SAA7374GP PHILIPS [NXP Semiconductors], SAA7374GP Datasheet - Page 31

• Manufacturer Part Number: SAA7374GP
• Description: Low voltage digital servo processor and Compact Disc decoder CD7LV
• Manufacturer: PHILIPS [NXP Semiconductors]

Philips Semiconductors
If t
is below (2.6/n) ms, then t
microcontroller can read all subcode frames if it completes
the read operation within (2.6/n) ms after the subcode is
ready]. If this criterion is not met, it is only possible to
guarantee that t
(approximately).
If subcode frames with failed CRCs are present, the t
t
subcode frame.
It should be noted that in the lock-to-disc mode ‘n’ is
replaced by ‘d’, which is the disc speed factor.
7.15.1.6
A write data command is used to transfer data (a number
of bytes) from the microcontroller, using the protocol
shown in Fig.28. The first of these bytes is the command
byte and the following are data bytes; the number
(between 1 and 7) depends on the command byte.
It should be noted that RAB must be held LOW; the
command or data is interpreted by the SAA7374 after the
HIGH-to-LOW transition of SILD; there must be a
minimum time of 70 s between SILD pulses.
7.15.1.7
The same data byte can be repeated by applying extra
SILD pulses as shown in Fig.29. SCL must stay HIGH
between the SILD pulses
7.15.1.8
A read data command is used to transfer data (status
information) to the microcontroller, using the protocol
shown in Fig.30. The first byte written determines the type
of command. After this byte a variable number of bytes can
be read. It should be noted that RAB must be held LOW;
after the end of command byte (LOW-to-HIGH transition
on SILD) there must be a delay of 70 s before reading
data is started (i.e. on the next HIGH-to-LOW transition of
SILD); there must be a minimum time of 70 s between
SILD pulses.
1998 Feb 26
3
times will be increased by (13.1/n) ms for each defective
Low voltage digital servo processor and
Compact Disc decoder (CD7LV)
1
(SUBQREADY-I status LOW to end of subcode read)
Write servo commands
Writing repeated data in servo commands
Read servo commands
3
will be below (26.2/n) ms
2
= (13.1/n) ms [i.e. the
2
and
31
7.15.2
Bytes are transferred over the interface in groups (i.e.
servo commands) of which there are two types: write data
commands and read data commands.
The sequence for a write data command (that requires
3 data bytes) is as follows;
It should be noted that more than one command can be
sent in one write sequence.
The sequence for a read data command (that reads 2 data
bytes) is as follows:
It should be noted that the timing constraints specified for
the read and write servo commands must still be adhered
to.
Send START condition
Send address 30H (write)
Write command byte
Write data byte 1
Write data byte 2.
Write data byte 3
Send STOP condition.
Send START condition
Send address 30H (write)
Write command byte
Send STOP condition.
Send START condition
Send address 31H (read)
Read data byte 1
Read data byte 2
Send STOP condition.
M
ICROCONTROLLER INTERFACE
Product specification
(I
2
SAA7374
C-
BUS MODE
)