LSI Logic Confidential
ATAPI Interface
14-3
Copyright © 2001, 2002 by LSI Logic Corporation. All rights reserved.
Figure 14.1 ATAPI Read and Write Cycle
The wait cycle can be generated by the ATAPI device driving the
ATAPI_IORDY signal low during the read cycle. The ATAPI device must
drive the ATAPI_IORDY signal low before time tA to initiate a wait cycle.
During the wait cycle, the ATAPI Interface keeps the register address and
the ATAPI_DIOR signal asserted until the ATAPI_IORDY signal becomes
high.
14.1.2 Write Cycle
The ATAPI write cycle starts when the ATAPI Interface receives the
ATAPI_WR command from the host. The ATAPI Interface follows by
placing the register address on the address bus and asserting the
ATAPI_DIOW signal time t1 later.
The ATAPI device can also initiate the wait cycle by driving the
ATAPI_IORDY signal low before time tA. During the wait cycle, the ATAPI
Interface keeps the register address, write the data, and the
ATAPI_DIOW signal asserted until the ATAPI_IORDY signal becomes
high.
14.1.3 DMA Operation
The DMA operation is used for transferring long sets of data to or from
the ATAPI device. The host must do several ATAPI register read/writes to
the ATAPI device using the ATAPI_RD and ATAPI_WR commands before
it can initiate the ATAPI DMA transfer from the host.
ATAPI_DIOR/DIOW (O)
ATAPI_ADDR[4:0] (O)
ATAPI_DATA[15:0]
ATAPI_DATA[15:0]
ATAPI_IORDY (I)
t
1
Address Valid
t
A
(CS0, CS1, DA2, DA1, DA0)
(Write) (I/O)
(Read) (I/O)