ST7FLITE25(2003) 데이터 시트보기 (PDF) - STMicroelectronics

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ST7FLITE25
(Rev.:2003)

8-BIT MCU WITH SINGLE VOLTAGE FLASH MEMORY, DATA EEPROM, ADC, TIMERS, SPI

STMicroelectronics 

ST7LITE2

6 CENTRAL PROCESSING UNIT

6.1 INTRODUCTION

This CPU has a full 8-bit architecture and contains

six internal registers allowing efficient 8-bit data

manipulation.

6.2 MAIN FEATURES

s 63 basic instructions

s Fast 8-bit by 8-bit multiply

s 17 main addressing modes

s Two 8-bit index registers

s 16-bit stack pointer

s Low power modes

s Maskable hardware interrupts

s Non-maskable software interrupt

6.3 CPU REGISTERS

The 6 CPU registers shown in Figure 10 are not

present in the memory mapping and are accessed

by specific instructions.

Figure 10. CPU Registers

7

0

RESET VALUE = XXh

7

0

RESET VALUE = XXh

7

0

RESET VALUE = XXh

15

PCH

87

PCL

0

RESET VALUE = RESET VECTOR @ FFFEh-FFFFh

7

0

1 1 1 HI NZ C

RESET VALUE = 1 1 1 X 1 X X X

15

87

0

RESET VALUE = STACK HIGHER ADDRESS

Accumulator (A)

The Accumulator is an 8-bit general purpose reg-

ister used to hold operands and the results of the

arithmetic and logic calculations and to manipulate

data.

Index Registers (X and Y)

In indexed addressing modes, these 8-bit registers

are used to create either effective addresses or

temporary storage areas for data manipulation.

(The Cross-Assembler generates a precede in-

struction (PRE) to indicate that the following in-

struction refers to the Y register.)

The Y register is not affected by the interrupt auto-

matic procedures (not pushed to and popped from

the stack).

Program Counter (PC)

The program counter is a 16-bit register containing

the address of the next instruction to be executed

by the CPU. It is made of two 8-bit registers PCL

(Program Counter Low which is the LSB) and PCH

(Program Counter High which is the MSB).

ACCUMULATOR

X INDEX REGISTER

Y INDEX REGISTER

PROGRAM COUNTER

CONDITION CODE REGISTER

STACK POINTER

X = Undefined Value

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