Philips SAA7345 Status read operation sequence

1998 Feb 16 8

Philips Semiconductors Product speciﬁcation

CMOS digital decoding IC with RAM for

Compact Disc SAA7345

WRITING DATATO SAA7345; REPEAT MODE

The same command can be repeated several times (e.g. for fade function) by applying extra RAB pulses as shown in

Fig.6.

READING STATUSINFORMATION FROM SAA7345

There are several internal status signals which can be made available on the DA line (Table 1).

Table 1 Internal status signals.

The status signal to be output is selected by status control register (address 0010). The timing for reading the status

signal is shown in Fig.7.

Status read operation sequence

•Write appropriate data to register 0010 to select required status signal.

•With RAB LOW; set CL LOW.

•Set RAB HIGH; this will instruct the SAA7345 to output status signal on DA.

SIGNAL DESCRIPTION

SUBQREADY-I LOW if new subcode word is ready in Q-channel register.

MOTSTART1 HIGH if motor is turning at 75% or more of nominal speed.

MOTSTART2 HIGH if motor is turning at 50% or more of nominal speed.

MOTSTOP HIGH if motor is turning at 12% or less of nominal speed.

PLL Lock HIGH if Sync coincidence signals are found.

V1 Follows input on V1 pin.

V2 Follows input on V2 pin.

MOTOR-OV HIGH if the motor servo output stage saturates.

Note that CL must stay HIGH between RAB pulses.

Fig.6 Microcontroller WRITE timing; repeat mode.

A3 A2 A1 A0 D3 D2 D1 D0

DA (SAA7345)

MGA380 - 1

(microcontroller)

RAB

(microcontroller)

high impedance