This instruction will perform

bitwise logical EX OR operation between the content of accumulator and content of immediate data. The result will be accumulator.


Byte:- 2 byte Example :- XRL A,#25H

68



MNEMONIC :- XRL direct, #data Operation :- (direct) = (direct) (data) Description :- This instruction will perform

bitwise logical EX OR operation between the content of memory location whose address is specified in instruction and content of immediate data. The result will be stored in that location.


Byte:- 3 byte Example :- XRL 45H,#25H

69



MNEMONIC :- XRL direct, A Operation :- (direct) = (direct) (A) Description :- This instruction will perform

bitwise logical EX OR operation between the content of memory location whose address is specified in instruction and content of accumulator. The result will be stored in that location.


Byte:- 2 byte Example :- XRL 45H,A

70



MNEMONIC :- CLR A Operation :- A=0 Description :- This instruction will clear all the

bits of accumulator to zero. Addressing mode:- register specific

addressing mode Byte:- 1 byte Example :- CLR A

71



MNEMONIC :- CPL A Operation :- A=A Description :- This instruction will

complement all the bits of accumulator. Addressing mode:- register specific

addressing mode Byte:- 1 byte Example :- CPL A

72



MNEMONIC :- SWAP A Operation :- A3-0=A7-4

Description :- This instruction will interchange the lower order byte and higher order byte of the accumulator.


Byte:- 1 byte Example :- SWAP A

73



MNEMONIC :- RL A Operation :- rotate accumulator left Description :- This instruction will rotate the

content of accumulator by one bit to the left. Addressing mode:- register specific

addressing mode Byte:- 1 byte Example :- RL A

74



MNEMONIC :- RR A Operation :- Rotate accumulator right Description :- This instruction will rotate the

content of accumulator by one bit to the right. Addressing mode:- register specific

addressing mode Byte:- 1 byte Example :- RR A

75



MNEMONIC :- RLC A Operation :-Rotate accumulator left with carry Description :- This instruction will rotate the

eight bits in the accumulator and carry by one bit to the left.


Byte:- 1 byte Example :- RLC A

76



MNEMONIC :- RRC A Operation :-Rotate accumulator right with carry Description :- This instruction will rotate the

eight bits in the accumulator and carry by one bit to the right.


Byte:- 1 byte Example :- RRC A

77

Logical Instructions On Bits

Similar to logical instructions, these instructions also perform logical operations.

The difference is that these operations are performed on single bits.



MNEMONIC :- CLR bit Operation :- (bit) = 0 Description :- This instruction will clear the

indicated bit. Addressing mode:- register and direct

addressing mode Byte:- 1 byte Example :- CLR P1.0


78



MNEMONIC :- CPL bit Operation :- (bit) = (bit) Description :- This instruction will

complement the indicated bit. Addressing mode:- register and direct

addressing mode Byte:- 1 byte Example :- CPL P1.0

79



MNEMONIC :- SETB bit Operation :- (bit) = 1 Description :- This instruction will set the

indicated bit. Addressing mode:- register and direct

addressing mode Byte:- 1 byte Example :- SETB P1.5

80



MNEMONIC :- ANL C,bit Operation :- (C) = (C)^(bit) Description :- This instruction will logically

AND the specified bit with carry bit. Addressing mode:- direct addressing mode Byte:- 2 byte Example :- ANL C, P1.0

81


MNEMONIC :- ANL C,/bit Operation :- (C) = (C)+(bit) Description :- This instruction will logically

AND the complement of specified bit with carry bit. Addressing mode:- direct addressing mode Byte:- 1 byte Example :- ORL C, /P1.0

82




MNEMONIC :- ORL C,bit Operation :- (C) = (C)+(bit) Description :- This instruction will logically OR

the specified bit with carry bit. Addressing mode:- direct addressing mode Byte:- 2 byte Example :- ORL C, P1.0

83


MNEMONIC :- ORL C,/bit Operation :- (C) = (C)+(bit) Description :- This instruction will logically OR

the complement of specified bit with carry bit. Addressing mode:- direct addressing mode Byte:- 2 byte Example :- ORL C, /P1.0

