ARM ARM7TDMI - Figure 4-6 Coprocessor Connections with Unidirectional Bus

Coprocessor Interface
ARM DDI 0210C Copyright © 2001, 2004 ARM Limited. All rights reserved. 4-13
Figure 4-6 Coprocessor connections with unidirectional bus
The logic for Figure 4-6 is as follows:
on FALLING MCLK
ASEL = ((nMREQ = 1 and SEQ = 1) and (not nRW))
CSEL = ((nMREQ = 1 and SEQ = 1) and (nRW))
4.5.2 Connecting multiple coprocessors
If you have multiple coprocessors in your system, connect the handshake signals as
follows:
nCPI Connect this signal to all coprocessors present in the system.
CPA and CPB
The individual CPA and CPB outputs from each coprocessor must be
ANDed together, and connected to the CPA and CPB inputs on the
ARM7TDMI processor.
You must multiplex the output data from the coprocessors.
Connecting multiple coprocessors is shown in Figure 4-7 on page 4-14.
ARM core
Memory
system
Coprocessor
CPDRIVE
ASEL
DIN
DOUT
CPDOUTCPDIN
CSEL
0
1
0
1
0
1