Tutorial Microcontroller MCS-51 ATMEL ISP

PelatihanMikrokontroller
15 Januari 2011

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Data Transfer

Internal RAM
Table 3 shows the menu of instructions that are available for moving data around within the internal memory spaces, and the addressing modes that can be used with each one. With a 12MHz clock, all of these instructions execute in either 1 or 2ms. The MOV <dest>, <src> instruction allows data to be transferred between any two internal RAM or SFR locations without going through the Accumulator. Remember, the Upper 128 bytes of data RAM can be accessed only by indirect addressing, and SFR space only by direct addressing.The Data Transfer instructions include a 16-bit MOV that can be used to initialize the Data Pointer (DPTR) for look-up tables in Program Memory, or for 16-bit external Data Memory accesses.

Table 1.4.3. MCS-51 Data Transfer Instruction

Mnemonic	Operation	Addressing Mode	Exect.
Dir	Ind	Reg	Imm	Timer uS
Mov A,<src>	A=<src>
Mov <dest>,A	<dest>=A
Mov <dest>, <src>	<dest>=<src>
Mov DPTR,#data16	DPTR=16 bit immediate const	Accumulator Only
Push <src>	Inc SP
Pop <src>	Dec SP	Data Pointer Only
Xch A,<byte>	Acc and <byte> exchange data	Accumulator Only
Xchd A,@Ri	Acc and @Ri exchange low nibbles

;Lesson 1.4.1.

      Org 0hStart:Mov A,#1    ; put 1 into the accumulator      ADD A,#2    ; add the constant 2 to Accumulator (1+2)      Mov 78h,#3  ; put 3 into internal RAM 78h
ADD A, 78h  ; add Acc and RAM 78h content
Mov R0, #79h; put 79 into R0      Mov @R0, #4 ; put 4 into RAM 79h      ADD A,@R0   ; add Acc and RAM 79h content      Mov R5, #5  ; put 5 into R5      ADD A,R5    ; add Acc and R5      end

;Lesson 1.4.2.

      Org 0hStart:Mov 78h,#34h ; [ 78h ] = 34h      Mov 79h,#12h ; [ 79h ] =12h       Mov 7Ah,#0EFh; [ 7Ah ] = EFh      Mov 7Bh,#12h ; [ 7Bh ] = 12h      Mov A,78h    ; A = [ 78h ]       Add A,7Ah    ; A = A + [ 78h ]      Mov 78h,A    ; [ 78h ] = A      Mov A,79h    ; A = [ 79h ]      ADDC A,7Bh   ; A = A + [ 7Bh ] + C       Mov 79h,A     ; [ 79h ] = A      end

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Tutorial Microcontroller MCS-51 ATMEL ISP