PC87570 datasheet(131/168 Pages) NSC

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Development System Support

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18.4.3

Pipe Status Signals

The Pipe Flow Signal (PFS) indicates the completion of an

instruction in the CR16A. The Pipe Long Instruction (PLI)

signal indicates the size of the completed instruction, where

0 = word instruction and 1 = double-word instruction. If an

instruction flashes the pipeline, the fetch for the next instruc-

tion (BST=101) is issued during the cycle following the in-

struction’s PFS, or later. See Figure 18-1.

18.5 DEVELOPMENT SYSTEM REGISTERS

18.5.1

Debug Configuration Register (DBGCFG)

The DBGCFG Register is a byte-wide, read/write register

that controls the configuration of debug support features.

Upon reset, DBGCFG is cleared (0).

The DBGCFG Register controls the debug features. Only

the development tools may access DBGCFG. This enables

application software to be binary compatible in all environ-

ments.

Bit 0 - ON

0: In IRE and IRD environments, always cleared to 0;

any data written to it is ignored.

1: In Dev environment, enables the following debug

support features:

- ISE interrupt input signal

- Use of other bits in the DBGCFG.

Bit 1 - FREEZE

0: No effect

1: When ON is 1, stops the WATCHDOG timer from

counting. All destructive reads (i.e., bits set or

cleared by read operations and other events trig-

gered by reads), become indifferent to reads. An

exception is the NMISTAT Register, which is not ef-

fected by reads. Additional modules may be frozen

as deﬁned by DBGFRZEN Register. FREEZE has

no effect when ON is 0.

18.5.2

Debug Freeze Enable Register (DBGFRZEN)

The DBGFRZEN Register is a byte-wide, read/write register

that enables the freeze operation on some modules during

debug. Each bit when set, enable the freeze of activities in

the respective module when the DBGCFG.FREEZE bit is set

(if DBGCFG.ON=1). Upon reset, DBGFRZEN is cleared (0).

Bit 0 - MFT16 Freeze Enable (MFT16FEN)

0: FREEZE in the DBGCFG Register has no effect on

the MFT16

1: Freezes the MFT16 when FREEZE is set

Bit 1 - ACB Freeze Enable (ACBFEN)

0: FREEZE in the DBGCFG Register has no effect on

the ACB interface

1: Freezes the ACB interface when FREEZE is set

Reserved

FREEZE

CLK

PFS

PLI

Instruction i

Completed

Instruction i+1

Completed

Figure 18-1. Pipe Status Signal (PFS and PLI)

Reserved

ACBFEN

MFT16FEN

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