ST10R167 datasheet(12/63 Pages) STMICROELECTRONICS

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ST10R167

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V - CENTRAL PROCESSING UNIT (CPU)

The CPU includes a 4-stage instruction pipeline, a

16-bit arithmetic and logic unit (ALU) and dedi-

cated SFRs. Additional hardware has been added

for a separate multiply and divide unit, a bit-mask

generator and a barrel shifter.

Most of the ST10R167’s instructions can be exe-

cuted in one instruction cycle which requires 80ns

at 25MHz CPU clock. For example, shift and

rotate instructions are processed in one instruc-

tion cycle independent of the number of bits to be

shifted. Multiple-cycle instructions have been opti-

mized: branches are carried out in 2 cycles, 16 x

16 bit multiplication in 5 cycles and a 32/16 bit

division in 10 cycles.The jump cache reduces the

execution time of repeatedly performed jumps in a

loop, from 2 cycles to 1 cycle.

The

CPU

uses

actual

context

consisting of up to 16 Word wide GPRs physically

allocated within the on-chip RAM area. A Context

Pointer

(CP)

determines

the

base

address of the active register bank to be accessed

by the CPU. The number of register banks is only

restricted by the available internal RAM space.

For easy parameter passing, a register bank may

overlap others.

A system stack of up to 1024 Byte is provided as a

storage for temporary data. The system stack is

allocated in the on-chip RAM area, and it is

accessed by the CPU via the stack pointer (SP)

Two

separate

SFRs,

STKOV

and

STKUN, are implicitly compared against the stack

pointer value upon each stack access for the

detection of a stack overflow or underflow.

Figure 4 : CPU Block Diagram

Internal

RAM

2K Byte

General

Purpose

Registers

R15

MDH

MLD

Barrel-Shift

Mul./Div.-HW

Bit-Mask Gen.

ALU

16-Bit

STKOV

STKUN

Exec. Unit

Instr. Ptr

Instr. Reg

4-Stage

Pipeline

PSW

SYSCON

BUSCON 0

BUSCON 1

BUSCON 2

BUSCON 3

BUSCON 4

ADDRSEL 1

ADDRSEL 2

ADDRSEL 3

ADDRSEL 4

Data Pg. Ptrs

Code Seg. Ptr.

CPU

External

Memory

Bank

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