LSI Logic Confidential
Async Slave WRITE and READ Protocols
8-5
Copyright © 2001, 2002 by LSI Logic Corporation. All rights reserved.
8.2.2
Transfer Mode B
For Mode B, the Host interface is configured for 16-bit I/O transfers and
16-bit DMA transfers. This transfer mode uses the Host interface
read/write protocols called I-mode and M-mode.
summarizes the transfer modes and port availability.
8.3
Async Slave WRITE and READ Protocols
The Host interface supports either separate RD and WR strobes
(I-mode) or a single CS strobe with a single WR signal (M-mode).
8.3.1
I-Mode WRITE and READ Operations
To select I-mode, the Host should perform a dummy read cycle to the
Host Address Register (address 0x4) using the RD strobe in the first
Host access after reset.
In I-mode, the address is sampled when WAIT and DTACK are driven
once WR or RD go LOW.
8.3.2
I-Mode Incoming Transfers
shows an I-mode write. The sequence is as follows:
•
The Host drives the address and CS (1), and asserts WR (2) after
the address and chip select are stable.
•
The DMN-8600 processor asserts both WAIT and DTACK from a
3-state level to a high level (shaded area is 3-state) (3) in response
to the assertion of WR.
•
The DMN-8600 processor deasserts WAIT (4) and then asserts
DTACK (4) when it is ready to take data in.
Table 8.1
Transfer Modes and Port Configurations
Mode
Port Transfer Description
A
32-bit and DMA 32-bit I/O
B
16-bit and DMA 16-bit I/O