SAA7385 Datasheet, PDF (51/64 Pages) NXP Semiconductors – Error correction and host interface IC for CD-ROM SEQUOIA

Philips Semiconductors
Error correction and host interface IC for
CD-ROM (SEQUOIA)
Preliminary specification
SAA7385
15.5 S2B interface timing
The S2B serial interface consists of four lines (see Fig.17):
Transmit data (TXD)
Receive data (RXD)
Data path ready to accept data; active LOW (CPR)
Basic engine ready to accept data; active LOW (SPR).
These are used for communication. TXD and CPR for
sending acknowledges and information data to the data
path and RXD and SPR for receiving commands and
parameters from the data path. The data is transferred
frame-wise and asynchronously.
A data frame is proceeded by a start-bit (active LOW),
followed by the actual data byte, and again followed by a
parity bit (even parity), and a stop bit (active HIGH),
see Fig.18. In total, eleven bits per frame are incorporated.
The interface is full duplex, meaning data frames may be
transmitted and received simultaneously.
The bit-rate is selectable:
187.5 kbits/s with a 2.6% error
62.5 kbits/s with a 0.4% error
31.25 kbits/s with a 0.4% error.
handbook, halfpage^{data path}
RXD
CPR
TXD
SPR
sequoia
basic engine
TXD
CPR
RXD
SPR
MGE403
Fig.17 S2B interface.
1996 Jun 19
handb_To_Xo_Dk, halfpage _{S0 0 1 2 3 4 5 6 7 P S1}
CPR
MGE404
Fig.18 S2B Timing.
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