84




MNEMONIC :- MOV bit, C Operation :- (bit) = (C) Description :- This instruction will copy the

carry flag into specified bit in the instruction. Addressing mode:- direct addressing mode Byte:- 2 byte Example :- MOV P1.0,C

85



MNEMONIC :- MOV C, bit Operation :- (C) = (bit) Description :- This instruction will copy the

specified bit in the instruction to the carry flag. Addressing mode:- direct addressing mode Byte:- 2 byte Example :- MOV C, P1.0

86



MNEMONIC :- SETB C Operation :- (C) = 1 Description :- This instruction will set the

carry bit. Addressing mode:- register addressing mode Byte:- 1 byte Example :- SETB C

87



MNEMONIC :- CLR C Operation :- (C) = 0 Description :- This instruction will clear the

carry bit. Addressing mode:- register addressing mode Byte:- 1 byte Example :- CLR C

88



MNEMONIC :- CPL C Operation :- (C) = (C) Description :- This instruction will

complement the carry bit. Addressing mode:- register addressing mode Byte:- 1 byte Example :- CPL C

89



MNEMONIC :- JC rel Operation :- jump if carry is set

(PC)=(PC)+2, if c=1 then PC=PC+rel

Description :- This instruction will jump the address indicated if carry is set otherwise it will continue with next instruction.


Byte:- 2 byte Example :- JC L1

90



MNEMONIC :- JNC rel Operation :- jump if carry not set

(PC)=(PC)+2, if c=0 then PC=PC+rel

Description :- This instruction will jump the address indicated if carry is reset otherwise it will continue with next instruction.


Byte:- 2 byte Example :- JNC L1

91



MNEMONIC :- JB bit, rel Operation :- jump if bit is set

(PC)=(PC)+3, if bit=1 then PC=PC+rel

Description :- This instruction will jump the address indicated if bit is set otherwise it will continue with next instruction.


Byte:- 3 byte Example :- JB P2.1,L1

92


MNEMONIC :- JNB bit, rel Operation :- jump if bit is not set

(PC)=(PC)+3, if bit=0 then PC=PC+rel

Description :- This instruction will jump the address indicated if bit is reset otherwise it will continue with next instruction.


Byte:- 3 byte Example :- JNB P2.1,L1


93


MNEMONIC :- JBC bit, rel Operation :- jump if bit is set and clear bit

(PC)=(PC)+3, if bit=1 then bit=0, PC=PC+rel

Description :- This instruction will jump the address indicated if bit is set otherwise it will continue with next instruction. And bit is cleared.


Byte:- 3 byte Example :- JBC P2.1,L1


94

In this group, instructions are related to the flow of the program, these are used to control the operation like, JUMP and CALL instructions.

Some instructions are used to introduce delay in the program, to the halt program.


Program Flow Control Instructions and Branch Instructions


MNEMONIC :- ACALL adr11Operation :- (PC) = (PC) + 2 (SP) = (SP) + 1 ((SP)) = (PC7 – 0) (SP) = (SP) + 1 ((SP)) = (PC15-8)

(PC10-0)=page address

Description :- This instruction unconditionally call routine at the address indicated. At the end of subroutine the program will resume operation at the opcode address following the call instruction. The return address of the next inst. After the call instruction is in the program counter.


Byte:- 2 byte Example :- ACALL 0237H

95



MNEMONIC :- LCALL adr16Operation :- (PC) = (PC) + 3 (SP) = (SP) + 1 ((SP)) = (PC7 – 0) (SP) = (SP) + 1 ((SP)) = (PC15-8)

Description :- This instruction unconditionally call subroutine that is located at the indicated address.


Byte:- 3 byte Example :- LCALL 8000H

96



MNEMONIC :- AJMP adr11Operation :- (PC) = (PC) + 2 (PC10-0)=page addressDescription :- This instruction will absolute

jump for indicated address.


Byte:- 2 byte Example :- AJMP L1/5400H address

97



MNEMONIC :- LJMP adr16Operation :- (PC15-0)=page address

Description :- This instruction will long jump for indicated address.


Byte:- 3 byte Example :- AJMP L1/5400H address

98



MNEMONIC :- SJMP relOperation :- (PC)=(PC)+2

(PC)=(PC)+relDescription :- This instruction will short jump

for indicated address.it may be one or two instructions.


