ATPL00B datasheet(33/152 Pages) ATMEL

33 / 152 page

Atmel ATPL00B [datasheet]

43028A-ATPL - 9/12

4.4.5

Data Transfer Instructions

Internal RAM

Table 4-5 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. All of these instructions are executed in 1 mc.

Table 4-5.

Data Transfer Instructions that Access Internal Data Memory Space

MNEMONIC

OPERATION

ADDRESSING MODES

EXE

CUTI

DIR

IND

REG

IMM

TIME

(mc)

MOV A,<src>

A = <src>

MOV <dest>,A

<dest> = A

MOV <dest>,<src>

MOV DPTR,#data16

DPTR = 16-bit immediate constant

PUSH <src>

INC SP:MOV“@SP”,<src>

POP <dest>

MOV <dest>,“@SP”:DEC SP

XCH A,<byte>

ACC and <byte> exchange data

XCHD A,@Ri

ACC and @Ri exchange low nibbles

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 IDATA can be accessed only by indirect

addressing, and SFR space only by direct addressing.

Note that in any 80C51 device, the stack resides in on-chip RAM, and grows upwards. The PUSH instruction first

increments the Stack Pointer (SP), then copies the byte into the stack. PUSH and POP use only direct addressing to

identify the byte being saved or restored, but the stack itself is accessed by indirect addressing using the SP register.

This means the stack can go into the Upper 128 bytes of RAM, if they are implemented, but not into SFR space.

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.

The XCH A, <byte> instruction causes the Accumulator and addressed byte to exchange data. The XCHD A, @Ri

instruction is similar, but only the low nibbles are involved in the exchange.

External RAM (from microcontroller point of view)

Table 4-6 shows a list of the Data Transfer instructions that access external Data Memory. Only indirect addressing can

be used. The choice is whether to use a one-byte address, @Ri, where Ri can be either R0 or R1 of the selected

Note that in all external Data RAM accesses, the Accumulator is always either the destination or source of the data.

The read and write strobes to external RAM are activated only during the execution of a MOVX instruction.

ATPL00B Datasheet(PDF) 33 Page - ATMEL Corporation

ATPL00B Datasheet(HTML) 33 Page - ATMEL Corporation

Html Pages

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 ...More

Datasheet Download

Link URL