ST72254G1M5 View Datasheet(PDF) - STMicroelectronics

Part Name

Description

Manufacturer

ST72254G1M5

8-BIT MCU WITH SINGLE VOLTAGE FLASH MEMORY, ADC, 16-BIT TIMERS, SPI, I2C INTERFACES

STMicroelectronics 

ST72104G, ST72215G, ST72216G, ST72254G

13.2 INSTRUCTION GROUPS

The ST7 family devices use an Instruction Set

consisting of 63 instructions. The instructions may

be subdivided into 13 main groups as illustrated in

the following table:

Load and Transfer

Stack operation

Increment/Decrement

Compare and Tests

Logical operations

Bit Operation

Conditional Bit Test and Branch

Arithmetic operations

Shift and Rotates

Unconditional Jump or Call

Conditional Branch

Interruption management

Code Condition Flag modification

LD

PUSH

INC

CP

AND

BSET

BTJT

ADC

SLL

JRA

JRxx

TRAP

SIM

CLR

POP

DEC

TNZ

OR

BRES

BTJF

ADD

SRL

JRT

WFI

RIM

RSP

BCP

XOR

SUB

SRA

JRF

HALT

SCF

CPL NEG

SBC

RLC

JP

MUL

RRC

CALL

SWAP

CALLR

IRET

RCF

SLA

NOP RET

Using a pre-byte

The instructions are described with one to four

bytes.

In order to extend the number of available op-

codes for an 8-bit CPU (256 opcodes), three differ-

ent prebyte opcodes are defined. These prebytes

modify the meaning of the instruction they pre-

cede.

The whole instruction becomes:

PC-2 End of previous instruction

PC-1 Prebyte

PC Opcode

PC+1 Additional word (0 to 2) according to the

number of bytes required to compute the

effective address

These prebytes enable instruction in Y as well as

indirect addressing modes to be implemented.

They precede the opcode of the instruction in X or

the instruction using direct addressing mode. The

prebytes are:

PDY 90 Replace an X based instruction using

immediate, direct, indexed, or inherent

addressing mode by a Y one.

PIX 92

Replace an instruction using direct, di-

rect bit, or direct relative addressing

mode to an instruction using the corre-

sponding indirect addressing mode.

It also changes an instruction using X

indexed addressing mode to an instruc-

tion using indirect X indexed addressing

mode.

PIY 91 Replace an instruction using X indirect

indexed addressing mode by a Y one.

93/140

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