Byte:- 2 byte Example :- SJMP L1

99



MNEMONIC :- JMP @A+DPTROperation :- (PC)=(A)+(DPTR)

(PC)=(PC)+relDescription :- This instruction will add the

content of accumulator and data pointer and jump for that indirect address.

Addressing mode:- indirect addressing mode Byte:- 1 byte Example :- JMP @A+DPTR

100



MNEMONIC :- JZ rel Operation :- jump if accumulator is zero

(PC)=(PC)+2, if A=0 then PC=PC+rel

Description :- This instruction will jump to the address indicated if all the bits of accumulator are zero otherwise it will continue with next instruction.


Byte:- 2 byte Example :- JZ LEBEL5

101



MNEMONIC :- JNZ rel Operation :- jump if accumulator is not zero

(PC)=(PC)+2, if A=1 then PC=PC+rel

Description :-This instruction will jump to the address indicated if all the bits of accumulator are not zero otherwise it will continue with next instruction.


Byte:- 2 byte Example :- JNZ L5

102



MNEMONIC :- CJNE a,direct,relOperation :- (PC)=(PC)+3 if A>direct then

(PC)=(PC)+rel. if A<direct then C=1 else C=0.Description :- This instruction will compare the

content of accumulator and the content of memory location whose address is in instruction and jump to indicated address.


Byte:- 3 byte Example :- CJNE A,60H, L1

103



MNEMONIC :- CJNE a,#data,relOperation :- (PC)=(PC)+3 if A>data then

(PC)=(PC)+rel. if A<data then C=1 else C=0.Description :- This instruction will compare the

content of accumulator and the content of immediate data and jump to indicated address.


Byte:- 3 byte Example :- CJNE A,#60H, L1

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MNEMONIC :- CJNE Rn,#data,relOperation :- (PC)=(PC)+3 if Rn>data then

(PC)=(PC)+rel. if Rn<data then C=1 else C=0.Description :- This instruction will compare the

content of register Rn of selected register bank and the content of immediate data and jump to indicated address.


Byte:- 3 byte Example :- CJNE Rn,#60H, L1

105



MNEMONIC :- CJNE @Ri,#data,relOperation :- (PC)=(PC)+3 if @Ri>data then

(PC)=(PC)+rel. if @Ri<data then C=1 else C=0.Description :- This instruction will compare the

content of memory location whose address is specified in register Ri of selected register bank and the content of immediate data and jump to indicated address.


Byte:- 3 byte Example :- CJNE @R5,#60H, L1

106



MNEMONIC :- DJNZ Rn,relOperation :- (PC)=(PC)+2 if Rn-1 and if Rn<>0

then (PC)=(PC)+rel. Description :- This instruction will decrement the

content of register Rn of selected register bank and and jump if not zero to indicated address.


Byte:- 2 byte Example :- DJNZ R5,#60H, L1

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MNEMONIC :- NOPOperation :- no operationDescription :- This instruction will perform no

operation . Addressing mode:- register specific addressing mode

Byte:- 1 byte Example :- NOP


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MNEMONIC :- RETOperation :- (PC15-8) ((SP)) (SP) (SP) – 1 (PC7-0) ((SP)) (SP) (SP) - 1Description :- when instruction is executed the uc

return back to the program from where subroutine was called.


Byte:- 1 byte Example :- RET address

109



MNEMONIC :- RETIOperation :- (PC15-8) ((SP)) (SP) (SP) – 1 (PC7-0) ((SP)) (SP) (SP) – 1Description :- when instruction is executed the uc

return from the ISR routine to the program from where subroutine was called.


Byte:- 1 byte Example :- RETI address

110



MNEMONIC :- DJNZ direct,relOperation :- (PC)=(PC)+2 if Rn-1 and if Rn<>0

then (PC)=(PC)+rel. Description :- This instruction will decrement the

content of memory location whose address is specified in instruction and jump if not zero to indicated address.


Byte:- 3 byte Example :- DJNZ 60H, L1

111


Summary

Instruction set. Addressing modes. Data transfer instruction. Arithmetic instruction. Logical instruction. Logical operation on bits. Program and branch instructions


Microcontroller instruction set

Engineering

Transcript of Microcontroller instruction set