ST7FLITE20(2003) Просмотр технического описания (PDF) - STMicroelectronics
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производитель
ST7FLITE20
(Rev.:2003)
(Rev.:2003)
STMicroelectronics
ST7FLITE20 Datasheet PDF : 131 Pages
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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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