saa7327 NXP Semiconductors, saa7327 Datasheet - Page 34

• Manufacturer Part Number: saa7327
• Description: Digital Servo Processor And Compact Disc Decoder With Integrated Dac For Video Cd Cd7 Ii
• Manufacturer: NXP Semiconductors

Philips Semiconductors
It should be noted that RAB must be held LOW;
the command or data is interpreted by the SAA7327 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 illustrated in Fig.30. SCL must be 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.31. 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 the command byte (LOW-to-HIGH
transition on SILD) there must be a delay of 70 s before
reading data is started (i.e. the next HIGH-to-LOW
transition on SILD); there must be a minimum time of 70 s
between SILD pulses.
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:
2000 Jun 26
Digital servo processor and Compact Disc
decoder with integrated DAC for video CD (CD7 II)
M
Writing repeated data in servo commands
Read servo commands
ICROCONTROLLER INTERFACE
(microcontroller)
(microcontroller)
(microcontroller)
(SAA7327)
SDA
SCL
SDA
RAB
Fig.23 Microcontroller write protocol for registers 0 to F.
A3
(I
2
C-
BUS MODE
A2
A1
)
high-impedance
A0
34
D3
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.
D2
D1
D0
Product specification
MGS236
SAA7327