CS493302-IL View Datasheet(PDF) - Cirrus Logic

Part Name

Description

MFG CO.

CS493302-IL

Multi-Standard Audio Decoder Family

Cirrus Logic 

INTREQ = 0

YES

READ_BYTE_*(HOST CONTROL REGISTER)

NO

HOUTRDY==1

YES

READ_BYTE_*(HOST MESSAGE REGISTER)

YES

MORE BYTES

TO READ?

NO

WAIT 100 uS

READ_BYTE_*(HOST CONTROL REGISTER)

HOUTRDY==1

YES

NO

FINISHED

Figure 29. Typical Parallel Host Mode Control

Read Sequence Flow Diagram

CS49300 Family DSP

the communication interface. Please note that

‘Read_Byte_*()’ is a generalized reference to

either Read_Byte_MOT() or Read_Byte_INT().

3) In order to determine whether the CS493XX

has an outgoing control byte that is valid, the

host must check the HOUTRDY bit of the Host

Control Register (bit 1). If HOUTRDY is high,

then the Host Message Register contains a

valid message byte for the host. If HOUTRDY

is low, then the DSP has not placed a new

control byte in the Host Message Register, and

the host should poll the Host Control Register

again.

4) The host knows that the DSP is ready to

provide a new response byte at this point. The

host can safely read a byte from the Host

Message Register (A[1:0] = 00b).

5) If the host expects to read any more response

bytes, the host should once again check the

HOUTRDY bit (return to step 1). Please refer to

one of the application code user’s guides to

determine the length of messages to read from

the CS493XX. Typically this length is 1, 3 or 6

bytes, and can be deduced from the message

OPCODE.

6) After the response has been read the host

should wait at least 100 uS and check

HOUTRDY one final time. If HOUTRDY is high

once again this means that an unsolicited

message has come during the read process

and the host has another message to read (i.e.

skip back to step 4 and read out the new

message).

50

DS339F7

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