B.4. Coprocessor interface signals

Table B.3 describes the ARM946E-S coprocessor interface signals.

Table B.3. Coprocessor interface signals

Name

Direction

Description

CPCLKEN

Coprocessor clock enable

Output

Synchronous enable for coprocessor pipeline follower. When HIGH on the rising edge of CLK the pipeline follower logic can advance.

CPINSTR[31:0]

Coprocessor instruction data

Output

The 32-bit coprocessor instruction bus used to transfer instructions to the coprocessor pipeline follower.

CPDOUT[31:0]

Coprocessor read data

Output

The 32-bit coprocessor read data bus for transferring data to the coprocessor.

CPDIN[31:0]

Coprocessor write data

Input

The 32-bit coprocessor write data bus for transferring data from the coprocessor.

CPPASS

Output

Indicates that there is a coprocessor instruction in the Execute stage of the pipeline, that must be executed.

CPLATECANCEL

Output

If HIGH during the first memory cycle of a coprocessor instruction, then the coprocessor must cancel the instruction without changing any internal state. This signal is only asserted in cycles where the previous instruction causes a Data Abort to occur.

CHSDE[1:0]

Coprocessor handshake decode

Input

The handshake signals from the Decode stage of the coprocessor’s pipeline follower. Indicates ABSENT (10), WAIT (00), GO (01), or LAST (11).

CHSEX[1:0]

Coprocessor handshake execute

Input

The handshake signals from the Execute stage of the coprocessor’s pipeline follower. Indicates ABSENT (10), WAIT (00), GO (01), or LAST (11).

CPTBIT

Coprocessor instruction Thumb bit

Output

When HIGH indicates that the ARM946E-S is in Thumb state. When LOW indicates that the ARM946E-S is in ARM state. Sampled by the coprocessor pipeline follower.

nCPMREQ

Not coprocessor instruction request

Output

When LOW on the rising edge of CLK and CPCLKEN is HIGH, the instruction on CPINSTR must enter the coprocessor pipeline.

nCPTRANS

Not coprocessor memory translate

Output

When LOW indicates that the ARM946E-S is in User mode. When HIGH indicates that the ARM946E-S is in Privileged mode. Sampled by the coprocessor pipeline follower.

Copyright © 2000 ARM Limited. All rights reserved.ARM DDI 0155A
Non-Confidential