ST72E121J4D0 查看數據表（PDF） - STMicroelectronics

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ST72E121J4D0

8-BIT MCU WITH 8 TO 16K OTP/EPROM, 384 TO 512 BYTES RAM, WDG, SCI, SPI AND 2 TIMERS

STMicroelectronics 

ST72E121 ST72T121

5 INSTRUCTION SET

5.1 ST7 ADDRESSING MODES

The ST7 Core features 17 different addressing

modes which can be classified in 7 main groups:

Addressing Mode

Inherent

Immediate

Direct

Indexed

Indirect

Relative

Bit operation

Example

nop

ld A,#$55

ld A,$55

ld A,($55,X)

ld A,([$55],X)

jrne loop

bset byte,#5

The ST7 Instruction set is designed to minimize

the number of bytes required per instruction: To do

so, most of the addressing modes may be subdi-

vided in two sub-modes called long and short:

– Long addressing mode is more powerful be-

cause it can use the full 64 Kbyte address space,

however it uses more bytes and more CPU cy-

cles.

– Short addressing mode is less powerful because

it can generally only access page zero (0000h -

00FFh range), but the instruction size is more

compact, and faster. All memory to memory in-

structions use short addressing modes only

(CLR, CPL, NEG, BSET, BRES, BTJT, BTJF,

INC, DEC, RLC, RRC, SLL, SRL, SRA, SWAP)

The ST7 Assembler optimizes the use of long and

short addressing modes.

Table 19. ST7 Addressing Mode Overview

Mode

Syntax

Destination/

Source

Pointer Pointer

Address Size

(Hex.) (Hex.)

Length

(Bytes)

Inherent

nop

+0

Immediate

ld A,#$55

+1

Short

Direct

ld A,$10

00..FF

+1

Long

Direct

ld A,$1000

0000..FFFF

+2

No Offset Direct Indexed ld A,(X)

00..FF

+ 0 (with X register)

+ 1 (with Y register)

Short

Direct Indexed ld A,($10,X)

00..1FE

+1

Long

Direct Indexed ld A,($1000,X) 0000..FFFF

+2

Short

Indirect

ld A,[$10]

00..FF

00..FF byte

+2

Long

Indirect

ld A,[$10.w]

0000..FFFF

00..FF word + 2

Short

Indirect Indexed ld A,([$10],X) 00..1FE

00..FF byte

+2

Long

Relative

Relative

Indirect Indexed ld A,([$10.w],X) 0000..FFFF

00..FF word + 2

Direct

jrne loop

PC-128/PC+1271)

+1

Indirect

jrne [$10]

PC-128/PC+1271) 00..FF

byte

+2

Bit

Direct

bset $10,#7

00..FF

+1

Bit

Indirect

bset [$10],#7 00..FF

00..FF byte

+2

Bit

Direct Relative btjt $10,#7,skip 00..FF

+2

Bit

Indirect Relative btjt [$10],#7,skip 00..FF

00..FF byte

+3

Note 1. At the time the instruction is executed, the Program Counter (PC) points to the instruction follow-

ing JRxx.

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