ARM ARM926EJ-S User Manual

Coprocessor Interface
8-14 Copyright © 2001-2003 ARM Limited. All rights reserved. ARM DDI0198D
8.10 Connecting multiple external coprocessors
If multiple coprocessors are connected to the ARM926EJ-S processor, then outputs of
the various coprocessors must be combined to form a single set of coprocessor inputs.
The coprocessor handshake signals are combined together by ANDing the top bit and
ORing the bottom bit. This enables a coprocessor to produce a fixed response of
b10
(Absent), when it is inactive. The other external coprocessor inputs, CPDIN and
CPBURST, are combined by ORing. This is shown in Figure 8-10.
Figure 8-10 Arrangement for connecting two coprocessors
The OR arrangement for CPBURST and CPDIN means that coprocessors must drive
zero values onto their CPBURST and CPDIN outputs when they are inactive, or do not
own the corresponding coprocessor pipeline stage associated with these signals.
CHSDEa[1]
CHSDEb[1]
CHSDEa[0]
CHSDEb[0]
CHSEXa[1]
CHSEXb[1]
CHSEXa[0]
CHSEXb[0]
CPBURSTa[3:0]
CPBURSTb[3:0]
CPDINa[3:0]
CPDINb[3:0]
CHSDE[1]
CHSDE[0]
CHSDE[1:0]
ARM926EJ-S
CHSEX[1]
CHSEX[0]
CHSEX[1:0]
CPBURST[3:0]
CPDIN[3:0]

ARM ARM926EJ-S Specifications

General

Brand	ARM
Model	ARM926EJ-S
Category	Computer Hardware
Language	English