W88113C Datasheet, PDF (87/102 Pages) Winbond – ATAPI CD-ROM DECODER & CONTROLLER

W88113C
5.3 Host Interface
The host interface is a standard ATAPI interface with enhanced Ultra DMA support. The Ultra DMA
protocol could double the current burst transfer rate of 16.6MB/sec to 33MB/sec without hardware
changes such as termination devices or different cabling.
5.3.1 Ultra DMA Mode Setting
This decoder is capable of supporting Ultra DMA Mode 2. Device firmware could claim that Ultra
DMA mode 2 and below are supported in IDENTIFY DEVICE information.
Once Ultra DMA is enabled, the Ultra DMA burst is defined as the period from an assertion of
DMACKb to the subsequent negation of DMACKb. Three pins in the following table are re-defined
during an Ultra DMA burst.
Value of Register 1Fh PIO/DMA Ultra DMA Data-In x9h Ultra DMA Data-out xBh
pin 49
IORDY
DSTROBE
DDMARDYB
pin 50
HRDb
HDMARDYB
HSTROBE
pin 52
HWRb
STOP
STOP
The value of UDT1-0 (8Ah,5-4) defines the Ultra DMA Timing Factor, udtf, which control the timing
of Ultra DMA transfer.
Tcyc = ( 2 + udtf ) × Tudma
Where Tudma is clock period that depends on UCLKS (8Ah.3)
and Tcyc is Ultra DMA cycle time ( from DSTROBE edge to DSTROBE edge)
Device firmware should set udtf according to the clock source and the assigned Ultra DMA transfer
mode after host issues SET FEATURE command. If there are frequent CRC errors in data-in bursts,
device firmware may switch system to slower Ultra DMA mode by increasing udtf to improve data
integrity.
Example: If UCLKS (8Ah.w3) is low and system clock is 33.8688MHz, the udtf should be the
following value to abide by the determined Ultra DMA mode.
Ultra DMA
Tcyc Min. Spec.
Tcyc
udtf
Mode 0
114 ns
118 ns
2
Mode 1
75 ns
88.6 ns
1
Mode 2
55 ns
59 ns
0
5.3.2 Ultra DMA Data-out
The programming of Ultra DMA transfer is similar to that of Multi-word DMA transfer. One thing
should be noted is that device should prepare to receive one additional word at the end of a data out
burst. Since 12-byte Packet FIFOs are used to receive data in Ultra DMA data-out transfer, the value
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Publication Release Date: Mar. 1999
Revision 0.61