SAA7380 Datasheet, PDF (13/60 Pages) NXP Semiconductors – Error correction and host interface IC for CD-ROM ELM

Philips Semiconductors
Error correction and host interface IC for
CD-ROM (ELM)
Preliminary specification
SAA7380
7.7 Register Descriptions
7.7.1 SBOUT/ADATA
This is a 12 byte FIFO used to transfer data from the
sub-CPU to the host.
In the Sanyo and Oak compatibility mode writing to this
register starts a status byte transfer. In this mode if the
SOUTEN bit in the IFCTRL register has been set to logic 1,
writing to the SBOUT register sets the STBSY bit to
logic 0. If the STWAI bit is set to logic 0, STEN is
immediately set LOW to inform the host computer that the
status byte is ready to be read from.
If the STWAI bit is set to logic 1 and the DTEN bit in the
IFSTAT register is also set to logic 1, both the STEN pin
and the STBSY will go LOW. However, if the STWAI bit is
set to logic 0, and the DTEN bit is set to logic 0, then STEN
is held HIGH until the DTEN bit goes HIGH, thereafter it
goes LOW.
7.7.2 COMIN/ APCMD
During the ATAPI mode this register is used to read the
program command sent by the host. The program
command can only be received if the appropriate mode
has been selected (see Table 22) and a data transfer has
been started (see DTRG register).
During Sanyo and Oak compatibility modes this register is
a 12 byte FIFO which is used to transfer commands from
the host to the sub-CPU. If reading this register empties
the command FIFO then CMDI is set to logic 1 and further
reads from the register will return FFH.
7.7.3 IFCTRL
The IFCTRL register provides control over the host
interface. Resetting the chip will clear all bits. In the ATAPI
mode, only, bits 7 to 5 have any effect.
Table 3 IFCTRL register bits
BIT
NAME
DESCRIPTION
7
CMDIEN Enable bits for CMDI, DTEI and DECI. These are interrupt masks, enabling/disabling the
6
DTEIEN ^{sub-CPU interrupt pin. They do not affect the bits in the IFSTAT register. If set to logic 1,}
5
DECIEN
the corresponding interrupt is enabled. It should be noted that these masks do not clear
the interrupts.
4
CMDBK Command break enable. If set to logic 0 then the command break function is enabled
and if the host writes to the COMIN FIFO then any data or status byte transfers in
progress will be terminated. If set to logic 1 then this operation is disabled. The data
transfer interrupt DTEI is not generated by a command break.
3
DTWAI Data transfer WAIT enable. Setting this bit to logic 0 enables the data WAIT function.
The data WAIT function allows the SAA7380 to delay hardware execution of the data
transfer until a status byte transfer has been completed. Disabling the data WAIT
function allows data transfers to take place independently of status byte transfers.
2
STWAI Status byte transfer WAIT enable. This bit acts in a similar way to the DTWAI bit except it
controls the status WAIT function. The status WAIT function allows the SAA7380 to
delay hardware execution of the status transfer until a data byte transfer has been
completed. Disabling the data WAIT function allows status transfers to take place
independently of data transfers.
1
DOUTEN Data output enable. DOUTEN enables/disables data transfers. When set to logic 0, all
data transfers in progress are aborted.
0
SOUTEN Status output enable. SOUTEN enables/disables status byte transfers. When set to
logic 0, the status FIFO register is reset to empty and all status byte transfers in progress
are aborted.
1996 Apr 25
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