WM8804 datasheet(42/66 Pages) WOLFSON

42 / 66 page

WM8804

Production Data

PD Rev 4.1 September 2007

ERROR HANDLING IN SOFTWARE MODE

When the TRANS_ERR flag is asserted, it indicates that the recovered Rx S/PDIF sub-frame is

corrupted. This corruption can due to a BI-Phase error, a parity error or a pre-amble error. When the

INVALID flag is asserted, it indicates that the recovered Rx S/PDIF sub-frame has been marked as

being invalid by the source of the S/PDIF data. Both TRANS_ERR and INVALID indicate an error.

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

mechanism for each flag is similar. The mechanisms are described below.

MANUAL ERROR HANDLING

This manual handling of errored Rx S/PDIF data can be used when an application processor is being

interrupted via the INT_N signal. Appropriate action should be taken by the application processor to

handle the error condition

If the TRANS_ERR and INVALID error flags are not masked using the MASK register, the recovered

S/PDIF Rx data is passed to the digital audio interface or to the S/PDIF transmitter irrespective of the

state of the flag and the data content of the recovered stream.(Also refer to note below). In this case,

the application processor will be interrupted via the INT_N signal.

AUTOMATIC ERROR HANDLING

This automatic handling of errored Rx S/PDIF data can be used when an application processor is not

being interrupted via the INT_N signal leaving the WM8804 to handle the error condition.

If the TRANS_ERR and INVALID error flags are masked using the MASK register, the WM8804

output data from the S/PDIF Rx interface depends on the setting of FILLMODE. If FILLMODE=1,

then the incoming data (which is errored) is overwritten with 0’s. If FILLMODE=0, then the last valid

data sample is repeatedly output.

For the INVALID flag, the automatic error handling can be disabled if ALWAYSVALID =1. If

ALWAYSVALID is set, then the recovered Rx S/PDIF data, which is marked as invalid, will be

allowed to pass to the digital audio interface or to the S/PDIF transmitter. The data will not be

modified in any way.

Note:

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

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.

PLL6

08h

ALWAYSVALID

Automatic Error Handling Configuration for INVALID

Flag

0 = INVALID flag automatic error handling enabled.

1 = INVALID flag automatic error handling disabled.

Table 51 S/PDIF Receiver Automatic Error Handling Configuration Registers

WM8804 Datasheet(PDF) 42 Page - Wolfson Microelectronics plc

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