WM8581 datasheet(70/100 Pages) WOLFSON

70 / 100 page

WM8581

Production Data

PD Rev 4.0 April 2007

ERROR HANDLING IN SOFTWARE MODE

When the TRANS_ERR flag is asserted, the recovered S/PDIF sub-frame is corrupted. When the

INVALID flag is asserted, the recovered S/PDIF sub-frame is marked as being invalid.

The S/PDIF receiver has two modes of error handling for these errors, manual and automatic. The

mechanism for each flag is similar and is described below.

MANUAL ERROR HANDLING

When the flag is not masked using the MASK register, the recovered S/PDIF data is passed to the

digital audio interface and DAC1 or to the S/PDIF transmitter (note 1) irrespective of the state of the

flag and the data content of the recovered stream. In this case the application processor will be

interrupted via the INT_N signal and appropriate action should be taken by the application processor

to handle the error condition.

AUTOMATIC ERROR HANDLING

When the flag is masked using the MASK register, the WM8581 will automatically overwrite the

recovered S/PDIF data with either all-zeros or the last valid data sample depending on the status of

FILLMODE. In this case the application processor will not be interrupted via the INT_N signal and

appropriate action will be taken by the WM8581 to handle the error condition.

The automatic error handling can be disabled for the INVALID flag if the ‘ALWAYSVALID’ bit is set. In

this case, recovered data which is marked as invalid will be allowed to pass to the digital audio

interface or to the S/PDIF transmitter.

Notes

For the S/PDIF receiver to S/PDIF transmitter data path, only the INVALID flag will cause data to

be overwritten, the TRANS_ERR flag is not used to overwrite data which is passed to the

S/PDIF transmitter.

ADDRESS

BIT

LABEL

DEFAULT

DESCRIPTION

R38

GP01

26h

FILLMODE

Fill Mode Overwrite Configuration

Determines S/PDIF receiver action when TRANS_ERR or

INVALID flag is masked and error condition sets the flag:

0 = Data from S/PDIF receiver is overwritten with last valid

data sample when flag is set.

1 = Data from S/PDIF receiver is overwritten as all zeros

when flag is set.

R39

GP02

27h

ALWAYSVALID

Automatic Error Handling Configuration for INVALID

Flag

0 = INVALID flag automatic error handling enabled.

1 = INVALID flag automatic error handling disabled.

Table 65 S/PDIF Receiver Automatic Error Handling Configuration Registers

NON-AUDIO DETECTION

Non-Audio data is indicated by the AUDIO_N and PCM_N flags. AUDIO_N is recovered from the

Channel Status block. PCM_N is set on detection of the 96-bit IEC-61937 non-audio data sync code,

embedded in the data section of the S/PDIF frame. If DAC1 is sourcing the S/PDIF Receiver and

either the AUDIO_N or PCM_N flags are asserted, DAC1 is automatically muted using the softmute

feature. As described above, any change of AUDIO_N or PCM_N status will cause an INT_N

interrupt (UPD_NON_AUDIO) to be generated. If the MASK register bit for AUDIO_N or PCM_N is

set, then the associated signal will not generate an interrupt (UPD_NON_AUDIO) but the DAC will be

muted.

WM8581 Datasheet(PDF) 70 Page - Wolfson Microelectronics plc

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