C164SL datasheet(59/484 Pages) INFINEON

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C164CI/C164SI

Derivatives

Central Processing Unit (CPU)

User’s Manual

4-1

V3.1, 2002-02

Central Processing Unit (CPU)

Basic tasks of the Central Processing Unit (CPU) are to fetch and decode instructions,

to supply operands for the Arithmetic and Logic unit (ALU), to perform operations on

these operands in the ALU, and to store the previously calculated results. As the CPU is

the main engine of the C164CI microcontroller, it is also affected by certain actions of the

peripheral subsystem.

Because a four stage pipeline is implemented in the C164CI, up to four instructions can

be processed in parallel. Most instructions of the C164CI are executed in one machine

cycle (2 CPU clock periods) due to this parallelism.

This chapter describes how the pipeline works for sequential and branch instructions in

general, and the hardware provisions which have been made to speed up execution of

jump instructions in particular. General instruction timing is described including standard

and exceptional timing.

While internal memory accesses are normally performed by the CPU itself, external

peripheral or memory accesses are performed by a particular on-chip External Bus

Controller (EBC) which is invoked automatically by the CPU whenever a code or data

address refers to the external address space.

Figure 4-1

CPU Block Diagram

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